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07-20-2015, 02:45 AM - 1 Like   #106
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Equivalence is only useful if you shoot multiple formats and can't figure out which lenses to use for what purposes on a given format or, if you want to prove to folks that use four thirds, APS-C or digital medium format that 35mm digital is better.

07-20-2015, 04:57 AM   #107
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QuoteOriginally posted by kh1234567890 Quote
I must be a bit slow in my old age - I thought that 'equivalence' meant that you could get exactly the same shot on different sensor/film formats. Including perspective. Obviously I was wrong.
Equivalence, in the context of these discussions, often means whatever the person making the post wants it to mean.
QuoteOriginally posted by kh1234567890 Quote
So, 'equivalence' is a pretty pointless concept in practice.
By Jove, I think you've got it!
07-20-2015, 05:00 AM   #108
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I regularly use equivalence in a practical way. For example I was on DXOMark and noticed they've posted a "best zooms" list for the D750. In order to understand what the zooms were capable of, I needed to translate to my reference, which is APS-C. A 24-120mm f3.5-5.6 on FF doesn't mean much to me until I turn it into 16-80mm f2.3-3.7. Now I know exactly what it's operating parameters are.

---------- Post added 2015-07-20 at 08:03 ----------

QuoteOriginally posted by kh1234567890 Quote
So, 'equivalence' is a pretty pointless concept in practice.
I thought what Jay suggested, i.e. using an APS-C setup to see how an image would look on FF, was pretty clever.
07-20-2015, 09:26 AM   #109
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Here's another area where equivalence theory helps out. When shooting people on a stage, (it can be a political rally, a graduation ceremony, or an acting stage - whatever) its important to have enough DOF to encompass, as a minimum, both heads of a "conversation". There are useful APP calculators built into smart phones and similar devices, that one can calculate in advance what the camera aperture should be set at for your distance to the stage. I calculate a coupla situations in advance and write the settings on cards so i know where to start from. Saves a lot of wasted shooting.

07-20-2015, 05:12 PM - 1 Like   #110
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QuoteOriginally posted by kh1234567890 Quote
So, 'equivalence' is a pretty pointless concept in practice.
Not at all, not by a long shot. It just doesn't usually seem to matter much to a % of folks who only intend to shoot one format. If you're looking to change formats for some reason, or add a format (bigger or smaller), it's certainly in your best interest to know about it.

Of course, no-one's forcing you to care about it at all, or to care about anything technically-related to your hobby or profession if you don't want to. I don't get that attitude, but TEHO I guess.

---------- Post added 07-20-15 at 06:20 PM ----------

QuoteOriginally posted by Parallax Quote
Equivalence, in the context of these discussions, often means whatever the person making the post wants it to mean.By Jove, I think you've got it!
Translation: Parallax gets bored with all that techie stuff! Just go out and shoot durg-gurn it!

Oh, and here you go, I know you'll love this: Joseph James tries his very best to help Parallax

Last edited by jsherman999; 07-20-2015 at 05:23 PM.
07-20-2015, 06:14 PM   #111
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QuoteOriginally posted by jsherman999 Quote

Translation: Parallax gets bored with all that techie stuff! Just go out and shoot durg-gurn it!

Oh, and here you go, I know you'll love this: Joseph James tries his very best to help Parallax
07-21-2015, 10:02 PM - 1 Like   #112
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QuoteOriginally posted by Rondec Quote
Equivalence is only useful if you shoot multiple formats and can't figure out which lenses to use for what purposes on a given format or, if you want to prove to folks that use four thirds, APS-C or digital medium format that 35mm digital is better.
Equivalence plays out all the time when individuals use only one format and they didnít really know it
Anytime someone used a 1.4 tc or 2.0 tc or cropping within a format is there the big E
If we use a 1.4 tc on a 200mm F2.8 lens the final image will have the appearance of a 280mm F/4 lens, the same way if one was to crop that 200mm F/2.8 lens to the same FOV as the 1.4 tc image you will wind up with an image with very similar in FOV and DOF and total light ( noise) there is the big E again.
07-22-2015, 02:32 AM   #113
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QuoteOriginally posted by Ian Stuart Forsyth Quote
Equivalence plays out all the time when individuals use only one format and they didnít really know it
Anytime someone used a 1.4 tc or 2.0 tc or cropping within a format is there the big E
If we use a 1.4 tc on a 200mm F2.8 lens the final image will have the appearance of a 280mm F/4 lens, the same way if one was to crop that 200mm F/2.8 lens to the same FOV as the 1.4 tc image you will wind up with an image with very similar in FOV and DOF and total light ( noise) there is the big E again.
That's fine. I don't think many people use TCs and those who do probably know what kind of framing and light capability they have with their TC combined with their 200 f2.8 or 300 f4 lenses without resorting to some formula. I certainly don't think, every time I mount my FA 31 limited that it is a 50mm f2.8 equivalent lens on full frame. For one thing, that doesn't mean much to me, for another, I am seldom shooting at f1.8.

In the end, I find equivalence is mainly brought out by full frame proponents to say why fast lenses on crop cameras aren't really fast and why full frame is better. Folks who shoot APS-C exclusively don't seem to bring out the whole equivalence thing much. It came out in a thread recently about the 200 f2.8, where the point was made that it was the same as a 300mm f4 on full frame (not sure why, the thread was about how prices were going down on the 200mm lens) and in a 50-135 f2.8 discussion to explain how it really wasn't that great because it was only a 70-200 f4 equivalent lens. It just is weird that it has to be trotted out in all sorts of threads that have nothing to do with full frame cameras or lenses.

07-22-2015, 04:30 AM - 2 Likes   #114
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QuoteOriginally posted by Rondec Quote
It just is weird that it has to be trotted out in all sorts of threads that have nothing to do with full frame cameras or lenses.
I think the argument mainly started because m4/3 shooters don't understand the full ramifications of crop factor. They only understand equivalent focal length. They think the Olympus 12-40mm f2.8 is a 24-80mm f2.8 FF equivalent, when in reality it is a 24-80mm f5.6 equivalent.

It got really heated over at DPR when the Olympus 300mm f4 was announced, and there were several threads showing photos of it beside a huge Canon 600mm f4 FF lens, with price comparisons.

The Oly 300mm f4 is no smaller than a Pentax DA*300. If you shoot them with an EM-1 and K-3, and crop the Pentax image to 16mp and 4:3 aspect ratio, you will have the same image. That is equivalence. Comparing to a 600mm f4 is just ignorance.

Last edited by audiobomber; 07-22-2015 at 04:41 AM.
07-22-2015, 06:52 AM   #115
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the simple answer to this question about depth of field that everyone likes to complicate moan bitch and start wars over is....

the closer you are to the subject you want in focus, the narrower your depth of field is gonna be

and the easiest way to stop all this f-stop confusion when it comes to camera's with sensors smaller than full frame is to publish the both f-stop and focal length in 35mm equivalent (something i wish would happen but camera manufactures will never do)

another rating i wish for is T-stops (TRUE LENS SPEED)

example - Canon 85mm f1.2L is T1.4, the Sigma 35mm f1.4 is T1.4, Konica Minolta AF 50mm f/1.4 whopping T2.0 hell the Sigma 18-35mm F1.8 is faster T1.9
07-22-2015, 06:56 AM   #116
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QuoteOriginally posted by audiobomber Quote
I think the argument mainly started because m4/3 shooters don't understand the full ramifications of crop factor. They only understand equivalent focal length. They think the Olympus 12-40mm f2.8 is a 24-80mm f2.8 FF equivalent, when in reality it is a 24-80mm f5.6 equivalent.

It got really heated over at DPR when the Olympus 300mm f4 was announced, and there were several threads showing photos of it beside a huge Canon 600mm f4 FF lens, with price comparisons.

The Oly 300mm f4 is no smaller than a Pentax DA*300. If you shoot them with an EM-1 and K-3, and crop the Pentax image to 16mp and 4:3 aspect ratio, you will have the same image. That is equivalence. Comparing to a 600mm f4 is just ignorance.
I hope at this point people understand that a 300mm lens is the same whatever format you shoot it on. Smaller formats only give more "length" to lenses if they are more pixel dense. But even that gives diminishing returns. From what I have seen of telephoto on the Q shots, the quality begins to suffer, even though there is technically a lot of reach there.

If I post something about my FA 77, I am unlikely to say that it is a 115mm equivalent, because that doesn't mean anything to me. I just like the fact that it has nice rendering and is capable of pretty shallow depth of field. Whether or not it would be better on full frame is meaningless to me. But if I would start a thread about it, there would be folks who would show up to tell how because of the crop factor, it isn't a useful lens, it would be better on full frame, etc.

It just gets a little old. It was a fine lens on film, it is a fine lens on a K3, and it will continue to be a fine lens when the new full frame Pentax comes out. But the comparisons do nothing for me.
07-22-2015, 07:18 AM - 1 Like   #117
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QuoteOriginally posted by Rondec Quote
Folks who shoot APS-C exclusively don't seem to bring out the whole equivalence thing much.
Many APS-C folks do exactly that while putting down m4/3 gear. Not that many of them use the word equivalence*. But the very ideas embodied in equivalence are often used to prove APS-C is "better" than m4/3. And were you hiding under a rock when the Q came out? The vitriol directed at that camera, by APS-C users in large part, was incredible. And many of the arguments were based in equivalence concepts. All miss-uses of the concept, in my view. Equivalence does not imbue a "better than" attribute on one format vs. another. It can provide useful information to make rational choice of one vs. another for a specific purpose. People are just so self-centered that they believe their "specific purpose" is or ought to be everyone's.

*It's such a misunderstood concept and so the word has become encumbered with all sorts of false meaning and emotional baggage. But many defend their choice of gear using the very ideas behind equivalence, yet will say in the same breath that equivalence is invalid.
07-22-2015, 07:20 AM - 1 Like   #118
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QuoteOriginally posted by audiobomber Quote
The Oly 300mm f4 is no smaller than a Pentax DA*300. If you shoot them with an EM-1 and K-3, and crop the Pentax image to 16mp and 4:3 aspect ratio, you will have the same image. That is equivalence. Comparing to a 600mm f4 is just ignorance.
Dan, thanks, this statement is exactly what I am looking for.. and also my understanding.

To reference a parallel example, I use a 31mm f1.8 on a (future) Pentax FF with similar pixel density (assumption) as k-3. The resulting image cropped to APS-C size as if it is taken from the k-3, both images should be identical if both taken from the same distance from subject. Although the exposure could be slightly different due to metering of a bigger/smaller scene from the two cameras. DOF remains the same since subject distances are the same (?), though I am not sure.
07-22-2015, 07:26 AM   #119
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In RE OP's Question..

In regard to the original question: NOPE!
07-22-2015, 07:33 AM   #120
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QuoteOriginally posted by aleonx3 Quote
DOF remains the same since subject distances are the same (?), though I am not sure.
As long as you crop the FF image to the same extent as the APS-C image then of course it will look the same (any differences in sensor resolution, sensitivity, noise etc. excepted).
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