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Archive 2013 · Yesterday's medium format digital backs
  
 
FredBGG
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p.7 #1 · p.7 #1 · Yesterday's medium format digital backs


An "full frame" 6x8cm MF lens compared to a Nikon lens.

Nikon 85mm 1.4G compared to the Fuji GX680 65mm (big heavy design with few design constraints)

The Fuji is just a wee bit sharper than the already very good Nikon 85mm 1.4G. Both were shot at F11.

Using the whole image area of the Fuji that covers over 80x80mm results in really high quality.



Even with film the Fuji gx680 lenses produce very sharp and nice detail while having a look that is that of full fledged medium format, not what I call crop frame MFD of 33x44mm 40 MP sensors.

Here is an example of shapness Fuji gx680 180mm wide open at f 3.2 Phase One p25+ with some lens tilt
100% magnification.



Fuji gx680 250mm Plus-x-pan 125



Crop






Jul 05, 2013 at 04:59 AM
alundeb
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p.7 #2 · p.7 #2 · Yesterday's medium format digital backs


What was the recording medium in the test chart comparison above?
What magnification / enlargement are we looking at?
It is probably not 100% crops from a digital Bayer sensor.

The Fujinon sure looks like a superb lens.



Jul 05, 2013 at 05:50 AM
carstenw
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p.7 #3 · p.7 #3 · Yesterday's medium format digital backs


Makten wrote:
Why would colors be different because of a larger image circle? And what is the "tonality" you are talking about?


Some of this is due to the more relaxed designs of the medium format lenses. They always had enough film area to have sharpness under control, and so they could use the degrees of freedom in a lens design in pursuit of other characteristics. 135 format lenses, on the other hand, had too small a negative for proper sharpness, and so the lenses tried to make up for this by stressing the designs more, and using higher contrast coatings, and so on.

What I see in medium format shots (I also had a Sinar eMotion 54LV at some point, a 22MP CCD 36x48mm sensor, and shoot enough MF film) is more relaxed transitions from in-focus to out-of-focus, and between colours. Not all lenses are the same, of course, but I tend to buy Zeiss, even in MF.



Jul 05, 2013 at 10:19 AM
carstenw
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p.7 #4 · p.7 #4 · Yesterday's medium format digital backs


mortyb wrote:
Hmm, I was sure they had CCDs. But yes, you're right. Maybe it's the Kodak processing that I really like (SLR/c, Pro Back, Pentax 645D). But there was a quite significant change in colors from Nikons DSLRs with CCD and CMOS. This has been debated endlessly on DPR among other forums. The question is of course: Was this due to change in sensor type - or was it simply a choice made wrt. processing.

alundeb, it's not about color differences alone, of course there are differences between sensors and cameras. But I'm not the only one thinking older CCD cameras/backs have
...Show more

I personally think, as has been mentioned here already, that the reason for the great colours of the older CCD-based cameras is actually due to the denser CFAs used back when ISO 3200 with no noise wasn't a base requirement of every camera.

I truly wish that the manufacturers would pay much more attention to accurate and pleasing colour, just like it was back in the film days, with a range of products to satisfy everyone. I would swap my D800 for a D900 with a better CFA and better colour rendering in a heartbeat (and please remove the line-skipping in live view at the same time, please), but I haven't seen anything on the market which makes me want to give it up yet.



Jul 05, 2013 at 10:23 AM
RustyBug
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p.7 #5 · p.7 #5 · Yesterday's medium format digital backs


carstenw wrote:
Some of this is due to the more relaxed designs of the medium format lenses. They always had enough film area to have sharpness under control, and so they could use the degrees of freedom in a lens design in pursuit of other characteristics. 135 format lenses, on the other hand, had too small a negative for proper sharpness, and so the lenses tried to make up for this by stressing the designs more, and using higher contrast coatings, and so on.


This is part of why I like shooting MF M645 on FF . . . even though you are restricted to the FF crop, the projected image benefits from the latitude the lens designers were afforded by the larger format projection trig. This is a very different thing from trying to find a FF lens that will be "equivalent" to generate an MF look.



Jul 05, 2013 at 01:14 PM
Toothwalker
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p.7 #6 · p.7 #6 · Yesterday's medium format digital backs


RustyBug wrote:
This is part of why I like shooting MF M645 on FF . . . even though you are restricted to the FF crop, the projected image benefits from the latitude the lens designers were afforded by the larger format projection trig. This is a very different thing from trying to find a FF lens that will be "equivalent" to generate an MF look.


At least here we have two MF fans who write that MF lenses have less resolution. As far as the color and tonality advantage is concerned - I don't think so.





Jul 05, 2013 at 01:33 PM
RustyBug
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p.7 #7 · p.7 #7 · Yesterday's medium format digital backs


Toothwalker wrote:
At least here we have two MF fans who write that MF lenses have less resolution. As far as the color and tonality advantage is concerned - I don't think so.


What makes you say that? Did you not see the resolution numbers that Jim provided?

I certainly wasn't saying that MF lenses have less resolution, just that FF format designed lenses had to contend with a different set of challenges to lens design to contend with the smaller format, and along with it comes some of the issues that Makten pointed out about smaller format glass not providing the look of larger format counterparts.

Makten wrote:
No, more like seeing that there is no visible purple fringing, spherial aberration haze, extreme vignetting, terrible corner bokeh, severe LCA and other things.

Exactly. Just a few of the reasons (i.e. absence of above mentioned issues, etc.) why I like shooting M645 glass on FF.

As such, it is possible to get the excellent resolution across the frame that Jim provided data on, along with the optical qualities that Makten is lobbying for that are deemed as the "look". In that regard, I can get a bit of "best of both worlds" while still on FF ... without making the investment into a (marginally larger) "bargain" medium format digital back.

And before you get all bent about DOF @ some "equivalent" FF focal length/aperture that doesn't exist ... wide open is not the ONLY aperture that people shoot MF glass with (See tractor @ f8). Imo, that "equivalency" game as a reason why not to use something is a fools game (I played it for a while too). Instead, if you like the glass and the image it projects, shoot it ... if you don't like the image it projects, don't shoot it. Pretty simple.




Jul 06, 2013 at 01:23 AM
contas
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p.7 #8 · p.7 #8 · Yesterday's medium format digital backs


In the film age the lpmm or LP/mm stands for line pairs per millimeter.But in the digital age, where the sensors have too many sizes others unit like cycles/pixel, cycles/distance ... are applied.
For more :
http://www.imatest.com/docs/sharpness/



Jul 06, 2013 at 02:48 AM
alundeb
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p.7 #9 · p.7 #9 · Yesterday's medium format digital backs


RustyBug wrote:
What makes you say that? Did you not see the resolution numbers that Jim provided?



Both these give a resolution number of 64 lp/mm in the centre, but is it "every bit as sharp" in the centre at f/1.4 as at f/4?

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=772&Camera=453&Sample=0&FLI=0&API=0&LensComp=772&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=3

And these are both at "sensor limit", taken with the same sensor Jim used to measure 71 and 71. To me, it is not "every bit as sharp" at f/8 as at f/4.

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=481&Camera=453&Sample=0&FLI=0&API=5&LensComp=481&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=7



Jul 06, 2013 at 05:28 AM
Makten
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p.7 #10 · p.7 #10 · Yesterday's medium format digital backs


RustyBug wrote:
Exactly. Just a few of the reasons (i.e. absence of above mentioned issues, etc.) why I like shooting M645 glass on FF.



You missed that a 105/2.4 tele for FF would most likely have the same properties, but a 50/1.2 would definitely not (which is what you need to get the same look). So you are still not getting anything better (slow, FF medium teles are generally good to the corners anyway) by using an MF normal lens as a tele on a cropped sensor. Just a larger lens with an image circle that will light up the whole mirrorbox and lower the contrast.

Instead, if you like the glass and the image it projects, shoot it ... if you don't like the image it projects, don't shoot it. Pretty simple.

Exactly. Just don't fool yourself to believe that you will get the look of the larger format just because the lens was made for it.



Jul 06, 2013 at 11:02 AM
 

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jcolwell
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p.7 #11 · p.7 #11 · Yesterday's medium format digital backs


Hi Anders,

I'd appreciate it if you would be more careful about how you quote me, and how you interpret the data I provided. I described how those resolution tests were made, using the USAF 1951 resolution test target, which has discrete step sizes between measurement values.

Your following quotation of my input implies that I think lens performance for different conditions with the same USAF 1951 resolution test values are the same. I never said this. The same quotation implies that I said the Planar 85/1.4 is every bit as sharp at f/4 as at f/8. I didn't say that. Also, I note that you linked to a comparison of Planar 85/1.4 ZE lens performance at f/4 and f/8, while I clearly stated that I tested a Planar 85/1.4 MMJ C/Y lens. Does this mean you think results for a ZE lens are the same as for a C/Y lens?

alundeb wrote:
And these are both at "sensor limit", taken with the same sensor Jim used to measure 71 and 71. To me, it is not "every bit as sharp" at f/8 as at f/4.


What I actually said about "every bit as sharp" was this, ...

jcolwell wrote:
The Mamiya 645 A 300/2.8 APO is every bit as sharp all across the frame as the EF 300/2.8L IS, on a 1DsIII.


... which has nothing to do with the Planar 85/1.4 MMJ USAF 1951 test results that I contributed, nor with the Planar 85/1.4 ZE comparison that you linked. Moreover, my comments on the 300mm lenses are not based on USAF 1951 test results, rather they were based on years of experience with both lenses, on a variety of cameras.

If you want to see how the A 300/2.8 APO compares to the EF 300/2.8L IS on a D800, then maybe you could do us all a favour by buying these items and then showing us how it should be done. Don't forget to tell us how you attached the EF 300/2.8L IS to the D800.

Sincerely,
Jim





Jul 06, 2013 at 12:03 PM
alundeb
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p.7 #12 · p.7 #12 · Yesterday's medium format digital backs


jcolwell wrote:
Hi Anders,

I'd appreciate it if you would be more careful about how you quote me, and how you interpret the data I provided. I described how those resolution tests were made, using the USAF 1951 resolution test target, which has discrete step sizes between measurement values.

Your following quotation of my input implies that I think lens performance for different conditions with the same USAF 1951 resolution test values are the same. I never said this. The same quotation implies that I said the Planar 85/1.4 is every bit as sharp at f/4 as at f/8. I didn't say that.
...Show more

Hi Jim,

You are right that I made some mistakes when linking some of your earlier comments to the numbers presented.
Still I think that your measurement results show anomalies that are sure signs that they are not accurate.

I did not think the 85 MMJ and ZF are the same lenses. I found the Planar 85 ZF as the closest, to illustrate the universal behaviour that high quality lenses with maximum aprture f/1.4 lose visible MTF at f/8 compared to f/4. I checked about 15 lenses for that, and they all do it. The amount varies, between about 5% and 8% (going by PZ numbers).

Regarding discrete steps, a difference of 5% from 71 is 67 or 74. It should show up in your numbers.

The 300 2.8 L IS on the D800, now that is funny. Now you are distorting my words out of meaning as well
First, I mentioned both the D800 and the NEX 7. The 300 2.8 IS is a known quality reference to me, and it can be measured with the NEX 7. Second, I want alternatives to the 300 2.8 L IS precisely because it cannot be mountd on Nikon. If it could, I would just use it and not even think about the Mamiya. On top of, that, I cannot just go out and buy a 645 300 2.8 APO. One of the curses with alternative lenses, they are hard to find, many sellers don't ship to Norway (yes, as the only country, I don't know why), and you take a risk at what you get.

The technical points in my criticism of your measurements stand on their own, and they do not imply anything further than just what they are.

Hope to see you soon,

Anders


Edited on Jul 06, 2013 at 04:41 PM · View previous versions



Jul 06, 2013 at 01:00 PM
RustyBug
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p.7 #13 · p.7 #13 · Yesterday's medium format digital backs


Makten wrote:
You missed that a 105/2.4 tele for FF would most likely have the same properties, but a 50/1.2 would definitely not (which is what you need to get the same look). .


And you're missing the point that I'm not trying to change from one format to another where you have to play the silly "equivalency" game for fov. I'm still shooting on the same FF format and the change from the 80mm FF to 80mm MF does not necessitate any such thing at all. As a result, I'm changing from a projected image designed for FF to a projected image designed for MF.

Despite the fact that so many want to try to suggest I'm whack by introducing the "equivalency" comparison, this is a really simple thing. Consider this for a moment. If I mount an FF Nikon, Canon, Zeiss or Oly 24mm, I get a projected image that their engineers/designers created for the FF format. If I mount a 24L TS-E II, I get a projected image that was designed to project a larger image circle, but also for the FF format.

The drawing style differences between these lenses all exist because of the lens design. Absolutely NONE of it is attributed to the sensor/film. And, as you can readily see (hopefully), there is absolutely no need to employ an "equivalency" for going from the smaller image circle to the larger image circle regarding dof/fov. The lens projects its image, you capture a portion of that projection.

I agree that you can have "some" lower contrast by using the larger image circle. The micro-contrast of the 24L TS-E II is not the same as that of a Zeiss, and the drawing styles are rather different, but both are top flight glass. If you like the "look" of the Zeiss, you shoot it. If you like the "look" of the 24L TS-E II, you shoot it (only capturing the central portion of its projected image) and there is no "equivalency" requirement to accommodate for the larger image circle projection.

Mounting an MF lens of same focal length as its FF counterpart (i.e. MF 80mm= FF 80mm) will impart a different drawing style. The projected image of the MF lens will be exactly the same as it always projects, no matter what you mount it to, and here we have no need for an "equivalency".

Compared to capturing the projected image with a larger film/sensor area, you will only be capturing a central crop portion of that projected image. But, the attributes of that projected image remain unchanged ... from which the "look" is derived. And certainly, if you change your shooting position/perspective to capture an equivalent fov "as if" you (imaginarily were) shooting on MF, the dof changes will accompany that change will come along for the ride. But, even in the case of comparing fov @ 24x36 to 33x44, it would not require the magnitude of change to suggest for a 50/1.2 (and its optical design projection challenges).

But if you are shooting on the FF platform ... FF 80mm = MF 80mm and since there is no accompanying need for change your shooting position, there is no accompanying dof/fov "equialency" compensation to be made. Thus, you are only left with all the other attributes of the projected image that provide the "look" of an image projected from MF glass.

The image projection properties of a Leica M differ from the properties of Leica R (same film/sensor area format) ... largely rooted in the distance from which the image is projected (trig). The look difference is not because of the capture area ... it is because of the lens design variance that stemmed from the different angle of the projected image. Essentially, this is some basic trig regarding the light path projection and the angle of incidence of the light as the energy being transferred to the film/sensor. The angle of incidence is significant in that we are dealing with a vector quantity for the amount of energy that will be absorbed by the film/sensor.

The differences in those angles are rather observable in the form of some classic vignetting where the angles of incidence are a "glancing blow", while the center is receiving more direct energy transfer. For some folks, they absolutely love the "look" (contrast/vignetting) of Leica M that is predicated much upon the shorter distance and steeper angles of incidence. Thus, it is the projected image that is responsible for the "look", not the format (compare to Leica R of same format).

Now, simply apply these principles (inversely) to MF where the variance of the "look" (and how it transitions across the frame) is attributed to the fact that it is projecting from a different distance and this responsible for a different rate of change in the vector quantities of energy than a lens designed for a smaller format. This is (in part) why the "look" of MF is different from the "look" of smaller format glass.

The sensor/film only captures what is projected onto it. Thus, the "look" of any lens is due to the optical properties of the projected image. But, this is not the same as the degree of magnification required following capture that is being attributed to the "look". The "look" comes from the optical image projection as the glass has been designed, not the film/sensor size.


Edited on Jul 06, 2013 at 02:56 PM · View previous versions



Jul 06, 2013 at 02:32 PM
alundeb
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p.7 #14 · p.7 #14 · Yesterday's medium format digital backs


RustyBug wrote:
The drawing style differences between these lenses all exist because of the lens design.


That is a good point. The question is, do lenses of the same focal length designed for 645 format or 35 mm have much different design? I am asking because I don't know. Maybe for some focal lengths, like 55 mm. The Contax 645 3.5/55 is a Distagon, not typical for 50ish mm lenses for 35 mm format. And why did Zeiss choose Distagon design for the new ultra high performance 1.4/55?

And, the flange distance and exit pupil distance are two different matters. It is not given that MF lenses have longer exit pupil distance just because they have longer flange distance. But again, I am asking the optical experts on this.



Jul 06, 2013 at 02:56 PM
Toothwalker
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p.7 #15 · p.7 #15 · Yesterday's medium format digital backs


RustyBug wrote:
What makes you say that? Did you not see the resolution numbers that Jim provided?

I certainly wasn't saying that MF lenses have less resolution, just that FF format designed lenses had to contend with a different set of challenges to lens design to contend with the smaller format, and along with it comes some of the issues that Makten pointed out about smaller format glass not providing the look of larger format counterparts.


What made me say this, is the implication of what Carsten wrote, and what you seemed to agree with, namely that a larger format lens does not need to deliver the resolution of the smaller format lens, because the larger image area compensates for the loss. And I agree with that.

For each format there is variation in lens performance, and the better lenses for a larger format may be more than useful on a smaller format, certainly if the step is relatively small, such as from 645 to 24x36 mm. I am, however, not tempted to mount an 8x10" lens on my mobile phone, for more than one reason.

As the difference in format increases, you will also find that the maximum aperture of the lenses (for the larger format) decreases, in order to permit a reasonable image quality at a reasonable price. A direct comparison with a lens for a much smaller format is then only possible at apertures that hit diffraction, i.e., the comparison is not very meaningful.

Further, it seems that people mean different things by "medium format look" and that the discussions in this thread are clouded.








Jul 06, 2013 at 03:14 PM
RustyBug
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p.7 #16 · p.7 #16 · Yesterday's medium format digital backs


alundeb wrote:
That is a good point. The question is, do lenses of the same focal length designed for 645 format or 35 mm have much different design? I am asking because I don't know. Maybe for some focal lengths, like 55 mm. The Contax 645 3.5/55 is a Distagon, not typical for 50ish mm lenses for 35 mm format. And why did Zeiss choose Distagon design for the new ultra high performance 1.4/55?

And, the flange distance and exit pupil distance are two different matters. It is not given that MF lenses have longer exit pupil distance just because they have longer
...Show more

Thanks.

I agree that we can't make widespread automatic assumptions that all exit pupil distances will be longer just because of the longer flange distance. In the case of the TS-E II, the rear element is recessed quite a distance compared to other 24mm lenses that have more protruding rear elements. Thus, the correlation may be one that holds typically true, but not necessarily always. Tamron Adaptall glass typically uses a "recesessed" element to afford for being an interchangeable mount. As such, Tamron Adaptall kinda sits between typical 35mm format design and 645 design.

So, could some MF glass have protruding rear elements compared to FF glass with recessed rear elements and the two actually be rather close regarding the than distance/angle from which the projection originates ... sure, I just don't know of a good example of it to provide. But, recognizing that as a possibility shows that you are giving credence to the projected image more than the format itself ... cool.

Going on to other design aspects @ why Distagon vs. Biogon vs. Planar ... WAY outa my league. I just understand trig and vector quantities and how the transitions across the frame from MF / M645 glass are different from transitions across the frame coming from FF Leica M (etc.) ... and giving credence to the projected image as the source, not the capture area.

Thus, if you like the "look" of a projection across the frame that is "smoother", and that is what you like about the MF "look" (I do), grab some MF glass. If you like a look that is more contrasty with the vignetting, grab some rangefinder glass. They can both be mounted with more options than they were ever originally conceived for, but those various mounting options don't change the projected image that comes from them ... gotta love "Alt" and all that it affords to us.





Jul 06, 2013 at 03:19 PM
RustyBug
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p.7 #17 · p.7 #17 · Yesterday's medium format digital backs


Gotcha @ reason for reply. I didn't specify which aspects I was agreeing with, my bad.

Toothwalker wrote:
that a larger format lens does not need to deliver the resolution of the smaller format lens, because the larger image area compensates for the loss. And I agree with that.


Imo, this is likely something that I think we can all agree that the larger area affords some offsetting compensation potential. However, just because that potential affords lesser resolving MF lenses some compensatory benefit, it does not mean that MF lenses are necessarily less sharp. As noted by Jim's data, herein lies a mixed bag of myth and truth, with the myth that MF glass is always less sharp being the challenging part for many folks to re-consider.

For each format there is variation in lens performance, and the better lenses for a larger format may be more than useful on a smaller format, certainly if the step is relatively small, such as from 645 to 24x36 mm. I am, however, not tempted to mount an 8x10" lens on my mobile phone, for more than one reason.

+1 ... but I am tempted to construct a mount so I can shoot some of my Graflex glass on FF.

As the difference in format increases, you will also find that the maximum aperture of the lenses (for the larger format) decreases, in order to permit a reasonable image quality at a reasonable price. A direct comparison with a lens for a much smaller format is then only possible at apertures that hit diffraction, i.e., the comparison is not very meaningful.

+1 @ diffraction vs. physical aperture diff's between format/area (back to formula). While people often use this to refute why they can't be "equivalent" @ direct comparison, it also offers properties to be harnessed in the inverse/opposite utilization (i.e. stopped down vs. w/o) regarding diffraction/aperture relationships. All along, I've not really tried to present "equivalent" comparisons. It is this very fact that they are different that is something that can be harvested/harnessed to render a more MF look than you may be getting from FF glass, even if only on FF. I've only tried to suggest that the look of the projection remains the look of the projection.

Further, it seems that people mean different things by "medium format look" and that the discussions in this thread are clouded.


+1 @ ill-defined "MF Look" ... I like the smoother transitions that is projected (trig) and the well corrected optics created by the engineer/designers. Meahwhile, others may think that DOF is the holy grail of the MF look. When I want a lens that renders a subject with more micro-contrast, I'll grab for something other than my M645 glass.



I shoot a mixed bag of FF and MF, as well as a mixed bag of Oly, Nikon, Canon, Leica, Zeiss, Tamron. It's highly unlikely that you'll ever get me to say that any one of my lenses is better than another, as they all project different images with different "looks" that encompass the range of micro-contrast to color to bokeh to corner resolution to center resolution (Nikon vs. Oly @ notable) to CA to etc.. These differences exist within a format and across formats.

Now, I might say that Oly has bettter resolving corners in their 28/3.5 than the Nikon 28/2.8 AIS, but the Nikon has more central resolution in Zone A than Zone C. But, I likely won't say that the Oly is better than the Nikon when I'm wanting a lens that projects a contrasty central image. Neither will I say that the Nikon is better than the Oly when I want Oly colors. So it goes also, with FF glass vs. M645 glass at producing a different "look". The MF glass produces a more MF look than FF glass (design @ trig) and that can be captured (even if only the central crop).

Given the choice @ the marginal 33x44 vs. 24x36, I simply decided to to use the M645 glass which was designed to cover the larger 60x45 film area, even if only capturing 36mm at the most, whereas the most I could capture with the medium format sensor is 44mm. This represents about 20% diff in capture area, but, imo a projection that is more than 20% different in garnering the MF look because of its design to cover the larger area.

This is the reason that I suggested to the OP that if he didn't like the jump to only 33x44 for "yesterday's" medium format (or today's digital 645), he could still get some of the MF goodness from the projected imagery of MF glass, if willing to concede the difference between 44mm vs. 36 mm. Imo, this 20% difference amounts to debating a 16MP sensor vs. a 20MP sensor. It might sound like you're giving up a lot ... but are you really giving up a critical amount And is that 20% in real estate really the reason for the "look" of the larger format, or is it the projected image?

I realize that this still will likely not "convince" many folks of very much. But, I'm not really trying to convince anyone ... just explaining why I like MF glass on FF, even if it is going against the conventionally established. In a "regular" forum, I wouldn't ever mention it or waste my time, energy or breath on such things with people who I know would never appreciate any of this... but this is the Alt Forum, and this is FM (complete with one or two lurkers).








Jul 06, 2013 at 06:37 PM
mirkoc
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p.7 #18 · p.7 #18 · Yesterday's medium format digital backs


RustyBug wrote:
So, could some MF glass have protruding rear elements compared to FF glass with recessed rear elements and the two actually be rather close regarding the than distance/angle from which the projection originates ... sure, I just don't know of a good example of it to provide.



Could it be Mamiya 7 glass?



Jul 06, 2013 at 07:35 PM
alundeb
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p.7 #19 · p.7 #19 · Yesterday's medium format digital backs


jcolwell wrote:
I described how those resolution tests were made, using the USAF 1951 resolution test target, which has discrete step sizes between measurement values.


Ok, the steps in USAF1951 are in lp/mm

50.8
57.0
64.0
71.8
80.6

So the accuracy is even worse than I thought. Only two steps to cover the effect of the format difference from 36x24 mm to 44x33 mm.




Jul 06, 2013 at 08:26 PM
douglasf13
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p.7 #20 · p.7 #20 · Yesterday's medium format digital backs


alundeb wrote:
That is a good point. The question is, do lenses of the same focal length designed for 645 format or 35 mm have much different design? I am asking because I don't know. Maybe for some focal lengths, like 55 mm. The Contax 645 3.5/55 is a Distagon, not typical for 50ish mm lenses for 35 mm format. And why did Zeiss choose Distagon design for the new ultra high performance 1.4/55?

And, the flange distance and exit pupil distance are two different matters. It is not given that MF lenses have longer exit pupil distance just because they have longer
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Yeah, the exit pupil is simply the virtual image of the aperture that you see when looking through the rear of the lens. Just because one lens has a rear element closer to the sensor than another doesn't necessarily mean that the exit pupil distance to the sensor is shorter.




Jul 06, 2013 at 08:47 PM
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