nigelht

nigelht

Joined on Sep 2, 2012

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Total: 48, showing: 1 – 20
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On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

kociasek: The caption under the photograph of the four lenses seems to be wrong. It says:
"These four lenses are all 85mm equivalent F1.2s. However, this does not mean they're all 85mm F1.2 equivalent."
Unless I'm mistaken, "equivalent" should be dropped from the first sentence.

@bobn2 Not if you are already at your camera's ISO limit

@alberto Yes, it's equivalence in DoF and theoretical noise. So just state that.

Sony, 10.4-37.1mm F1.8-4.9 lens (28-100mm FoV F4.8-13.2 DoF equiv)

Noise, as seen in the provided examples, is not quite what you would expect from the numbers. Crop sensors noisier than FF sensors is a sufficiently accurate description without testing the specific models being compared.

Direct link | Posted on Jul 12, 2014 at 02:09 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Louschro: What is the advantage of using a camera with a larger sensor? You can take any (!) equivalent picture, that a camera with a smaller sensor can take. But additionally there is the potential to take (non equivalent) pictures with less DOF and less noise, which cameras with smaller sensor can't take. You have decide: Is this potential so important for you, that you would accept the burden to always carry the larger and heavier system?

Very often larger sensors have more resolution. How does it affect equivalence? In this case the equivalence of noise is not given. Instead the pictures will have more noise due to the smaller pixels.

@cheng bao

I can get the shot with a 50/1.2 just fine on m43 at the same shutter speed and ISO. It'll just be more noisy but not under exposed.

Direct link | Posted on Jul 12, 2014 at 00:43 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Sven44: Heh, I've just spotted the following on a review of Fuji's new lens (which I'm just a little bit excited by....):

"We've been shooting with the Fujinon XF 56mm F1.2 R - the fast 85mm equivalent prime lens for Fujifilm's X mount mirrorless cameras. Its F1.2 aperture means it gives similarly shallow depth-of-field to an 85mm F1.8 lens on a full frame body, making it an useful portrait lens"

Makes 100% perfect sense to me, and a great opening paragraph to the review. Does anyone not see it that way? How else should hey have described it?

Nigelht? Maybe a "56mm 1.2 lens which you're going to mount on a normal camera but then you're going to take a crop of it so you have the FOV of an 85mm lens, but let's not talk about the depth of field or sensor gain for that matter because no-one wants to have to multiply anything by 1.5..."?

Sven, stop being an ass. The paragraph reads fine the way it is because it tells you the equivalence is in terms of DoF.

Direct link | Posted on Jul 12, 2014 at 00:40 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Richard Butler: It's been suggested to me that people would be happier if we used the term 'Equivalent F-number' rather than 'Equivalent Aperture.' Is this the case?

If you really want a new term call it "equivalent noise/DOF value" or something descriptive.

Direct link | Posted on Jul 12, 2014 at 00:38 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

kociasek: The caption under the photograph of the four lenses seems to be wrong. It says:
"These four lenses are all 85mm equivalent F1.2s. However, this does not mean they're all 85mm F1.2 equivalent."
Unless I'm mistaken, "equivalent" should be dropped from the first sentence.

@richard

Not when you are at 12800 and wide open already.

Given your equivalence numbers can you make the shot that a RX100 II can take at f1.8 ISO 12,800 1/300 on a D5300 or D800 at 1/300?

Parties, sports, dance, weddings, etc. 12,800 is a bit extreme but looking at your studio shot it would be a keeper if that was what the light was.

Forget noise and DoF for a moment. Can your equivalence numbers tell me if I can get the shot? Or do they deeply imply that I cannot.

Direct link | Posted on Jul 12, 2014 at 00:32 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Sven44: Here's what I don't get. Pretty much everyone (with the possible exception of nigelht - I'm not sure..) appreciates the concept of equivalent focal length.

("Wow! 5-20mm! What an incredibly wide angle zoom lens! Oh wait. It's a really small sensor. So for FOV that's equivalent to 25-100. Well that's ok - a useful range.")

Yet when *exactly the same reasoning* is applied to aperture and ISO,

("Wow! f/1.4! And ISO 200! Oh wait, it's a small sensor. So for DOF and exposure and noise, that's about equivalent to f/2.8 and ISO 800. No problem, pretty usable."),

some people's hackles are raised and they just can't accept the concept at all.

Weird.

"Yet when *exactly the same reasoning* is applied to aperture and ISO,

("Wow! f/1.4! And ISO 200! Oh wait, it's a small sensor. So for DOF and exposure and noise, that's about equivalent to f/2.8 and ISO 800. No problem, pretty usable."),

some people's hackles are raised and they just can't accept the concept at all."

Because this is a false equivalence.

Take the RX100 II example. We know you can capture a properly exposed (or at least usable) image at ISO 12,800 f4.3 1/30 at 31.48mm focal lenght (85mm crop equiv) because there's one in the review.

Can you capture a properly exposed shot with a D5300 at the f11ish equivalence value and 1/30? You need 2.7 stops more ISO. You have 1. You can go longer on the exposure. What if its your kids hockey game and you need 1/300 to stop action?

The f4.8-13.2 equivalence tells you about DoF but misleads you on what pictures you can take. It's STILL a F1.8-4.9 lens and neither noise nor DoF matter if you can't get the shot.

The RX100 can.

Direct link | Posted on Jul 12, 2014 at 00:24 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

kociasek: The caption under the photograph of the four lenses seems to be wrong. It says:
"These four lenses are all 85mm equivalent F1.2s. However, this does not mean they're all 85mm F1.2 equivalent."
Unless I'm mistaken, "equivalent" should be dropped from the first sentence.

"At which point, saying:

Olympus, 6-24mm F1.8-2.5 lens (28-112mm F8.4-11.7 equiv)

Sony, 10.4-37.1mm F1.8-4.9 lens (28-100mm F4.8-13.2 equiv)

Tells you something useful, doesn't it? (Being able to see how they progress is arguably even more useful."

Yes, that tells you something useful relative to each other w.r.t. DOF.

It is still misleading in terms of exposure. The Olympus may be noisy in getting a dim shot but it doesn't act like a f8.4 lens that can't be properly exposed at the desired shutter speed.

Same for the Sony. At ISO 12,800 f1.8 you'll still get a properly exposed shot that can't be done with a f4.8 and a D5300 and probably not with a D800.

Your RX100 II studio shot at ISO 12,800 was at 1/30 and f4.3. Can you make that shot at f11ish at 1/30 with the D800?

If not then it's not really equivalent is it?

Direct link | Posted on Jul 11, 2014 at 23:58 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Easycass: Perhaps a simple question may help decide if this is useful or not: -

Let's say my photo assistant has an APS-C camera with a crop-factor of 1.5, and I have a FF frame camera. We agree that we will take the same shots of a model, in that the end results of the raw image files must have the same angle of view, same exposure, same framing and same depth-of-field. We also decide that the APS-C camera will use f/1.4 and a 56mm lens, in aperture priority.

We essentially want 'equivalent' photos.

So, the question is, what settings do I need for my FF camera/lens to match the APS-C images?

From what I see, I might get two answers to this: -

1) a lens focal length plus aperture value to use, or
2) opinions expressing that it is unimportant, or that f1.4 is f1.4 is f1.4, or it is too confusing, or I don't need any calculations, etc...

For me, I would certainly find the first answer to be more helpful... Possibly a use for some calculations after all?

Okay, let me have it...!

"So, the question is, what settings do I need for my FF camera/lens to match the APS-C images?"

The real question is why would you want to in the first place.

The answer is 54mm f1.4 and crop.

Direct link | Posted on Jul 11, 2014 at 23:23 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

kociasek: The caption under the photograph of the four lenses seems to be wrong. It says:
"These four lenses are all 85mm equivalent F1.2s. However, this does not mean they're all 85mm F1.2 equivalent."
Unless I'm mistaken, "equivalent" should be dropped from the first sentence.

"It seems much more likely that I'd use an 85mm on FF and a 32mm on 1"-type, shooting at the same distance (since they offer the same field-of-view), and it's easier for me to imagine than it is to try to think about shooting a 32mm lens on FF but standing at portrait-shooting distance, then trying to think of where the crop would be."

Then you will largely be looking for an nonexistent fast lens in a crop format most of the time if you're shooting an 85mm f1.8 FF.

And if that's your intent then all the equivalence calculations in your article should be in the opposite direction.

Your examples should be "I am taking a portrait using a 85mm f1.8 wide open...what equivalent Nikon 1/m43 lens should I choose?"

"Cropping an image also does change the per-image noise performance, if you view/print both images at the same size."

Not in comparison to what you get on a crop sensor.

Direct link | Posted on Jul 11, 2014 at 19:04 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

kociasek: The caption under the photograph of the four lenses seems to be wrong. It says:
"These four lenses are all 85mm equivalent F1.2s. However, this does not mean they're all 85mm F1.2 equivalent."
Unless I'm mistaken, "equivalent" should be dropped from the first sentence.

"What's more funny is your refusal to acknowledge that cropping is not the only, or usual, manner to achieve an Equivalent photo (it would only be done in the case of a focal length or magnification limited scenario)."

And when do you EVER want to achieve an equivalent photo?

Never.

So there is no "usual manner" to achieve an equivalent photo.

And if there was a usual manner then cropping would be it because ITS IN THE NAME "CROP SENSOR". Who decided your way was the "usual" way because the guy who coined the name didn't get the memo.

You guys insist on turning something simple into something absurdly complex.

Q: How do I determine the equivalence of a crop format image and a FF format image?
A: Take the same picture with FF camera using the same lens and crop just like the name says.

Direct link | Posted on Jul 11, 2014 at 18:41 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

kociasek: The caption under the photograph of the four lenses seems to be wrong. It says:
"These four lenses are all 85mm equivalent F1.2s. However, this does not mean they're all 85mm F1.2 equivalent."
Unless I'm mistaken, "equivalent" should be dropped from the first sentence.

"Question: when would the user of the larger format ever *intentionally* use the same settings as the user of the smaller format and crop to the same framing when they were not focal length or magnification limited?"

When would anyone use the equivalence settings you propose?

Never. He will never attempt to replicate what a crop sensor will do. He will appropriately compose the shot with the lenses he has.

The only time you do this evaluation is when you want to know if it's worth switching from one format to another. The cropping method IMHO most easily supports this analysis.

If I crop using the FF lenses and bodies available can I achieve the same desired outcomes as using a smaller format?

Do I get the resolution I need to do 300 pip prints in the desired size?
Do I have enough reserve resolution to crop further if I need to?
Do I get the size and weight I want?
Do I get the features for the cost I want?
Will I have the lens selection I want?

Direct link | Posted on Jul 11, 2014 at 18:33 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

kociasek: The caption under the photograph of the four lenses seems to be wrong. It says:
"These four lenses are all 85mm equivalent F1.2s. However, this does not mean they're all 85mm F1.2 equivalent."
Unless I'm mistaken, "equivalent" should be dropped from the first sentence.

Its funny that Richard also steadfastly refuses to acknowledge that crop sensors are called that for a reason. You crop and voila...equivalence.

No wizard or arcane equivalence calculations required.

Direct link | Posted on Jul 11, 2014 at 18:15 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Sven44: The penny has just dropped with me why a number of people still have a problem with this.

NO-ONE IS CLAIMING THAT THE F-RATIO GIVEN FOR SMALLER FORMAT CAMERAS IS WRONG.

No-one is claiming that f-ratios suddenly magically change when you switch formats (or crop and enlarge an image).

What we are doing is defining a NEW QUANTITY, which we claim is more useful than f-ratio, because it is comparable across formats.

We are calling this quantity the "Equivalent f-stop", but that's clearly got a lot of people's backs up and cause no end of confusion.

But what shall we call it then? The g-stop? "Normalised aperture" perhaps? I quite like that.

(Note, it is NOT the effective iris diameter, or f/N. That's a different thing again.)

@GB

"Is it also like a photo taken with the equivalent focal length, the equivalent f-ratio, the same shutter speed, and the equivalent ISO setting."

Except that you are inventing all these computations for no need at all and confusing people.

Otherwise there wouldn't be f2=f2=f2 discussions.

Don't use terms that ALREADY have specific uses to determine exposure. ESPECIALLY when a much simpler way of explaining equivalence exists.

Direct link | Posted on Jul 11, 2014 at 18:13 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

kociasek: The caption under the photograph of the four lenses seems to be wrong. It says:
"These four lenses are all 85mm equivalent F1.2s. However, this does not mean they're all 85mm F1.2 equivalent."
Unless I'm mistaken, "equivalent" should be dropped from the first sentence.

@GB

The 32mm f1.2 1/100 ISO 400 FF cropped to 85mm one you left out again and seem hell bent on always leaving out the simplest way to explain crop format equivalence.

Total light, DOF, diffraction, size, etc is identical. There is no need for any "equivalence" calculations.

Direct link | Posted on Jul 11, 2014 at 18:11 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

kociasek: The caption under the photograph of the four lenses seems to be wrong. It says:
"These four lenses are all 85mm equivalent F1.2s. However, this does not mean they're all 85mm F1.2 equivalent."
Unless I'm mistaken, "equivalent" should be dropped from the first sentence.

2 is accurate if you put cropped into the description (either mentally or in text):

87mm (crop) equivalent f1.2

or most clearly:

32mm f1.2 (87mm crop equivalent)

87mm f3.2 equivalent is NOT correct because exposure would be wrong if you tried to use it that way.

Direct link | Posted on Jul 11, 2014 at 17:17 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Sven44: The penny has just dropped with me why a number of people still have a problem with this.

NO-ONE IS CLAIMING THAT THE F-RATIO GIVEN FOR SMALLER FORMAT CAMERAS IS WRONG.

No-one is claiming that f-ratios suddenly magically change when you switch formats (or crop and enlarge an image).

What we are doing is defining a NEW QUANTITY, which we claim is more useful than f-ratio, because it is comparable across formats.

We are calling this quantity the "Equivalent f-stop", but that's clearly got a lot of people's backs up and cause no end of confusion.

But what shall we call it then? The g-stop? "Normalised aperture" perhaps? I quite like that.

(Note, it is NOT the effective iris diameter, or f/N. That's a different thing again.)

"What we are doing is defining a NEW QUANTITY, which we claim is more useful than f-ratio, because it is comparable across formats.

We are calling this quantity the "Equivalent f-stop", but that's clearly got a lot of people's backs up and cause no end of confusion."

Because you're inventing something that does not need to exist except for the reason you insist on doing your comparison in a convoluted way.

How do I compare across formats? What does 40mm on my crop camera mean in comparison to FF?

Simple:

Your crop image is like taking a 40mm shot in FF and CROPPING it to your crop factor. The DOF, FOV, f-number, ISO, shutter is all the same. No need to invent an "equivalent f-stop".

So when you are trying to figure out between FF and m43 all you need to do is determine if cropping FF gets you the size, weight, cost and resolution you want for the features you want vs a m43 offering.

Direct link | Posted on Jul 11, 2014 at 17:01 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Sven44: Proposition 1: All other things being equal, an image taken on a 2x crop camera with 40mm lens at f/1.4 1/125s ISO 200 will have the same framing, depth of field, brightness, even noise as one taken FF with 80mm at f/2.8 1/125s ISO 800.

Yes or no?

If not, then how do you explain the samples attached to this article? How do you explain away the equations governing magnification and DOF? You are on seriously weak ground here.

Yes? Then proceed:

Proposition 2: No other sets of values will yield similar results on the given formats.

Agree, yes or no?

No? Name them, and I'll show you how the results will differ.

Yes? Then,

Proposition 3: There are no other criteria of general importance to a photographer by which the above images could be distinguished.

Don't agree? Name them.

Yes? Then

Proposition 4: To all intents and purposes of importance to a photographer, the given sets of values are equivalent.

No? How exactly are you defining an equivalence relation?

Yes? We're done.

"Not done because we still need to resolve:
"f2=f2=f2, no if or buts" vs. "f2=f2=f2 is BS""

f2=f2=f2. Period. It's called "crop sensor" not "magically magnifying sensor".

When you approach it using the name of the sensor there is no mental gymnastics required. No need to compute "equivalent aperture" or even "equivalent DOF" and f2 remain f2 across formats.

Direct link | Posted on Jul 11, 2014 at 16:46 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Sven44: Proposition 1: All other things being equal, an image taken on a 2x crop camera with 40mm lens at f/1.4 1/125s ISO 200 will have the same framing, depth of field, brightness, even noise as one taken FF with 80mm at f/2.8 1/125s ISO 800.

Yes or no?

If not, then how do you explain the samples attached to this article? How do you explain away the equations governing magnification and DOF? You are on seriously weak ground here.

Yes? Then proceed:

Proposition 2: No other sets of values will yield similar results on the given formats.

Agree, yes or no?

No? Name them, and I'll show you how the results will differ.

Yes? Then,

Proposition 3: There are no other criteria of general importance to a photographer by which the above images could be distinguished.

Don't agree? Name them.

Yes? Then

Proposition 4: To all intents and purposes of importance to a photographer, the given sets of values are equivalent.

No? How exactly are you defining an equivalence relation?

Yes? We're done.

"What you don't seem prepared to do is proceed to calculating the impact of what you're doing."

And neither do you since you did not provide equivalence for 2.7 and 1.6 crop.

My representation is as accurate and FAR simpler to understand AND has the added benefit that it's part of the name: crop sensor.

What is the equivalence of a crop sensor and FF sensor?

You crop a FF image to the size of the crop sensor FOV and that's the equivalence when using the same focal length lens.

No need to compute "equivalent" aperture, DOF, f-stop, ISO or anything else. f2=f2=f2. 40mm=40mm. ISO 100=ISO 100.

MOST importantly it gives people the conceptual model to determine the benefits (or lack thereof) of using a crop format in terms of cost, size and IQ.

It becomes a fairly simple determination. Not some weird 4+ page treastie on total light equivalence and how to confuse people regarding how to do correct exposure (IE NOT with those equivalence values).

Direct link | Posted on Jul 11, 2014 at 16:35 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Sven44: Proposition 1: All other things being equal, an image taken on a 2x crop camera with 40mm lens at f/1.4 1/125s ISO 200 will have the same framing, depth of field, brightness, even noise as one taken FF with 80mm at f/2.8 1/125s ISO 800.

Yes or no?

If not, then how do you explain the samples attached to this article? How do you explain away the equations governing magnification and DOF? You are on seriously weak ground here.

Yes? Then proceed:

Proposition 2: No other sets of values will yield similar results on the given formats.

Agree, yes or no?

No? Name them, and I'll show you how the results will differ.

Yes? Then,

Proposition 3: There are no other criteria of general importance to a photographer by which the above images could be distinguished.

Don't agree? Name them.

Yes? Then

Proposition 4: To all intents and purposes of importance to a photographer, the given sets of values are equivalent.

No? How exactly are you defining an equivalence relation?

Yes? We're done.

"May I ask what the effect is of cropping and then magnifying your 40mm image to an 80mm FOV in the way you describe? Effect on DOF, that is? And noise?"

There's no difference in magnification between cropping a FF sensor and a crop sensor. No effect on DOF, framing, noise etc.

What is hard to understand?

"If you and your friend are photographing the same scene and he reaches for his 80mm lens, but you don't have one with you so resolve to crop and enlarge, any idea how your final image will compare to his?"

This is not a relevant comparison. The equivalence is between you with your crop camera and him with his FF camera both with a 40mm lens. Not between two FF cameras, one with a 40mm lens and one with an 80mm lens.

"You have not provided an alternative set of values, you have just restated my set of values with a (very slightly) different way of thinking about it."

A far more straightforward and better way. One which you seem to not get given your questions above.

Direct link | Posted on Jul 11, 2014 at 16:24 UTC
On What is equivalence and why should I care? article (2064 comments in total)
In reply to:

Sven44: Proposition 1: All other things being equal, an image taken on a 2x crop camera with 40mm lens at f/1.4 1/125s ISO 200 will have the same framing, depth of field, brightness, even noise as one taken FF with 80mm at f/2.8 1/125s ISO 800.

Yes or no?

If not, then how do you explain the samples attached to this article? How do you explain away the equations governing magnification and DOF? You are on seriously weak ground here.

Yes? Then proceed:

Proposition 2: No other sets of values will yield similar results on the given formats.

Agree, yes or no?

No? Name them, and I'll show you how the results will differ.

Yes? Then,

Proposition 3: There are no other criteria of general importance to a photographer by which the above images could be distinguished.

Don't agree? Name them.

Yes? Then

Proposition 4: To all intents and purposes of importance to a photographer, the given sets of values are equivalent.

No? How exactly are you defining an equivalence relation?

Yes? We're done.

P1: Yes.
P2. No.

An image taken on a 2x crop camera with 40mm lens at f/1.4 1/125s ISO 200 will have the same framing, depth of field, brightness, even noise as one taken FF with 40mm at f/1.8 1/125s ISO 200 CROPPED TO 80mm FOV.

There are, of course, nuances (resolution, sensor sensitivity, yada yada yada).

There are no mental hoops required to jump though to determine equivalence between crop and FF other than remembering it's a crop.

Using your way, quickly tell me the equivalence for a 2.7x crop in terms of focal length, f-stop and ISO. How about a 1.6x crop?

Direct link | Posted on Jul 11, 2014 at 15:10 UTC
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