75mm f/1.8 on the E-M5

Started Apr 11, 2012 | Discussions
odl
odl
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Re: No magic -- simple physics.
In reply to Great Bustard, Apr 12, 2012

Great Bustard wrote:

odl wrote:

Depends on the FF camera, my a850 wouldnt look the same, the high ISO of the camera wouldnt keep up.

If the A850's sensor is anything like the A900's:

http://www.sensorgen.info/SonyA900.html

then it is very inefficient -- low QE and relatively high read noise at high ISOs (but low read noise at low ISOs).

Well, I bought it for the studio

Again, that isnt always the case is it? If I buy the OMD it appears my a850 would not perform on par for the equivalence argument. That is why Great Bustard ensures he adds the equivalent sensor efficiency point.

Indeed. GB is careful to spell out the conditions, 'cause often when he doesn't, he gets called on it (but often when he does, someone accuses him of too much "technobabble").

Damned if you do, damned if you dont... it is a wonder why you bother

Equivalence tells what kind of images can be done and which cannot be done with a given set of equipment.

No, the photographer knows what he can and cannot do with the camera he has in his hands. Equivalance only works for those who have shot with 35mm film or FF. Anyone who hasnt it means nothing.

Equivalence is only relevant when comparing different formats:

josephjamesphotography.com/equivalence/#quick

  • Equivalence is only relevant when comparing different formats. For example, if we are comparing the performance of a 50mm lens designed for 135 (35mm FF) to a 50mm lens designed for APS-C or 4/3, both lenses being used on the same camera, Equivalence does not come into play.

In other words, had no one been comparing the 75 / 1.8 on mFT to the 135 / 2L on FF, then there'd have been no need to speak of Equivalence.

I think they comparison when that lens was brought up was a very nice one, and was not to do with the type of equivalence it quickly descended into...

Ab

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MAubrey
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Re: Either way, a must-buy
In reply to Yohan Pamudji, Apr 12, 2012

Yohan Pamudji wrote:

odl wrote:

One reason why a 75mm f.18 for m43rds could be more expensive is it isnt a traditional focus mechanism, or focus element... Look at what a samyang 85mm f1.4 costs... That gives some idea as to a cost difference between an AF lens and a non-AF lens...

Interesting, but I've never heard this argument before. Do you know for sure that a CDAF-compatible AF mechanism is more costly than a PDAF one?

The Samyang isn't PDAF. It's manual focus all the way. He's saying AF is more expensive the MF.
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odl
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Re: Either way, a must-buy
In reply to Yohan Pamudji, Apr 12, 2012

Yohan Pamudji wrote:

odl wrote:

One reason for pricing difference is expected sales vs R&D, Tooling, production, marketing etc. etc.

Understood. Still not worth more than 2x over the equivalent FF lens.

Well, as I dont have absolute numbers I am only talking loosely. It will be more expensive, as to how much more... well some also comes down to release date, demand etc.

One reason why a 75mm f.18 for m43rds could be more expensive is it isnt a traditional focus mechanism, or focus element... Look at what a samyang 85mm f1.4 costs... That gives some idea as to a cost difference between an AF lens and a non-AF lens...

Interesting, but I've never heard this argument before. Do you know for sure that a CDAF-compatible AF mechanism is more costly than a PDAF one?

I would imagine that looking at the performance of the samyang, there is something afoot (it is a solid lens). The purpose of MSC is to be quick, quiet, small and therefore needs to be designed with AF elements that can respond... So just as a internal focussing lens costs more than an external one, these are more limitation and pressures on the design. I also use the word "could". But I could ask you the same, do you know that it shouldnt cost 2x more?

Then there is the quality aspect. To perform as well as an 85mm f1.8 on a FF 18mp body, the m43rds lens must be sharper and with fewer aberrations, or it will look soft, high CA distortion etc, as they are all magnified.

I don't think so. The m4/3 sensor crops the middle 1/4 of the imaging circle area, i.e. the sharpest area. Developing a 75mm f/1.8 to cover a m4/3 sensor isn't more challenging than an 85mm f/1.8 to cover a FF sensor, especially with the aid of software correction on the m4/3, which you know will put to good use.

No, I am talking about the quality of the glass. All we have to do it put my sony 50mm on my a850, then on my m43rds, the perfomace, sharpness, contrast etc all drop on m43rds but I get more reach. It is the demands ont he optics for the density of the sensor that I am talking about.

All of these play a part, then that "cool aid" as you put it is real. While you may not want FF f1.8 DoF you do want the faster shutter speed, or the lower ISO. YOu also want the compression that 300mm brings to images, or the effective reach.

What does this have to do with the cost of the lens? Effective reach should never factor into the cost of the lens because it's dependent on sensor size and pixel density. As I rhetorically asked before, should the same lens cost more on a Nikon J1 or a Pentax Q because it has more effective reach?

You are saying that people are fooling themselves, But effective reach is important as long as there is no reduction in quality. Just look at some lens tests from apsc to ff bodies and see the varying performances. When I bring up this point I am only talking about the excitement over the lens, not the cost.

It isnt cool aid, and it is a new format. I paid a bit less than twice as much for my PL25mm f1.4 than I did for my SOny 50mm f1.4. But the sony is soft in the corners wide open, and full of IQ issues outside the center... The PL doesnt do that to nearly the same degree...

There's something to be said for that. But then again assuming equivalent tech of m4/3 vs. FF you could shoot the 50mm at f/2.8 and turn up the ISO 2 stops and compare the image quality at those settings. I don't know about the Sony specifically, but I bet most 50mm f/1.4 lenses would look better stopped down to f/2.8 than the PL25mm does wide open, but that's just my guess.

I could, but sometimes you dont have the ISO room to just stop down, sometimes you dont have the shutterspeed room either, and as GB and I have been duscussing the a850 is not known for its high ISO, so I would be gaining on one end and losing on the other.

The benefits are real, not imagines. The lens pricing is high, but fair for the product design and market. Want to shoot cheap at 75mm get the 40-150 or another comparable zoom.

I have the cheap 40-150mm. It's a great value. I don't expect the 75mm f/1.8 to be that cheap, just for it to be reasonably closer to what the actual materials cost instead of what its FF equivalent focal length is. I could live with $600-$700 keeping in mind economy of scale, R&D costs, etc., but I fear it will be closer to $1000. I'm still going with my $999 guess and just hope to be very much on the high end of wrong.

I hope it will go for around $700 I agree $1000 is quite steep, but I dont jump to the conclusion that it is price gouging. If it doesnt sell we will see price drops, if it does we wont (or there is no room for major discounting) But time will tell

Ab

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MAubrey
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Re: No magic -- simple physics.
In reply to Great Bustard, Apr 12, 2012

Well, at the very least, there is a sweet spot for equivalence around 50mm for μ43, where its physically possible (and reasonable) to have a f/1 lens (or f/1.1 in Voigtlander's case) which is then equivalent is DOF and AOV to a 100mm f/2 on a FF camera.

Had the 75mm been f/1.4 we could perhaps say the same, since 150 f/2.8 is also viewed as rather fast for such an angle of view.
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bgalb
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Re: 75mm f/1.8 on the E-M5
In reply to Gakuranman, Apr 12, 2012

This is a really nice looking lens, but I have a hard time picturing what I would use it for. The 45mm f1.8 . Yes, I could use one. But would much rather have a fast mid-range zoom than a 75mm prime.

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Yohan Pamudji
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Re: Either way, a must-buy
In reply to odl, Apr 12, 2012

odl wrote:

One reason why a 75mm f.18 for m43rds could be more expensive is it isnt a traditional focus mechanism, or focus element... Look at what a samyang 85mm f1.4 costs... That gives some idea as to a cost difference between an AF lens and a non-AF lens...

Interesting, but I've never heard this argument before. Do you know for sure that a CDAF-compatible AF mechanism is more costly than a PDAF one?

I would imagine that looking at the performance of the samyang, there is something afoot (it is a solid lens). The purpose of MSC is to be quick, quiet, small and therefore needs to be designed with AF elements that can respond... So just as a internal focussing lens costs more than an external one, these are more limitation and pressures on the design. I also use the word "could". But I could ask you the same, do you know that it shouldnt cost 2x more?

No, I don't. But I reckon it's conventional wisdom. If you're going to propose something that defies conventional wisdom I think the burden of proof is on you

Then there is the quality aspect. To perform as well as an 85mm f1.8 on a FF 18mp body, the m43rds lens must be sharper and with fewer aberrations, or it will look soft, high CA distortion etc, as they are all magnified.

I don't think so. The m4/3 sensor crops the middle 1/4 of the imaging circle area, i.e. the sharpest area. Developing a 75mm f/1.8 to cover a m4/3 sensor isn't more challenging than an 85mm f/1.8 to cover a FF sensor, especially with the aid of software correction on the m4/3, which you know will put to good use.

No, I am talking about the quality of the glass. All we have to do it put my sony 50mm on my a850, then on my m43rds, the perfomace, sharpness, contrast etc all drop on m43rds but I get more reach. It is the demands ont he optics for the density of the sensor that I am talking about.

Honestly I don't know how much this really plays into things. For years now we've been hearing that sensors will soon out-resolve lenses, but for good-to-great FF glass that's still not true (Nikon D800 might start making that a reality though). I'm willing to accept that designing good glass to out-resolve the smaller pixels of m4/3 can be more challenging.

It isnt cool aid, and it is a new format. I paid a bit less than twice as much for my PL25mm f1.4 than I did for my SOny 50mm f1.4. But the sony is soft in the corners wide open, and full of IQ issues outside the center... The PL doesnt do that to nearly the same degree...

There's something to be said for that. But then again assuming equivalent tech of m4/3 vs. FF you could shoot the 50mm at f/2.8 and turn up the ISO 2 stops and compare the image quality at those settings. I don't know about the Sony specifically, but I bet most 50mm f/1.4 lenses would look better stopped down to f/2.8 than the PL25mm does wide open, but that's just my guess.

I could, but sometimes you dont have the ISO room to just stop down, sometimes you dont have the shutterspeed room either, and as GB and I have been duscussing the a850 is not known for its high ISO, so I would be gaining on one end and losing on the other.

That's why I mentioned equivalent tech. The E-M5 is looking close to equal my old Canon 5D in high ISO performance, which throws off the equivalence calculations in favor of the E-M5 the same way it does vs. your a850. Anyway, I'm not a fan of comparing focal view equivalence when comparing lens prices. That was my whole beef with m4/3 lens pricing in the first place.

The benefits are real, not imagines. The lens pricing is high, but fair for the product design and market. Want to shoot cheap at 75mm get the 40-150 or another comparable zoom.

I have the cheap 40-150mm. It's a great value. I don't expect the 75mm f/1.8 to be that cheap, just for it to be reasonably closer to what the actual materials cost instead of what its FF equivalent focal length is. I could live with $600-$700 keeping in mind economy of scale, R&D costs, etc., but I fear it will be closer to $1000. I'm still going with my $999 guess and just hope to be very much on the high end of wrong.

I hope it will go for around $700 I agree $1000 is quite steep, but I dont jump to the conclusion that it is price gouging. If it doesnt sell we will see price drops, if it does we wont (or there is no room for major discounting) But time will tell

Agreed. The main takeaway despite my price-related grumbling is that some exciting lenses are in the pipeline for m4/3. Overpriced or not, that's reason for optimism.

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Great Bustard
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In reply to odl, Apr 12, 2012

odl wrote:

Actually, it doesn't, although that's the usual way, as using a higher ISO, as opposed to a lower ISO and pushing, results in lower noise with cameras that have non-ISOless sensors.

Which ones are those? Are the labelled on the body, or in the manual?

Cameras with sensors that have a flat read noise wrt to ISO, some of which are listed here:

http://www.sensorgen.info/

The ISO setting is irrelevant, except inasmuch as it results in less noise for cameras using non-ISOless sensors.

Again, how do we know? How does the average person know this stuff? You take a great deal for granted.

What I'm saying is that the usual method to keep the same DOF and shutter speed on different systems is to change the ISO. However, that is not the only way to do it, nor is it always the "best" way to do it, depending on several factors.

What's missing is people completely misunderstanding what the ISO control on the camera actually does.

No, it is missing from almost every time someone talks about equivalence and for people that are such science guys I find it puzzling that they would be putting the idea in peoples heads that you can stop down a FF lens and get the same image without adjusting other parameters such as ISO.

What I'm saying is that all you have to say is "same DOF and shutter speed" -- you do not need to add the condition of raising the ISO, although that is the usual way of doing it.

This site is getting to be rather well known:

http://www.sensorgen.info/

I doubt it, maybe here, but i doubt it is a blip on the radar of the millions of photographers using system cameras in the world.

Are those "millions of photographers" also discussing Equivalence?

Regardless, for those that don't know, they only need to ask.

Ask who?

The person who brings up the issue of ISOless and non-ISOless sensors.

What are they asking?

They should be asking, "How do you get the same DOF and shutter speed without changing the ISO, and why would you do that?"

Someone who doesnt know the difference between APSC and 135 or a camera phone and a point and shoot etc. How far up the learning curve will they be before they need answers to these questions?

Remember, Equivalence only comes into play when comparing different formats. So, how far up the learning curve should they be? As far as necessary to either understand the differences between different formats or astute enough to ask.

And aside from gear lust as measuring, how does it impact their photography to know what you can do with another camera system aside from let them know they have to spend more money.

As I keep saying, Equivalence comes up only when people are comparing different formats. So, the "gear lust" is already there before Equivalence even comes up.

Too often people are told here you "cant" do things on certain formats. Truth is you can do anything on any format all you need to know, is how to do it with what you have, not how it is done with something else.

I've lost count -- how many times have I said that Equivalence is only relevant when comparing different formats?

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Great Bustard
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In reply to odl, Apr 12, 2012

So Subject Isolation and DoF control. It is said it is harder on m43rds, but you can Isolate a full body with a slow zoom on m43rds, you can do it with a few of the primes, you can even do it with the 17mm f2.8 if you are shooting in the right space... But too often equivalence is brought in to confuse the entire subject, educating people what other equipment can do as long as they buy it... when all they need to be told is how to get closer to their goal with what they have.

There's something of a difference between maximizing the capabilities of your system and recognizing the advantages of another system.

Well I am glad you understood, my point remains the FF body would not have been equivalent to the EP2 for many reasons, 1 I couldnt stop down as far as I needed to...

You couldn't stop down to f/5.6?

...2 the performance of the sony at 6400 is poor and I had no room left for my shutterspeed.

That simply made the A850 the worse tool for the job at hand due to the less efficient sensor.

For equivalent photos (same perspective, framing, DOF, shutter speed, and display size), the differences between systems is minimal.

Why bother educating people then, aside form entertainment?

Because people seem to think, for example, that 75mm f/1.8 on mFT is the same thing as 150mm f/1.8 on FF. It is not. Not even close (unless you consider 2 stops to be "close").

If you need the same perspective, framing, DOF, and shutter speed.

But you almost never do, you shoot with what you have.

The reason I "almost never do" is because I usually prefer the more shallow DOF, and, when I want a deeper DOF, there is usually enough light in those scenes that I can comfortably use a lower shutter speed at base ISO, or I prefer the more shallow DOF over the more noisy photo.

But there are times I want a particular DOF and need a particular minimum shutter speed in a low light environment, and then, absolutely, I stop down and raise the ISO (my camera has a non-ISOless sensor).

Once you know what settings are equivalent, you can explore the options that one system offers that another doesn't.

No, people dont buy a FF camera then imagine what it would be on APSC, people dont shoot m43rds and imagine what they would be shooting in FF. They take the pictures with the cameras they have.

Among other examples, if one had mFT, and really, really, really wanted a 50 / 1 lens, then they might consider going FF and using a 100 / 2.

In the real world your camera has a noise signature, you know it. The "other" camera can do all sorts of things... But you dont have it... And for the case of the image in point the FF camera would not have performed better unless I sacrificed shutterspeed or DoF for my subjects. Your rule of thumb only applies in the lab. Because even in my example it is theoretical, I didnt have the a850, it wasnt even on the same continent.

I don't know what you're on about here. For equally efficient sensors, you will have the same noise for the same DOF and shutter speed. It's not theoretical -- it's been demonstrated with actual photos time and time again.

If the option for less noise (and the concomitantly more shallow DOF) or the option for a more shallow DOF is not desirable, then the photographer is likely better served with a smaller format.

But they will never know this, most people dont study the noise difference between formats... Most people dont even study photography, they just want to take nice pictures with what they have.

Then why are they comparing to other formats? Remember, Equivalence is only relevant when comparing different formats.

The bottom line is that 75mm f/1.8 on mFT doesn't do anything for you, in terms of the visual properties of the final photo, that 150mm f/3.6 on FF will not. Like I said -- no magic, just simple physics.

No, it will.

You are wrong in terms of the visual properties of the resulting photo. But, for sure, there will be operational differences (size, weight, price) that may be important (more important than any IQ differences, even).

Because your statement there makes people believe there is no downside (slower SS or higher ISO) or that it doesnt matter which FF body you are talking about... Not physics at all, your statements belong in a lab, or a physics classroom.

Now you're being dishonest, because earlier you even noted how I am always careful to say "for equally efficient sensors" rather than "it doens't matter which FF body you are talking about".

It would be of no help to someone who said "I have an EPL2 and I saw this picture, can I take it with my camera, I am using the 14-42 zoom" would they be better served by telling them how to get that type of shot with the equipment they have, what equipment they need to buy for their body to get "close enough" or what the equivalent of a 85mm f1.4 on a Nikon D4 would be on m43rds? I know which one makes sense, but I think you disagree.

Then they shouldn't be comparing to APS-C or FF, should they?

But you know, and I know, that there are those that will exclaim with excitement how the 75 / 1.8 is "equivalent to" a 150 / 1.8 on FF, as if they somehow "got the drop on FF" with the smaller sensor system. One wonders why such people don't recognize the "superiority" of the XZ-1 with its "28-112 / 1.8-2.5" lens.

I dont think anyone believes they "got the drop", they are getting the reach they want, in a package they want at the shutterspeed and ISO advatages they get for their camera.

There are no such "shutter speed and ISO advantages" as a function of format, just as a function of generation and efficiency of sensor.

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Great Bustard
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Re: No magic -- simple physics.
In reply to MAubrey, Apr 12, 2012

MAubrey wrote:

Well, at the very least, there is a sweet spot for equivalence around 50mm for μ43, where its physically possible (and reasonable) to have a f/1 lens (or f/1.1 in Voigtlander's case) which is then equivalent is DOF and AOV to a 100mm f/2 on a FF camera.

I have some interest in what might be the "sweet spot" as a function of format. However, we need to define the parameters for the "sweet spot". Size? Weight? Price? Resolution?

That is, I rather doubt a 50 / 1 on mFT would resolve nearly as well as a 100 / 2 on FF at the same DOF, with the FF sensor having at least as many pixels as the mFT sensor. I also very much doubt that a 50 / 1 will cost less or weigh less than a 100 / 2 for FF, but the overall system will most certainly cost less and weigh less for that singular body and lens.

Had the 75mm been f/1.4 we could perhaps say the same, since 150 f/2.8 is also viewed as rather fast for such an angle of view.

I'm thinking the 75 / 1.8 would be closer to that "Size/Weight/Price/Resolution" sweet-spot.

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Jun2
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Re: Always amazes me..
In reply to don_van_vliet, Apr 12, 2012

Give me break. This is not a proper product shooting session. This is a guy went to an event take a snap shot of a hot product. THis is pretty good.

Jun

don_van_vliet wrote:

How many photos of cameras have insufficient DoF to keep all detail sharp, or use an inappropriately close-up viewpoint distorting the geometry of the camera. Otherwise looks nice

The mount look similar in style to the Oly 45mm.

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odl
odl
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In reply to Great Bustard, Apr 12, 2012

Great Bustard wrote:

odl wrote:

Cameras with sensors that have a flat read noise wrt to ISO, some of which are listed here:

http://www.sensorgen.info/

So they are not labelled on the body or in the manual? Or even on the company website... You have to go hunting for that info...

What I'm saying is that the usual method to keep the same DOF and shutter speed on different systems is to change the ISO. However, that is not the only way to do it, nor is it always the "best" way to do it, depending on several factors.

Very straightforward.

What I'm saying is that all you have to say is "same DOF and shutter speed" -- you do not need to add the condition of raising the ISO, although that is the usual way of doing it.

But omitted most of the time.

Are those "millions of photographers" also discussing Equivalence?

You would think so wouldnt you, considering how often it is brought up here.

They should be asking, "How do you get the same DOF and shutter speed without changing the ISO, and why would you do that?"

Remember, Equivalence only comes into play when comparing different formats. So, how far up the learning curve should they be? As far as necessary to either understand the differences between different formats or astute enough to ask.

But people dont generally ask that, they generally ask how to achieve images with their equipment.

As I keep saying, Equivalence comes up only when people are comparing different formats. So, the "gear lust" is already there before Equivalence even comes up.

No, in this case people were trying to work out how much this lens would cost by looking at similar focal lengths, then someone said this:

. . . You make a good point. The Canon 135/2L goes for $1000. If this 75/1.8 can match the image characteristics of that lens, it will be truly a must have lens for m4/3.

Which is a compliment to the FF lens and was pretty much addressing effective focal length, and got back this:

then you should compare it to an f3.6/150mm lens for FF. Yawn, who would buy that ... even f/2.8 is considered slow nowadays for a FF 135mm, most brands have a 1.8 or 2.0 version.

I've lost count -- how many times have I said that Equivalence is only relevant when comparing different formats?

But it is mostly used to bash formats with smaller sensors. Even APSC to some degree (with people hating on not having a FF CSC).

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Great Bustard
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Re: (1)
In reply to odl, Apr 12, 2012

odl wrote:

Cameras with sensors that have a flat read noise wrt to ISO, some of which are listed here:

http://www.sensorgen.info/

So they are not labelled on the body or in the manual? Or even on the company website... You have to go hunting for that info...

Correct. Manufacturers also do not advertise the DR of the sensors -- that must be hunted for as well (also available at the site above).

What I'm saying is that the usual method to keep the same DOF and shutter speed on different systems is to change the ISO. However, that is not the only way to do it, nor is it always the "best" way to do it, depending on several factors.

Very straightforward.

As I said, misunderstanding what the ISO control does is every bit as misunderstood as what DR is.

What I'm saying is that all you have to say is "same DOF and shutter speed" -- you do not need to add the condition of raising the ISO, although that is the usual way of doing it.

But omitted most of the time.

Just as when saying "same DOF" we are presuming the same perspective, framing, display size, visual acuity, and viewing distance. These conditions are not explicity stated, as the implied conditions are common sense .

Are those "millions of photographers" also discussing Equivalence?

You would think so wouldnt you, considering how often it is brought up here.

DPR's forums are mainly gear oriented where discussions are usually technical in nature. Note how relatively few comment on some of the best pics I've seen:

http://forums.dpreview.com/forums/read.asp?forum=1022&message=41157535

in comparison to threads such as this.

They should be asking, "How do you get the same DOF and shutter speed without changing the ISO, and why would you do that?"

Remember, Equivalence only comes into play when comparing different formats. So, how far up the learning curve should they be? As far as necessary to either understand the differences between different formats or astute enough to ask.

But people dont generally ask that, they generally ask how to achieve images with their equipment.

Then these people would not be comparing to other formats, and, as a consequence, not discussing Equivalence.

As I keep saying, Equivalence comes up only when people are comparing different formats. So, the "gear lust" is already there before Equivalence even comes up.

No, in this case people were trying to work out how much this lens would cost by looking at similar focal lengths, then someone said this:

. . . You make a good point. The Canon 135/2L goes for $1000. If this 75/1.8 can match the image characteristics of that lens, it will be truly a must have lens for m4/3.

Which is a compliment to the FF lens and was pretty much addressing effective focal length, and got back this:

then you should compare it to an f3.6/150mm lens for FF. Yawn, who would buy that ... even f/2.8 is considered slow nowadays for a FF 135mm, most brands have a 1.8 or 2.0 version.

If "effective focal length" was all that was being compared, then one need not wish for the 75 / 1.8 -- the 40-150 / 4-5.6 has that focal length covered and then some, and considerably less cost (and size and weight?) as well.

Clearly, the speed of the lens is relevant in the comparison, and the same speed on different formats makes for very different results, just as the same focal length on different formats makes for very different results.

I've lost count -- how many times have I said that Equivalence is only relevant when comparing different formats?

But it is mostly used to bash formats with smaller sensors. Even APSC to some degree (with people hating on not having a FF CSC).

I can't speak for what "it is mostly used" for, I can only speak to why I often speak of it:

http://forums.dpreview.com/forums/read.asp?forum=1022&message=36379784

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odl
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In reply to Great Bustard, Apr 12, 2012

Great Bustard wrote:

There's something of a difference between maximizing the capabilities of your system and recognizing the advantages of another system.

But people trying to learn how to use their equipment are being told the advantages of another format over maximizing their system. You see this all the time with a "how do i blur the background" replied with a "use this lens" to which someone says "yeah well the exif says this is a 50mm f1.4 and your lens is an equivalent to a blah blah blah" that doesnt help the poster at all. He may not get everything he was after, but instead he got the feeling his equipment was inferior.

You couldn't stop down to f/5.6?

I could, but I would run out of ISO, or be shooting at 1/15 of a second with a moving child at 90mm.

That simply made the A850 the worse tool for the job at hand due to the less efficient sensor.

But it is FF, look at how many people here talk about FF advantages without adding the "efficient sensors comment" as if just being FF was good enough.

Because people seem to think, for example, that 75mm f/1.8 on mFT is the same thing as 150mm f/1.8 on FF. It is not. Not even close (unless you consider 2 stops to be "close").

It is, for Effective FL, ISO and for Shutter speed, three elements of photography, it isnt for noise performance and DoF, two other elements... who is correct? They both are, it is just you prioritize the last two (for reasons of preference looking at your work) over the first three. Others prioritize differently.

But there are times I want a particular DOF and need a particular minimum shutter speed in a low light environment, and then, absolutely, I stop down and raise the ISO (my camera has a non-ISOless sensor).

As will many others, and I dont mind shooting my a850 at 6400, noise is not a concern of mine in my personal shooting.

Among other examples, if one had mFT, and really, really, really wanted a 50 / 1 lens, then they might consider going FF and using a 100 / 2.

If they really really wanted that lens, sure. But that is not the context I see 95% of equivalence discussions.

In the real world your camera has a noise signature, you know it. The "other" camera can do all sorts of things... But you dont have it... And for the case of the image in point the FF camera would not have performed better unless I sacrificed shutterspeed or DoF for my subjects. Your rule of thumb only applies in the lab. Because even in my example it is theoretical, I didnt have the a850, it wasnt even on the same continent.

I don't know what you're on about here. For equally efficient sensors, you will have the same noise for the same DOF and shutter speed. It's not theoretical -- it's been demonstrated with actual photos time and time again.

You are talking about a theoretical matchup (rare) I am talking about when you have the two cameras side by side (rare). So I am saying the "other" camera can be anything you want it to be when you are making a theoretical point. But it rarely has any practical purpose.

Then why are they comparing to other formats? Remember, Equivalence is only relevant when comparing different formats.

In this case GB, they were trying to work out the price, and trying to justify it either being higher or lower. What has that got to do with DoF or Noise performance?

The bottom line is that 75mm f/1.8 on mFT doesn't do anything for you, in terms of the visual properties of the final photo, that 150mm f/3.6 on FF will not. Like I said -- no magic, just simple physics.

No, it will.

You are wrong in terms of the visual properties of the resulting photo. But, for sure, there will be operational differences (size, weight, price) that may be important (more important than any IQ differences, even).

Well, if I shoot my a850 at 3200 using a sigma 150mm macro lens at F5.6 and my OMD with the 75mm at F2.8 and ISO 800, I think the OMD would look a bit better for noise and detail. Swap cameras to a more efficient sensor and the FF wins. My point is that there are too many variables in the real world for the FF touts (generally speaking) to be so certain of the superiority of the format.

Because your statement there makes people believe there is no downside (slower SS or higher ISO) or that it doesnt matter which FF body you are talking about... Not physics at all, your statements belong in a lab, or a physics classroom.

Now you're being dishonest, because earlier you even noted how I am always careful to say "for equally efficient sensors" rather than "it doens't matter which FF body you are talking about".

But look at what I wrote GB, I said "your statement there" not every statement etc. And that happens all the time with other posters on Equiv. where they ignore ISO performance and equivalent sensor tech.

Then they shouldn't be comparing to APS-C or FF, should they?

They arent, not for equivalence purposes, they just want to know how to do it (or get close enough).

There are no such "shutter speed and ISO advantages" as a function of format, just as a function of generation and efficiency of sensor.

I meant in context of say, shooting my 40-150 at 75 and say F4.5 (guess) or shooting this at 75mm and at F1.8 I didnt mean in comparison to other formats, but the advantages of shooting with a faster lens. For them they get to use a lower ISO or a higher SS, both valuable. That is why they disagree with equivalence, as to say it is the same as a slower aperture flys in the face of the advantages they see with their cam (no matter what it means for the other cameras)... You get my point, I know you do.

Ab

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odl
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In reply to Great Bustard, Apr 12, 2012

Great Bustard wrote:

Just as when saying "same DOF" we are presuming the same perspective, framing, display size, visual acuity, and viewing distance. These conditions are not explicity stated, as the implied conditions are common sense .

However you ran a list of similarities, I am saying a difference is omitted not a similarity. And it is an important difference.

But people dont generally ask that, they generally ask how to achieve images with their equipment.

Then these people would not be comparing to other formats, and, as a consequence, not discussing Equivalence.

SO equivalence is a punishment I get it now But seriously, they want to know how to take these kinds of pictures, not how it could be taken if they owned someone elses equipment.

If "effective focal length" was all that was being compared, then one need not wish for the 75 / 1.8 -- the 40-150 / 4-5.6 has that focal length covered and then some, and considerably less cost (and size and weight?) as well.

No, they were thinking about an 85mm f1.8 on FF as a comparison which then shifted to a longer focal length for the equivalent FL. And as you know 43rds optics have to perform better just to keep up, so there is some merit that a 75mm on m43rds is not really the same optics as an 85mm on FF if you get my drift.

Clearly, the speed of the lens is relevant in the comparison, and the same speed on different formats makes for very different results, just as the same focal length on different formats makes for very different results.

So does the quality of the glass... Not all 50mm f1.4 lenses cost $250 either. That was the gist of the conversation.

I can't speak for what "it is mostly used" for, I can only speak to why I often speak of it:

You enjoy a good discussion, and this subject is one that you are interested in. However the Equiv. argument is used so much more than just by you, and not always in a fair context. Hence equiv. has become such a dirty word.

Ab

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Re: Either way, a must-buy
In reply to Great Bustard, Apr 12, 2012

Great Bustard wrote:

. . . You make a good point. The Canon 135/2L goes for $1000. If this 75/1.8 can match the image characteristics of that lens, it will be truly a must have lens for m4/3.

It won't be able to "math the image characteristics of that lens" when "that lens" is used below f/3.6 on FF, and I would bet against it resolving as well at the same DOF.

Yes, by the time the 135L gets past f2.8 on FF it is well into the "angels dancing on the head of a pin" MTF twilight zone. The 75/1.8 should compare favorably with the classic EF 135/2.8 on FF... but the cost will be 3x or so higher. Design complexity and material costs would be a modern 150/3.6, not the 135L. My parents have a f0.95 standard-medium tele zoom on their super-8mm camera... and the whole package was a couple hundred dollars (with the camera!). Kodak could have charged a mint using the creative focal-length-mulitplier-irrespecitive-of-format math so common here.

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Great Bustard
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Re: (2)
In reply to odl, Apr 12, 2012

odl wrote:

There's something of a difference between maximizing the capabilities of your system and recognizing the advantages of another system.

But people trying to learn how to use their equipment are being told the advantages of another format over maximizing their system. You see this all the time with a "how do i blur the background" replied with a "use this lens" to which someone says "yeah well the exif says this is a 50mm f1.4 and your lens is an equivalent to a blah blah blah" that doesnt help the poster at all. He may not get everything he was after, but instead he got the feeling his equipment was inferior.

I see "how do I blur the background" posts all the time. The answers I typically see are:

  • Frame tighter

  • Use a longer focal length

  • Use greater subject-background separation

You couldn't stop down to f/5.6?

I could, but I would run out of ISO, or be shooting at 1/15 of a second with a moving child at 90mm.

That simply made the A850 the worse tool for the job at hand due to the less efficient sensor.

But it is FF, look at how many people here talk about FF advantages without adding the "efficient sensors comment" as if just being FF was good enough.

Because it's naturally assumed that we're talking about sensors of the same generation, which are usually rather close in terms of efficiency.

Because people seem to think, for example, that 75mm f/1.8 on mFT is the same thing as 150mm f/1.8 on FF. It is not. Not even close (unless you consider 2 stops to be "close").

It is, for Effective FL, ISO and for Shutter speed, three elements of photography, it isnt for noise performance and DoF, two other elements... who is correct? They both are, it is just you prioritize the last two (for reasons of preference looking at your work) over the first three. Others prioritize differently.

Except, as a photographer, I'm interested in the final photo. And the elements of the final photo that matter are perspective, framing, DOF, motion blur, and noise, not focal length and ISO.

Then why are they comparing to other formats? Remember, Equivalence is only relevant when comparing different formats.

In this case GB, they were trying to work out the price, and trying to justify it either being higher or lower. What has that got to do with DoF or Noise performance?

Because the aperture of the lens, and thus the DOF/noise it will produce in the photo, has everything to do with the price.

The bottom line is that 75mm f/1.8 on mFT doesn't do anything for you, in terms of the visual properties of the final photo, that 150mm f/3.6 on FF will not. Like I said -- no magic, just simple physics.

No, it will.

You are wrong in terms of the visual properties of the resulting photo. But, for sure, there will be operational differences (size, weight, price) that may be important (more important than any IQ differences, even).

Well, if I shoot my a850 at 3200 using a sigma 150mm macro lens at F5.6 and my OMD with the 75mm at F2.8 and ISO 800, I think the OMD would look a bit better for noise and detail.

Noise, for sure (the OMD has a more efficient sensor, and we're talking about the same DOF and shutter speed). Detail, I can't say.

Swap cameras to a more efficient sensor and the FF wins. My point is that there are too many variables in the real world for the FF touts (generally speaking) to be so certain of the superiority of the format.

The "superiority of the format" is based on cameras of the same generation, and in terms of IQ only.

Because your statement there makes people believe there is no downside (slower SS or higher ISO) or that it doesnt matter which FF body you are talking about... Not physics at all, your statements belong in a lab, or a physics classroom.

Now you're being dishonest, because earlier you even noted how I am always careful to say "for equally efficient sensors" rather than "it doens't matter which FF body you are talking about".

But look at what I wrote GB, I said "your statement there" not every statement etc. And that happens all the time with other posters on Equiv. where they ignore ISO performance and equivalent sensor tech.

I'm sure there are stupid people who will say FF is superior no matter what. But they are stupid people.

There are no such "shutter speed and ISO advantages" as a function of format, just as a function of generation and efficiency of sensor.

I meant in context of say, shooting my 40-150 at 75 and say F4.5 (guess) or shooting this at 75mm and at F1.8 I didnt mean in comparison to other formats, but the advantages of shooting with a faster lens. For them they get to use a lower ISO or a higher SS, both valuable. That is why they disagree with equivalence, as to say it is the same as a slower aperture flys in the face of the advantages they see with their cam (no matter what it means for the other cameras)... You get my point, I know you do.

Honestly, no, I do not get your point. 75mm f/1.8 on mFT does nothing for you (in terms of the IQ of the photo) that 150mm f/3.6 on FF will not. Do I have to specify that I'm talking about cameras of the same generation? Do I have to specify that I mean digital, not film? Do I have to specify that there is no 150 / 3.6 for FF?

Or do you know what I mean?

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Great Bustard
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Re: (1)
In reply to odl, Apr 12, 2012

odl wrote:

Great Bustard wrote:

Just as when saying "same DOF" we are presuming the same perspective, framing, display size, visual acuity, and viewing distance. These conditions are not explicity stated, as the implied conditions are common sense .

However you ran a list of similarities, I am saying a difference is omitted not a similarity. And it is an important difference.

Same DOF and shutter speed on different formats naturally implies different ISOs -- it doesn't need to be stated. That said, it doesn't require different ISOs.

But people dont generally ask that, they generally ask how to achieve images with their equipment.

Then these people would not be comparing to other formats, and, as a consequence, not discussing Equivalence.

SO equivalence is a punishment I get it now But seriously, they want to know how to take these kinds of pictures, not how it could be taken if they owned someone elses equipment.

Just as often, if not more so, they mean that, for example, 300mm f/2.8 on 4/3 "really is" 600mm f/2.8 on FF:

http://forums.dpreview.com/forums/read.asp?forum=1022&message=39410248

because they don't understand what exposure is, how it differs from total light, and what role these quantities play in the visual properties of the final photo.

If "effective focal length" was all that was being compared, then one need not wish for the 75 / 1.8 -- the 40-150 / 4-5.6 has that focal length covered and then some, and considerably less cost (and size and weight?) as well.

No, they were thinking about an 85mm f1.8 on FF as a comparison which then shifted to a longer focal length for the equivalent FL. And as you know 43rds optics have to perform better just to keep up, so there is some merit that a 75mm on m43rds is not really the same optics as an 85mm on FF if you get my drift.

I missed the posts where they compared the 75 / 1.8 on mFT to an 85 / 1.8 on mFT. For sure, Equivalence plays no role here:

josephjamesphotography.com/equivalence/index.htm#quick

  • Equivalence is only relevant when comparing different formats. For example, if we are comparing the performance of a 50mm lens designed for 135 (35mm FF) to a 50mm lens designed for APS-C or 4/3, both lenses being used on the same camera, Equivalence does not come into play.

Clearly, the speed of the lens is relevant in the comparison, and the same speed on different formats makes for very different results, just as the same focal length on different formats makes for very different results.

So does the quality of the glass... Not all 50mm f1.4 lenses cost $250 either. That was the gist of the conversation.

Sure -- like I said, I missed the comparison of the 75 / 1.8 to the 85 / 1.8, both being used on mFT.

You enjoy a good discussion, and this subject is one that you are interested in. However the Equiv. argument is used so much more than just by you, and not always in a fair context. Hence equiv. has become such a dirty word.

It's as easy as 1, 2, and 3 to set straight those that misrepresent Equivalence:

josephjamesphotography.com/equivalence/index.htm#superduperquick
josephjamesphotography.com/equivalence/index.htm#superquick
josephjamesphotography.com/equivalence/index.htm#quick

I'll catch up with ya later -- I'm off to sleep.

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Melbourne Park
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One thing barely mentioned with FF, and R&D costs
In reply to Great Bustard, Apr 12, 2012

One thing barely mentioned with FF sensors and lenses, is that IMO there is more distortion out wide with FF prime lenses ... I presume too, that the lack of telecentricity of m43 does not assist with their sensor performances either.

Oh and R&D costs, and economy of scale arguments:

R&D costs: having read an article with the owner of Sigma, he said that these days, they design their lenses using software, and that lens design is much much easier than it used to be. Hence the argument about R&D costs being spread on fewer lenses is I reckon untrue.

Economy of Scale: Also, with the sales of m43 being high, and there being less lenses available for m43, the scale of R&D costs would be spread over large numbers of lenses anyway.

And further, lenses I believe - from watching a movie of Canon making an expensive prime tele lens - lens are a batch process. They are not production line massed produced. Hence the economy of scale argument has less weight, because batch process costs are much less effected by production line high volume economies.

Hence, the high prices for m43 lenses, is likely profit ... IMO at least.

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technic
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Re: (1)
In reply to odl, Apr 12, 2012

odl wrote:

then someone said this:

. . . You make a good point. The Canon 135/2L goes for $1000. If this 75/1.8 can match the image characteristics of that lens, it will be truly a must have lens for m4/3.

It CAN'T match the image characteristics of that lens, becaue the 135/2L has several stops better DOF control. On top of that, the Canon 2/135 is optically close to perfect and expecting the 1.8/75 to be better is a pipe dream IMHO.

Which is a compliment to the FF lens and was pretty much addressing effective focal length, and got back this:

then you should compare it to an f3.6/150mm lens for FF. Yawn, who would > > > buy that ... even f/2.8 is considered slow nowadays for a FF 135mm, most > > > brands have a 1.8 or 2.0 version.

a reply to what was suggested above, 'match the image characteristics'. DOF control / bokeh is an important part of that.

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technic
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Re: No magic -- simple physics.
In reply to Great Bustard, Apr 12, 2012

Great Bustard wrote:

The bottom line is that 75mm f/1.8 on mFT doesn't do anything for you, in terms of the visual properties of the final photo, that 150mm f/3.6 on FF will not. Like I said -- no magic, just simple physics.

exactly, that's why I brought it up.

But you know, and I know, that there are those that will exclaim with excitement how the 75 / 1.8 is "equivalent to" a 150 / 1.8 on FF, as if they somehow "got the drop on FF" with the smaller sensor system. One wonders why such people don't recognize the "superiority" of the XZ-1 with its "28-112 / 1.8-2.5" lens.

yes, but it seems a futile discussion as you can see it repeated here ad nauseam on a dialy basis

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