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Archive 2013 · Yesterday's medium format digital backs
  
 
RustyBug
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p.2 #1 · p.2 #1 · Yesterday's medium format digital backs


So how does using FF lens on a smaller format "ruin" it?

I mean, if I've got a Canon 135/2 and mount it on a 5D, 1D II and a Rebel ... how does using any of these different sensor size cameras get ruined by using full frame glass? The projected image from the lens will be the EXACT SAME, they will simply be capturing a different cropped portion of the projected image circle.

Imo, this is no different than projecting an image from an enlarger to cover an 8x10 sheet of paper, then replacing the 8x10 area of capture with a 5x7 sheet of paper. The projected image will be EXACTLY the same, only the area of cropped capture will be different.

The main reason for using MF glass on FF is two-fold, less vignetting, smoother transitions. If you like the higher contrast afforded by platforms with smaller sensors and their glass designed to produce a smaller image circle and its corresponding projection differences, then you may not appreciate the large image circle projection from the larger platforms.

Another way to consider it is to compare Leica M vs. Leica R ... load a roll of the same film (same capture area/grain structure) into each and yet you get different "looks". What properties are involved that yield the variance? Imo, it isn't the different format of the capture, it is the properties of the projected image that render the difference. So it is with choosing to use MF glass ... it offers a different image projection, even if you are only capturing a cropped portion of what it might provide with its larger image circle (a product of being farther from the image plane).

However, that projected image is the EXACT same projection whether you mount it to an MF, FF, APS-H, APS-C or 4/3 camera. The only thing that changes, is the area captured/recorded of that projection. The projected image never changes. If you like the drawing style of the projection from MF glass ... it hasn't changed, no matter what you project it onto.

If you mount MF glass on a camera with a MF sensor size of 44x33, does it give you the MF look at the 33mm edge? If the projected image @ 33mm renders the MF "look", then why wouldn't a projection capture @ 36mm edge of FF render the "look" ... isn't it the same projection?



Edited on Jul 01, 2013 at 02:22 PM · View previous versions



Jul 01, 2013 at 02:10 PM
naturephoto1
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p.2 #2 · p.2 #2 · Yesterday's medium format digital backs


RustyBug wrote:
So how does using FF lens on a smaller format "ruin" it?

I mean, if I've got a Canon 135/2 and mount it on a 5D, 1D II and a Rebel ... how does using any of these different sensor size cameras get ruined by using full frame glass? The projected image from the lens will be the EXACT SAME, they will simply be capturing a different cropped portion of the projected image circle.

Imo, this is no different than projecting an image from an enlarger to cover an 8x10 sheet of paper, then replacing the 8x10 area of capture with
...Show more

I doubt that there would be much if any smoother transition by using a MF lens on a FF sensor though there may be some if you did sufficient stitching of imagaes. The FF lenses will generally be sharper than the MF lenses (unless we are now talking about some of the very expensive new MF digital lenses like those by Rodenstock and Schneider). The MF lens on the FF sensor/camera however, would afford the opportunity of using shifts and tilts to cover the FF sensor. That is the same as using LF lenses with LF cameras or FF lenses on APS-C sensors. The smoother transition would be observed when using the MF lenses on MF film or sensor however due to the size as it is when using LF lenses on LF film or MF sensors.

Rich



Jul 01, 2013 at 02:22 PM
RustyBug
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p.2 #3 · p.2 #3 · Yesterday's medium format digital backs


All I'm saying is ... the projected image of a given piece of glass remains the same, regardless of what you mount it too. If you like the projected image from the Voigt 125 or Leica 100 APO ... mounting them on a crop body doesn't "ruin" anything. Neither does mounting MF glass on FF or crop.


Jul 01, 2013 at 02:58 PM
mawz
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p.2 #4 · p.2 #4 · Yesterday's medium format digital backs


An 80 on a typical crop MFDB will be about equivalent to a 65 on 35mm FF ((80x1.3)/1.6). On the 645D, which has the typical 44x33mm sensor a 55mm is normal (vice a ~43mm on FF and a 70 on 645), crop factor is around 1.3x to 645 for most sensors. A 35mm FF sensor has a crop factor of 1.6x for reference.


Jul 01, 2013 at 03:25 PM
Johnny B Goode
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p.2 #5 · p.2 #5 · Yesterday's medium format digital backs


RustyBug wrote:
All I'm saying is ... the projected image of a given piece of glass remains the same, regardless of what you mount it too. If you like the projected image from the Voigt 125 or Leica 100 APO ... mounting them on a crop body doesn't "ruin" anything. Neither does mounting MF glass on FF or crop.



True but it increases your distance to the subject to obtain the same frame of view. Increased distance to your subject increases your depth of field.



Jul 01, 2013 at 04:33 PM
RustyBug
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p.2 #6 · p.2 #6 · Yesterday's medium format digital backs


If you are trying to garner an equivalent FOV between formats ... but if you are only considering the FF format that you are working in, your FOV will be the same whether you are using FF glass or MF glass, i.e. 80mm = 80mm and your subject distance will remain the same.

If you compared the M645 200/2.8 APO on a 5D vs. the Canon 200/2.8L on a 5D ... your fov and subject distance would be the same. However, the fact that the distance from the exit pupil to the film plane is longer in the case of the MF glass, the transitions can be smoother as the light path fans out more over the longer distance to the film plane (other optical design variables notwithstanding). The increase in distance to the film plane is responsible for both the larger image circle and and the difference in transitions at the film plane. Additionally, the MF glass has a larger physical aperture (for a similar f-stop number) as the f-stop calculation is rooted on the basis of the relationship to its native format size, not its actual aperture size.

OEM designed crop glass harnesses this principle inversely as the shorter distance to the film plane yields more rapid transitions. Same applies for the diff @ Leica M vs. Leica R even though the capture area is the same size. Similar applies for Adapt-all glass and FF format TS glass where the exit pupil is farther from the film plane than "normal" FF glass. The longer the distance from the exit pupil to the capture area, the smoother the transitions will be. This is largely why people suggest that MF glass isn't "as sharp" as FF glass and why some really contrasty glass extends closer to the film plane (for a given FL).

Thus, if you like the MF look of a piece of MF glass, you can shoot it on anything, just that you'll have a smaller capture area. Most people get hung up on the look of MF being due to the extra real estate of the format. It is due to the distance from the film plane that the projection travels as it fans out more.

If you were to shoot a head shot of a person with a given MF lens of choice on MF format, but you shot it in landscape orientation, only to realize you would prefer it in portrait orientation. So, you crop off the sides .. will the MF "look" change because you cropped off the sides and only used the "central" portion of the capture areas? How then is the quality of the projection changed by only capturing the "central" portion on the FF format?


Anyway, not likely that I'll make a believer out of those who have never shot MF on FF ... and not really trying to. I'm just sharing for the benefit of consideration, if it should make some sense to your needs/goals/application. My research into the possibility of getting an older MF back, led me to pass on the back ... but say yes to the glass.





Jul 01, 2013 at 04:53 PM
Johnny B Goode
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p.2 #7 · p.2 #7 · Yesterday's medium format digital backs


RustyBug wrote:
If you compared the M645 200/2.8 APO on a 5D vs. the Canon 200/2.8L on a 5D ... your fov and subject distance would be the same. However, the fact that the distance from the exit pupil to the film plane is longer in the case of the MF glass, the transitions can be smoother as the light path fans out more over the longer distance to the film plane (other optical design variables notwithstanding). The increase in distance to the film plane is responsible for both the larger image circle and and the difference in transitions at the film
...Show more

Had not thought about that. Thank you for the insight.



Jul 01, 2013 at 06:54 PM
alundeb
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p.2 #8 · p.2 #8 · Yesterday's medium format digital backs


Johnny B Goode wrote:
Had not thought about that. Thank you for the insight.


Yes, the exit pupil distance is important in digital.

The last sentence is wrong though. The f-number is simply the ratio between the focal length and the aperture diameter regardless the native format size.



Jul 01, 2013 at 06:58 PM
RustyBug
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p.2 #9 · p.2 #9 · Yesterday's medium format digital backs


Yes, the F-stop is a ratio between the aperture diameter and the focal length ... consistent with a given format. Nobody ever expected people to be using "oversized" format glass on smaller format cameras, so the reference to format size as part of the calculation is essentially dropped, and common knowledge only mentions the ratio to FL, without mention of the format size but it does exist as part of the actual calculation, iirc.

I realize I'll get "stoned" for the blasphemy of suggesting such, so I'll try and find the calculations that incorporate the area. It was a few years back when I found it and unfortunately didn't save it.

In the mean time ... for a given focal length @ say 8X10 format vs. the same focal length @ 4/3 format (i.e. arbitrarily both @ 100mm) would the physical aperture of f32 be the same size in each lens?

This isn't the reference I was looking for (there's a much better one), but as a primer ...

https://en.wikipedia.org/wiki/Aperture
Where f is focal length and N is the f-number.










Jul 01, 2013 at 09:56 PM
Makten
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p.2 #10 · p.2 #10 · Yesterday's medium format digital backs


RustyBug wrote:
So how does using FF lens on a smaller format "ruin" it?

I mean, if I've got a Canon 135/2 and mount it on a 5D, 1D II and a Rebel ... how does using any of these different sensor size cameras get ruined by using full frame glass? The projected image from the lens will be the EXACT SAME, they will simply be capturing a different cropped portion of the projected image circle.


Well, you crop out half the image area and get something else than you'd (I'd) expect from the lens. You then have a larger magnification of aberrations and a narrower angle of view.

The main reason for using MF glass on FF is two-fold, less vignetting, smoother transitions.

I'd really like to see those "smoother transitions". Really.

However, that projected image is the EXACT same projection whether you mount it to an MF, FF, APS-H, APS-C or 4/3 camera.

Yeah, which makes most FF lenses (unless reach is what you want) less good on APS-C.

If you mount MF glass on a camera with a MF sensor size of 44x33, does it give you the MF look at the 33mm edge?

Of course not, since you are getting a narrower angle of view. The "MF look" is to me about short DOF, z low amount of aberrations and high local contrast at a certain angle of view. Crop it, and the look is gone.

The "MF look" is not a property of the lens, but of the image format. How about trying to get this result from a smallish sensor. Good luck, since you'd need a ~50/1.2 on FF that is sharper wide open than any FF 50 mm lens is stopped down.


The end by Martin Hertsius, on Flickr



Edited on Jul 01, 2013 at 10:36 PM · View previous versions



Jul 01, 2013 at 10:31 PM
 

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Taylor Sherman
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p.2 #11 · p.2 #11 · Yesterday's medium format digital backs


RustyBug wrote:
If you compared the M645 200/2.8 APO on a 5D vs. the Canon 200/2.8L on a 5D ... your fov and subject distance would be the same. However, the fact that the distance from the exit pupil to the film plane is longer in the case of the MF glass, the transitions can be smoother as the light path fans out more over the longer distance to the film plane (other optical design variables notwithstanding). The increase in distance to the film plane is responsible for both the larger image circle and and the difference in transitions at the film
...Show more

Physical aperture? maybe, I don't know enough to say.

Optical aperture (pupil diameter)? they will be identical - each one will appear to be 71.428mm in diameter when looking at the front of the lens. And this, plus subject distance, is what determines DOF.

Are you trying to say that the actual physical aperture size, regardless of the optical aperture, makes a difference in rendering independent of other lens differences?




Jul 01, 2013 at 10:33 PM
Makten
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p.2 #12 · p.2 #12 · Yesterday's medium format digital backs


RustyBug wrote:
If you compared the M645 200/2.8 APO on a 5D vs. the Canon 200/2.8L on a 5D ... your fov and subject distance would be the same. However, the fact that the distance from the exit pupil to the film plane is longer in the case of the MF glass, the transitions can be smoother as the light path fans out more over the longer distance to the film plane (other optical design variables notwithstanding). The increase in distance to the film plane is responsible for both the larger image circle and and the difference in transitions at the film
...Show more

Sorry (and I don't intend to be rude), but you obviously don't have a clue of what you're talking about.



Jul 01, 2013 at 10:40 PM
douglasf13
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p.2 #13 · p.2 #13 · Yesterday's medium format digital backs


F-stops are simply the focal length divided by the diameter of the entrance pupil. Format size is not part of the equation, RustyBug.


Jul 01, 2013 at 10:41 PM
RustyBug
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p.2 #14 · p.2 #14 · Yesterday's medium format digital backs


Did this crop "ruin" the look?








Edited on Jul 01, 2013 at 10:46 PM · View previous versions



Jul 01, 2013 at 10:43 PM
Makten
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p.2 #15 · p.2 #15 · Yesterday's medium format digital backs


RustyBug wrote:
Did this crop "ruin" the look.


Of course it did. It's not the image I intended to shoot.

Edit: Now, this was shot on 6x7 so no matter what digital equipemt you'd buy, there is no alternative. But think one step further. If you'd want the same AOV as in the original shot, with a smaller film or sensor area, you would have to use a shorter focal length. And then that lens would have to be faster (same entrance pupil), and be sharper.


Edited on Jul 01, 2013 at 10:50 PM · View previous versions



Jul 01, 2013 at 10:45 PM
douglasf13
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p.2 #16 · p.2 #16 · Yesterday's medium format digital backs


Of course, the entrance pupil itself is just an image of the aperture, not the actual aperture size itself.


Jul 01, 2013 at 10:46 PM
RustyBug
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p.2 #17 · p.2 #17 · Yesterday's medium format digital backs


The context has been that of using MF glass of the same focal length as it's smaller format counterpart. 80mm Canon vs. 80mm MF would have captured the same FOV on FF regardless of which lens you chose to use.

Granted that the crop here changed the FOV, but I'm not talking about switching from a larger format body to a smaller format body. I'm talking about using a larger format lens of the same focal length as you would have chosen from your FF glass. It will render differently ... it will render in accord with its projection.

You're missing the point ... you're thinking that I'm suggesting using a smaller format capture area is going to be the same as what you can achieve with a larger format system. That's not what I'm saying. What I'm saying is that their are two parts to the equation ... the projection and the capture area. Even if you don't increase your capture area associated with the larger format, you can still harness the optics of the larger format glass ... albeit a smaller fov than if you were to capture the entire projection on the larger format. The drawing style of the projected image remains the same, cropped or not. If you like the drawing style it gives you for "the look", you can still get "the look" ... at least a portion of it.

Edited on Jul 01, 2013 at 10:58 PM · View previous versions



Jul 01, 2013 at 10:56 PM
douglasf13
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p.2 #18 · p.2 #18 · Yesterday's medium format digital backs


I think I may be confused overall as to what you're saying.


Jul 01, 2013 at 10:58 PM
RustyBug
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p.2 #19 · p.2 #19 · Yesterday's medium format digital backs


I'm saying ... the drawing style / quality of the projected image remains the same regardless of whether you capture the whole thing, or only a portion of it. If you like the drawing style / quality that MF glass projects, use it on FF and capture those inherent qualities of the MF glass.

I'm not trying to establish equivalency @ FOV between two different platforms, I'm saying that an MF 80mm lens will render more like MF than an 80mm FF lens ... because it is an MF lens.



Edited on Jul 01, 2013 at 11:05 PM · View previous versions



Jul 01, 2013 at 11:02 PM
Makten
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p.2 #20 · p.2 #20 · Yesterday's medium format digital backs


RustyBug wrote:
Granted that the crop here changed the FOV, but I'm not talking about switching from a larger format body to a smaller format body. I'm talking about using a larger format lens of the same focal length as you would have chosen from your FF glass. It will render differently ... it will render in accord with its projection.


Of course, and the MF lens will most likey render a less sharp image on FF than an FF lens with the same focal length. There is no inbuilt mojo in MF lenses. They project a larger image circle and thus in most cases give lower resolution.

I suggest you try it out for yourself. If I had a P67 adapter I'd compare the 105/2.4 to the Nikkor 105/2.5, and I'm sure the Nikkor would perform better because of the smaller image circle.



Jul 01, 2013 at 11:03 PM
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