Equivalence: read this, then argue

[Christof21]

The debate is about relevance.

It is strongly relevant in my opinion. Just because equivalent settings correspond to equivalent optical systems: same dof, same fov, same quantity of light.

It does not say that sensor efficiency is the same. But did you notice that even for a similar format, sensors could perform differently ?

The other issue with these debates is the glaringly obvious point that all sensors are not equivalent. Noise, DR and other considerations a moot as soon as you pick a Canon sensor and compare it with a Sony one.

Again what you say is true even for a similar format. But equivalence normalizes aperture, iso, focal. These numbers are so dependent on sensor format that they should be given for a 35mm equivalent format. It is strongly relevant in my opinion !! Optically, it is !.

How would compare a Fuji/Panasonic organic sensor with a regular one? It could have more than a stop improvement in QE.

What equivalence says is that if you build an APSC organic sensor and a FF organic sensor, there is great chance that the difference will be more than 1 stop.

There will be no surprise. Whatever the technology is, the FF sensor receives 2.25 more light (with the same aperture). The photon noise for instance will be more than 1 stop better, it does not depend on technology.

For practical reason, you can imagine that a FF sensor would be less efficient than an APS-C (because the latest technology would be applied first with the smaller sensor). But a FF sensor is mainly an APS-C sensor, but larger.

The reasons for switching from APSC to FF would be the same, even with organic sensors.

The only advantage which may change is dynamic range. Sensors may be not limited anymore in DR, I am sure that in the future new technologies will allow this.

Similarly you cannot compare Canon lenses with Fuji lenses and try and work out what is equivalent to what. There will be variations of more than a stop in either direction depending on performance characteristics (like what is the useful max aperture of a given lens?)

Since no two cameras are ever directly comparable, this wonderful technical diatribe is largely irrelevant in the real world. I would say you could pick a combination of lenses and an APSC camera that would give you WORKING equivalence over many FF setups over most of the important shooting scenarios. Fuji are closer than most because of the quality of the primes, which are very well behaved wide open, unlike most of my Nikkors.

I use a D800 mainly because it has 36MP, not because its FF. All things being equal FF will give you more resolution for a given MP count provided your lenses have good edge performance. However if the Xpro2 has a 24MP organic filter sensor, it may well outperform the D800. The lenses are certainly good enough.

 

[mr moonlight]

Fact is, equivalent cameras and lenses don't exist.

 

[Rod McD]

Hi again,

I posted my main thoughts on this topic earlier today but it came back to me with an interesting observation a little later this afternoon. This is kind of an aside .......

I was using a TS adapter and it occurred to me just how wonderful it is that with movements, you can largely chuck this debate about equivalence out the window....... The whole debate is the product of a having a vertical plane of focus parallel to the sensor and achieving DOF by stopping the lens down. But apply a little tilt to lay the plane of focus onto the subject, and your image just slides into focus all over. Beautiful. And that's at maximum aperture. You can stop down to get to the lens' optimal aperture if you need to. DOF for a planar subject is virtually independent of sensor size and aperture.

That is IF, of course, your subject is suitable....... Many aren't. But if it IS suitable, and you've got movements, the bigger sensor wins.

Obviously I'm not suggesting that everyone should use TS lenses all the time. But interesting, eh? I guess old view camera users just see things from a different perspective .

Cheers, Rod

 

[57LowRider]

Are you the charlatan great bustard touting for business?

Just read this and the following post and I'm kind of appalled that people feel the need do this kind of thing - and I put my hand up now and say that I think this link came from one of his posts.

Nonetheless, despite the provenance, I find the linked article illuminating in a number of areas. What it has let me see is that Fuji have been pretty damn smart in how they've squeezed extra performance out of a sensor common to other brands' cameras. Is the magic in the CFA or microlensing? It makes me both wonder at their engineering and applaud whatever they did.

Clearly Fuji chose APS-C for good reasons, rather than randomly sticking a pin in a list of formats. They had a brief based on many parameters (including size and cost) and have created something of very high quality that many more of us can enjoy than had it been a larger, more expensive format. I feel that I'm getting a lot of bang for my buck with this system; long may it thrive.

This is not to say that I think other brands are poo, which is a popular pastime on DPR, just that Fuji's particular set of compromises really sit well with me. Sony's A7r really piqued my interest for a while; small body, great IQ, lots of pixels for big prints and terrific dials and a superb set of system lenses... no, wait... scrub the last two... and there my interest died. Had they played Fuji at their own game, they might have killed the X system though.

 

[57even]

The debate is about relevance.

It is strongly relevant in my opinion. Just because equivalent settings correspond to equivalent optical systems: same dof, same fov, same quantity of light.

It does not say that sensor efficiency is the same. But did you notice that even for a similar format, sensors could perform differently ?

The other issue with these debates is the glaringly obvious point that all sensors are not equivalent. Noise, DR and other considerations a moot as soon as you pick a Canon sensor and compare it with a Sony one.

Again what you say is true even for a similar format. But equivalence normalizes aperture, iso, focal. These numbers are so dependent on sensor format that they should be given for a 35mm equivalent format. It is strongly relevant in my opinion !! Optically, it is !.

How would compare a Fuji/Panasonic organic sensor with a regular one? It could have more than a stop improvement in QE.

What equivalence says is that if you build an APSC organic sensor and a FF organic sensor, there is great chance that the difference will be more than 1 stop.

There will be no surprise. Whatever the technology is, the FF sensor receives 2.25 more light (with the same aperture). The photon noise for instance will be more than 1 stop better, it does not depend on technology.

The camera may receive 2.5X more light, but it won't necessarily capture it.

For practical reason, you can imagine that a FF sensor would be less efficient than an APS-C (because the latest technology would be applied first with the smaller sensor). But a FF sensor is mainly an APS-C sensor, but larger.

But sensors are not all the same. I was comparing an organic APSC sensor with a standard FF one.

The reasons for switching from APSC to FF would be the same, even with organic sensors.

You missed my point. Unless someone makes a FF organic sensor, the comparison is moot.

The only advantage which may change is dynamic range. Sensors may be not limited anymore in DR, I am sure that in the future new technologies will allow this.

Again, you didn't read my post. I said that in the real world we are comparing cameras and lenses which perform differently and therefore the effect of the 2.5X more light may not end up being a full stop, or it may be more, depending on the lenses used and the efficiency of the sensor.

If you compare sensors of exactly equal design and construction and lenses with comparable performance, then the theoretical comparison is valid. If you don't, there is considerable variation in the result. Like I said, most of my Nikon lenses do not perform very well wide open, because of focus shifts and fringing, so my FF body is generally limited to a smaller aperture for similar quality.

We should talk about system equivalence, not sensors. The Sony A7 for instance has relatively slow lenses, so the advantage of the larger sensor is not one stop.

 

[57even]

Fact is, equivalent cameras and lenses don't exist.

Exactly.

 

[Eoanthropus]

Seems fairly good overall, but he's technically incorrect about DOF.

hyperfocal distance = focal length ^2 / (f/stop * circle of confusion)

Make the crop factor adjustments for focal length (angle of view constant) and aperture, but that value for circle of confusion remains different for different formats. There's no circle of confusion "crop factor" and so smaller format cameras do deliver more DOF that larger format cameras.

Could you check before posting ?? You are completely inventing ? Actually he is right. You have dof calculators to check..

At equivalent settings, the focal length is multiplied by c (crop factor). Both the f/stop and circle of confusion are multiplied by c. So the hyperfocal distance is the same.

Looks like we're both wrong. And how you managed to be so sloppy as to blurt out that incorrect info without checking first -- seriously you couldn't Google it or something?

The hyperfocal distance is the same if you apply the crop factor to the aperture as well as focal length. However the crop factor is not applied to the circle of confusion as you erroneous claimed. The magnification decrease from using smaller formats requires a smaller circle of confusion.

There is then a pragmatic equivalence at play here which photographers have always known. In comparing for example FF with MFT where the crop factor is 2; out in the field using those cameras the FF camera has to be stopped down 2 additional f/stops to produce the same hyperfocal distance when lenses of matching angle of view are used. If equivalent exposures are set on the two cameras the smaller format camera delivers more DOF. If equivalence really is the subject here then practical equivalence matters as well.

 

[rhlpetrus]

Agreed, people love useless arguments. It's much more important to learn about exposure and how to deal with PP issues than about this equivalence aspects Of different formats.

 

[slimandy]

I went to dinner last night with much-loved relatives, rejecting the X-T1, battery grip and 56 in favour of the X-E1 and 35;

What has this got to do with equivalence?

 

[57LowRider]

I went to dinner last night with much-loved relatives, rejecting the X-T1, battery grip and 56 in favour of the X-E1 and 35;

What has this got to do with equivalence?

It's tenuous, I agree; I was trying to make a point about compromises that one is happy with.

 

[b0k3h]

If those who think small sensors are limiting their photographic potential, and/or those who think large sensors are giving them a leg up on output.....

...post pics of their galleries to see how much the camera/sensor really matters to their perceived insufficiency or superiority

 

[dark13star]

I know for a fact that the limiting factor in my photography is behind the camera. At least with small sensors I'm motivated to carry my camera and shoot more.

Rich

 

[Christof21]

Seems fairly good overall, but he's technically incorrect about DOF.

hyperfocal distance = focal length ^2 / (f/stop * circle of confusion)

Make the crop factor adjustments for focal length (angle of view constant) and aperture, but that value for circle of confusion remains different for different formats. There's no circle of confusion "crop factor" and so smaller format cameras do deliver more DOF that larger format cameras.

Could you check before posting ?? You are completely inventing ? Actually he is right. You have dof calculators to check..

At equivalent settings, the focal length is multiplied by c (crop factor). Both the f/stop and circle of confusion are multiplied by c. So the hyperfocal distance is the same.

Looks like we're both wrong.

Really ? If it can make you happy believing it, no problem .

And how you managed to be so sloppy as to blurt out that incorrect info without checking first -- seriously you couldn't Google it or something?

The hyperfocal distance is the same if you apply the crop factor to the aperture as well as focal length. However the crop factor is not applied to the circle of confusion as you erroneous claimed. The magnification decrease from using smaller formats requires a smaller circle of confusion.

No need to make so much effort,. You omit to mention that you claimed in a second post quickly deleted that me and the author were both wrong, you even persisted in your error !!! You seem to be really confused.

You should thank me for correcting a wrong post. You learned something at least, see the positive side.

The author of the article did a great job, very detailed and instructive. You were positive saying that he was wrong, without expressing any doubts and asking questions.

There is then a pragmatic equivalence at play here which photographers have always known. In comparing for example FF with MFT where the crop factor is 2; out in the field using those cameras the FF camera has to be stopped down 2 additional f/stops to produce the same hyperfocal distance when lenses of matching angle of view are used. If equivalent exposures are set on the two cameras the smaller format camera delivers more DOF. If equivalence really is the subject here then practical equivalence matters as well.

 

[Eoanthropus]

Seems fairly good overall, but he's technically incorrect about DOF.

hyperfocal distance = focal length ^2 / (f/stop * circle of confusion)

Make the crop factor adjustments for focal length (angle of view constant) and aperture, but that value for circle of confusion remains different for different formats. There's no circle of confusion "crop factor" and so smaller format cameras do deliver more DOF that larger format cameras.

Could you check before posting ?? You are completely inventing ? Actually he is right. You have dof calculators to check..

At equivalent settings, the focal length is multiplied by c (crop factor). Both the f/stop and circle of confusion are multiplied by c. So the hyperfocal distance is the same.

Looks like we're both wrong.

Really ? If it can make you happy believing it, no problem .

And how you managed to be so sloppy as to blurt out that incorrect info without checking first -- seriously you couldn't Google it or something?

The hyperfocal distance is the same if you apply the crop factor to the aperture as well as focal length. However the crop factor is not applied to the circle of confusion as you erroneous claimed. The magnification decrease from using smaller formats requires a smaller circle of confusion.

No need to make so much effort,. You omit to mention that you claimed in a second post quickly deleted that me and the author were both wrong, you even persisted in your error !!! You seem to be really confused.

You should thank me for correcting a wrong post. You learned something at least, see the positive side.

The author of the article did a great job, very detailed and instructive. You were positive saying that he was wrong, without expressing any doubts and asking questions.

There is then a pragmatic equivalence at play here which photographers have always known. In comparing for example FF with MFT where the crop factor is 2; out in the field using those cameras the FF camera has to be stopped down 2 additional f/stops to produce the same hyperfocal distance when lenses of matching angle of view are used. If equivalent exposures are set on the two cameras the smaller format camera delivers more DOF. If equivalence really is the subject here then practical equivalence matters as well.

I admitted that I was wrong.

It does make me happy knowing that you were also wrong.

It likewise makes me happy to have been able to correct your error.

It likewise makes me happy that you have not and can not refute my correction of your error. Given your prevaricating now I assume you would have if you could.