Ming Thein about Oly E-M1.2 and equivalence

Started Nov 3, 2016 | Discussions
PerL Forum Pro • Posts: 14,083
Ming Thein about Oly E-M1.2 and equivalence
1

I read Ming Theins review of the new Olympus E-M1.2.

https://blog.mingthein.com/2016/11/02/review-olympus-e-m1-mark-ii/#more-13795

One interesting part was this:

"Let’s talk about the lenses for a moment: the 25/1.2 is impressive because of its performance and aperture; it’s tack sharp in the centre wide open, with the corners improving as you stop down a little .... However, it still has the depth of field transition properties of a real 25mm focal length, not 50; the whole idea of ‘equivalence’ to a 50/2.5 on FF is moot because the falloff in the transition zones isn’t what you’d expect it to be."

So, the depth of field transitions on equivalent lenses on different formats are different? That would an explanation why, say a 35 on APS-C doesn't quite feel the same as a 50 on FF.  (or a 25 mm on m43 or an 80 mm on MF, etc).

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SteveY80 Senior Member • Posts: 1,303
Re: Ming Thein about Oly E-M1.2 and equivalence
6

It would be interesting if someone could show some shots that demonstrate what he's talking about...

I've compared 25mm @ f/2 on M4/3 with 50mm f/4 on full frame and couldn't really see the difference in 'depth of field transition properties'. Lens properties obviously mean that there are some differences in rendering and bokeh, but as far as I can see that's not down to the focal length difference.

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OP PerL Forum Pro • Posts: 14,083
Re: Ming Thein about Oly E-M1.2 and equivalence
2

SteveY80 wrote:

It would be interesting if someone could show some shots that demonstrate what he's talking about...

Agree, it would be very interesting.

I've compared 25mm @ f/2 on M4/3 with 50mm f/4 on full frame and couldn't really see the difference in 'depth of field transition properties'. Lens properties obviously mean that there are some differences in rendering and bokeh, but as far as I can see that's not down to the focal length difference.

My experience is mostly 30 1.4 and 35 1.8 on APS-C vs 50 1.8 on FF. There is something that is hard to put a finger on. Another example is portraits or half figures shot with MF, that have a "look" that is hard to match.

Bob A L Senior Member • Posts: 2,215
Re: Ming Thein about Oly E-M1.2 and equivalence

Sometimes it pays to be stupid like me I suppose. For me ths is really easy to understand. If you go changing focal lengths, f stop and distance both to get the "equivalent" final results in the photo because of the sensor size, it's not going to be the same.  Close, but not the same. For us dummies, it's just as plain as can be. Put a 50mm lens set at f2 with subject at 10 feet from the camera and the resulting image as projected on the film plane is exactly the same no matter what size the sensor or film is. You just have more or less of it. DOF does not change.   How could it?

Boy, I'm in trouble now ain't I?

stevo23 Forum Pro • Posts: 23,326
Re: Ming Thein about Oly E-M1.2 and equivalence

PerL wrote:

I read Ming Theins review of the new Olympus E-M1.2.

https://blog.mingthein.com/2016/11/02/review-olympus-e-m1-mark-ii/#more-13795

One interesting part was this:

"Let’s talk about the lenses for a moment: the 25/1.2 is impressive because of its performance and aperture; it’s tack sharp in the centre wide open, with the corners improving as you stop down a little .... However, it still has the depth of field transition properties of a real 25mm focal length, not 50; the whole idea of ‘equivalence’ to a 50/2.5 on FF is moot because the falloff in the transition zones isn’t what you’d expect it to be."

So, the depth of field transitions on equivalent lenses on different formats are different? That would an explanation why, say a 35 on APS-C doesn't quite feel the same as a 50 on FF. (or a 25 mm on m43 or an 80 mm on MF, etc).

I think the DOF properties of that particular lens is what he is referring to, not 25mm M43 lenses in general. And as a generalization, equivalence in focal length and aperture isn't enough. The way the out of focus falls off, quickly or slowly or whatever, has to match.

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Glen Barrington
Glen Barrington Forum Pro • Posts: 20,422
Re: Ming Thein about Oly E-M1.2 and equivalence

I personally think this issue is muddied a bit by the whole "2X crop factor" of m43s.

It's probably a useful shorthand for the marketing types, and for quick 'good enough' field calculations, but anyone who has shot extensively with 4/3s and either FF or 135 film cameras knows that a 14 mm m43s lens does not carry the same emotional content of a 28 mm FF lens.

For the most part, they are very different lenses and so I usually take these sort of discussions with a certain amount of salt. It has been my experience that the 14 mm lens on m43s is a more intimate lens than a 28 mm FF lens. That 28 offers more breadth and scope than the 14. I think in FF one needs to go to 35 mm focal length to get the same level of . . . intimacy.

Because of this I think these human perceptions cloud our judgement when discussing things like edge softness differences and depth of focus. These things can be measured, of course, but how the lenses get used and our perceptions of effectiveness influences our value judgements of the lenses.  I suspect this perceptual difference is at the root of much of the arguments over 'equivalence'.

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stevo23 Forum Pro • Posts: 23,326
Re: Ming Thein about Oly E-M1.2 and equivalence

Glen Barrington wrote:

I personally think this issue is muddied a bit by the whole "2X crop factor" of m43s.

It's probably a useful shorthand for the marketing types, and for quick 'good enough' field calculations, but anyone who has shot extensively with 4/3s and either FF or 135 film cameras knows that a 14 mm m43s lens does not carry the same emotional content of a 28 mm FF lens.

For the most part, they are very different lenses and so I usually take these sort of discussions with a certain amount of salt. It has been my experience that the 14 mm lens on m43s is a more intimate lens than a 28 mm FF lens. That 28 offers more breadth and scope than the 14. I think in FF one needs to go to 35 mm focal length to get the same level of . . . intimacy.

Because of this I think these human perceptions cloud our judgement when discussing things like edge softness differences and depth of focus. These things can be measured, of course, but how the lenses get used and our perceptions of effectiveness influences our value judgements of the lenses. I suspect this perceptual difference is at the root of much of the arguments over 'equivalence'.

So how would we characterize lens intimacy? What characteristics do you think are at play to create this sense?

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SteveY80 Senior Member • Posts: 1,303
Re: Ming Thein about Oly E-M1.2 and equivalence

Bob A L wrote:

Sometimes it pays to be stupid like me I suppose. For me ths is really easy to understand. If you go changing focal lengths, f stop and distance both to get the "equivalent" final results in the photo because of the sensor size, it's not going to be the same. Close, but not the same.

For me the questions this raises are:

1. Why wouldn't it be the same?

2. What does the difference look like?

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Alphoid Veteran Member • Posts: 5,379
Re: Ming Thein about Oly E-M1.2 and equivalence
2

stevo23 wrote:

I think the DOF properties of that particular lens is what he is referring to, not 25mm M43 lenses in general. And as a generalization, equivalence in focal length and aperture isn't enough. The way the out of focus falls off, quickly or slowly or whatever, has to match.

The speed with which OOF falls off is identical.

Bokeh and similar may be different. But speed of falloff? Identical.

Alphoid Veteran Member • Posts: 5,379
Optical abberations
11

PerL wrote:

My experience is mostly 30 1.4 and 35 1.8 on APS-C vs 50 1.8 on FF. There is something that is hard to put a finger on. Another example is portraits or half figures shot with MF, that have a "look" that is hard to match.

A 50mm full frame f/2.8 lens and a 25mm MFT f/1.4 lens will have identical low-light, depth-of-field, OOF, diffraction, framing, and many other properties.

As a point of engineering, it's trivial to make an f/2.8 lens which is very sharp, has nice bokeh, and is otherwise optically terrific. It is hard to make an f/1.4 lens which is very sharp, let alone combining all of those properties. The full frame image is likely to be much sharper. Perhaps that's what you mean by the "hard" look? If you want tack-sharp and narrow depth-of-field, you really do need a reasonably large sensor.

Alphoid Veteran Member • Posts: 5,379
Re: Ming Thein about Oly E-M1.2 and equivalence

Bob A L wrote:

DOF does not change. How could it?

Let's say I have a lens which has sufficient DoF that I can just barely make out your arm -- the blur is about the same as the width of your arm.

  • If I take a photo of a crowd, your arm will be within the depth-of-field.
  • Now, let's say I do a tight crop on you. Your arm will be outside of the depth-of-field

That's why, generally, more magnification in an image leads to narrowed DoF and more out-of-focus blur. Macro photos tend to have -- quite literally -- razor-thin DoF. If I take a photo of a razor blade under a microscope, I can't get the whole thing in focus. Landscape, in contrast, has very wide depth-of-field.

Boy, I'm in trouble now ain't I?

Nope. Just missing that DoF is, fundamentally, a function of subject size. DoF calculations get really messy. There are a few useful rules-of-thumb, but once you move outside them, it's a bit of a disaster.

Dennis Forum Pro • Posts: 19,327
Re: Ming Thein about Oly E-M1.2 and equivalence

Glen Barrington wrote:

It's probably a useful shorthand for the marketing types, and for quick 'good enough' field calculations, but anyone who has shot extensively with 4/3s and either FF or 135 film cameras knows that a 14 mm m43s lens does not carry the same emotional content of a 28 mm FF lens.

I've never heard this before.

It has been my experience that the 14 mm lens on m43s is a more intimate lens than a 28 mm FF lens. That 28 offers more breadth and scope than the 14. I think in FF one needs to go to 35 mm focal length to get the same level of . . . intimacy.

I was going to suggest that it could be due to aspect ratio, but at 35.9mm (FF horizontal) versus 17.3mm (m43 horizontal) you're only looking at a 2.07X crop, so 14mm should have the same FOV as 29mm on FF. That's not nearly enough, I think, to explain whatever you're observing.

Leon Wittwer Forum Pro • Posts: 13,444
Re: Ming Thein about Oly E-M1.2 and equivalence
1

No, you are not in trouble.  You just don't understand DoF.  DoF is judged by looking at two approximately 8x10 images at about a foot.  Equivalence is how you get the "same" image regarding framing, perspective, DoF, diffraction, etc. in the magnified image to get from the sensor size to the 8x10 size.  It is the magnification where the sensor size impacts these image aspects.  Smaller sensors require larger magnification to get to the 8x10 size for comparison.  In the equations for DoF, the Circle of Confusion reflects the influence of the sensor size.  The CoC is proportional to the sensor size.

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Alphoid Veteran Member • Posts: 5,379
Well-established effect
6

Dennis wrote:

Glen Barrington wrote:

It's probably a useful shorthand for the marketing types, and for quick 'good enough' field calculations, but anyone who has shot extensively with 4/3s and either FF or 135 film cameras knows that a 14 mm m43s lens does not carry the same emotional content of a 28 mm FF lens.

I've never heard this before.

It's true. There is a well-known effect by which many of the rarer, larger sensor, and more niche brands result in photos with more emotional value.

Glen Barrington
Glen Barrington Forum Pro • Posts: 20,422
Re: Ming Thein about Oly E-M1.2 and equivalence

stevo23 wrote:

Glen Barrington wrote:

I personally think this issue is muddied a bit by the whole "2X crop factor" of m43s.

It's probably a useful shorthand for the marketing types, and for quick 'good enough' field calculations, but anyone who has shot extensively with 4/3s and either FF or 135 film cameras knows that a 14 mm m43s lens does not carry the same emotional content of a 28 mm FF lens.

For the most part, they are very different lenses and so I usually take these sort of discussions with a certain amount of salt. It has been my experience that the 14 mm lens on m43s is a more intimate lens than a 28 mm FF lens. That 28 offers more breadth and scope than the 14. I think in FF one needs to go to 35 mm focal length to get the same level of . . . intimacy.

Because of this I think these human perceptions cloud our judgement when discussing things like edge softness differences and depth of focus. These things can be measured, of course, but how the lenses get used and our perceptions of effectiveness influences our value judgements of the lenses. I suspect this perceptual difference is at the root of much of the arguments over 'equivalence'.

So how would we characterize lens intimacy? What characteristics do you think are at play to create this sense?

Good question! I know it when I see it! But how do we quantify it, or just set standards that say 'This is intimate', and 'This is not'. When we are talking about human perceptions, it is easy to get into the weeds and get lost in words. it really goes back to perceptions, and how our perceptions affect our attitudes about issues like equivalence.

Off the top of my head, I think the aspect ratio has a lot to do with it, and I don't think we can discount how the aspect ratio works with the focal length, to affect content and 'feel'. Then again, cropping can affect intimacy. You can crop to get more or less intimacy, but that really doesn't reflect the inherent level of intimacy that a given lens can deliver.

An "intimate" photo allows the user to focus on characteristics of the subject rather than seeing the subject as a whole. I think this is the key to perceived intimacy. Don't get me wrong, both have value, but they are different . . . results.

Also, it's not impossible to get sweep and scope with an m43s 14 mm lens, or intimacy with a FF 28 mm lens, it's just that I think they each lend themselves better to one than the other. I suspect our manipulation of intimacy factors in our photography is so common, that we don't fully realize we are doing it.

I don't think this is anywhere close to an adequate answer to your question, but I'm not sure a complete and 'universal' answer is possible.

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Glen Barrington
Glen Barrington Forum Pro • Posts: 20,422
The mistake in your logic . . .

Alphoid wrote:

Dennis wrote:

Glen Barrington wrote:

It's probably a useful shorthand for the marketing types, and for quick 'good enough' field calculations, but anyone who has shot extensively with 4/3s and either FF or 135 film cameras knows that a 14 mm m43s lens does not carry the same emotional content of a 28 mm FF lens.

I've never heard this before.

It's true. There is a well-known effect by which many of the rarer, larger sensor, and more niche brands result in photos with more emotional value.

is in the assumption that I place more value on one than the other, or that I'm pimping for one or the other. I'm not, I thought everyone just naturally saw what I saw. If you don't see it, then you don't see it, I guess.

But the truth is, I have to work harder in m43s to get those broad sweeping images than I do to get more intimate ones, and I think it affects not only my photography but in how I perceive technical issues in photography. (And the inverse was true when I was shooting 135 film)

Now the extra level of work is not great, and as I said in a different post, we ALL do this intimacy/sweep manipulation so much, and it is such a part of our 'workflow' that we don't even notice it. But it is there, and I don't think we can fully discount how it affects our perceptions of the world, at least in a photographic sense.

There is more to the equivalence issue than just a quantifiable technical factor.

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Alphoid Veteran Member • Posts: 5,379
Clarification of my logic
4

I don't disagree with anything you said. I disagree with why. Emotion is just that -- emotion. It is driven by the state-of-mind of the photographer. There's a difference to the feel of shooting with a $5000 camera to a $50 camera, in both directions, and they make for very different types of photos. There's a difference between a camera which feels like an extension of the arm, like a gizmo, or like a scientific instrument. There's a difference if using a camera is fun, a chore, or major endevor. They'll result in different photos.

We run into very significant issues. Placebo effect. Cognitive bias. Stereotype bias. These are not small impacts. If you believe a camera is better at landscape, you will take significantly better landscape photos with it. If you believe it's worse at portraiture, you'll take significantly worse portraits.

All of those cameras might produce technically identical images, in the sense that if you set them on a tripod, point them in the same direction, and set them to the same shutter, equivalent ISO, and equivalent aperture, the photos might be indistinguishable. But that's not how people will use them in the field.

I read an article from a photographer who used a viewfinder camera principally because the process of setting it up and preparing everything resulted in the right state of mind. Each photo became an undertaking.

That's all okay, and much more important than whether a given piece of equipment rates 20% higher or lower on DxOMark. But it's also personal. Some people will find MFT better for personal. Others will prefer an RX100. Others a cell phone. Others a medium format. Others a view camera with 4x5 film.

Dennis Forum Pro • Posts: 19,327
Re: Clarification of my logic

Alphoid wrote:

I don't disagree with anything you said. I disagree with why. Emotion is just that -- emotion. It is driven by the state-of-mind of the photographer. There's a difference to the feel of shooting with a $5000 camera to a $50 camera, in both directions, and they make for very different types of photos.

I guess the test would be to shoot FF with 28mm, m43 with 14mm, and then show the results to someone who doesn't know what they were shot with. I'd be curious, because Glen's observation doesn't sound intuitive to me.

stevo23 Forum Pro • Posts: 23,326
Re: Ming Thein about Oly E-M1.2 and equivalence

Alphoid wrote:

stevo23 wrote:

I think the DOF properties of that particular lens is what he is referring to, not 25mm M43 lenses in general. And as a generalization, equivalence in focal length and aperture isn't enough. The way the out of focus falls off, quickly or slowly or whatever, has to match.

The speed with which OOF falls off is identical.

Between what and what?

Bokeh and similar may be different. But speed of falloff? Identical.

A good place to see how this can be different from one lens to the next, look at Voigtlander who have certain "classic" designs that essentially drop quickly as opposed to the more modern designs that have a more gradual focus drop.

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stevo23 Forum Pro • Posts: 23,326
Re: Ming Thein about Oly E-M1.2 and equivalence

Glen Barrington wrote:

stevo23 wrote:

Glen Barrington wrote:

I personally think this issue is muddied a bit by the whole "2X crop factor" of m43s.

It's probably a useful shorthand for the marketing types, and for quick 'good enough' field calculations, but anyone who has shot extensively with 4/3s and either FF or 135 film cameras knows that a 14 mm m43s lens does not carry the same emotional content of a 28 mm FF lens.

For the most part, they are very different lenses and so I usually take these sort of discussions with a certain amount of salt. It has been my experience that the 14 mm lens on m43s is a more intimate lens than a 28 mm FF lens. That 28 offers more breadth and scope than the 14. I think in FF one needs to go to 35 mm focal length to get the same level of . . . intimacy.

Because of this I think these human perceptions cloud our judgement when discussing things like edge softness differences and depth of focus. These things can be measured, of course, but how the lenses get used and our perceptions of effectiveness influences our value judgements of the lenses. I suspect this perceptual difference is at the root of much of the arguments over 'equivalence'.

So how would we characterize lens intimacy? What characteristics do you think are at play to create this sense?

Good question! I know it when I see it! But how do we quantify it, or just set standards that say 'This is intimate', and 'This is not'. When we are talking about human perceptions, it is easy to get into the weeds and get lost in words. it really goes back to perceptions, and how our perceptions affect our attitudes about issues like equivalence.

Off the top of my head, I think the aspect ratio has a lot to do with it, and I don't think we can discount how the aspect ratio works with the focal length, to affect content and 'feel'. Then again, cropping can affect intimacy. You can crop to get more or less intimacy, but that really doesn't reflect the inherent level of intimacy that a given lens can deliver.

An "intimate" photo allows the user to focus on characteristics of the subject rather than seeing the subject as a whole. I think this is the key to perceived intimacy. Don't get me wrong, both have value, but they are different . . . results.

Also, it's not impossible to get sweep and scope with an m43s 14 mm lens, or intimacy with a FF 28 mm lens, it's just that I think they each lend themselves better to one than the other. I suspect our manipulation of intimacy factors in our photography is so common, that we don't fully realize we are doing it.

I don't think this is anywhere close to an adequate answer to your question, but I'm not sure a complete and 'universal' answer is possible.

But worth exploring I think. I also wonder if there isn't a lot of variation from one lens design to the next. Voigtlander makes a few 35mm and 50mm lenses, each touted as having a different "character" with some of that character being related to the quickness with which focus drops off into the out of focus regions.

Just a thought.

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