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10-02-2016, 06:27 AM   #436
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When designing a lens for an existing mount, the focal flange distance are set and not a choice of design. When designing a whole new mount and system, this distance may be chosen and thus affect were the empty space ends up. (with an exception for large aperture wide angles)

10-02-2016, 06:44 AM   #437
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The decision being made in 1975 doesn't make the logic invalid: the K-mount was designed not to waste space; regardless of long telephoto lenses allowing for longer registration distances. A mirrorless mount will be designed not to waste space.
But you're talking as if wasted space is the same as space from back element to the mount in certain optical designs. It's not. One affects all your lenses, the other just makes some of your lenses a bit longer.
10-02-2016, 06:51 AM   #438
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Smaller body - does it better?
10-02-2016, 07:06 AM   #439
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I'm not sure what you mean by that - if you're asking if I believe that a smaller camera body is always better, no, I definitely don't. I don't believe in an "one (small) size fits all" approach (especially when I buy shoes and clothing)
But don't mistake the lack of wasted space with a too thin camera design.

10-02-2016, 09:17 AM   #440
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QuoteOriginally posted by ogl Quote
Smaller body - does it better?
When I look at it, all theses smaller mirorless have bigger teles when we speak of the same actual focal length than what we get in pentax with FA50, DA70, FA77, DFA100 macro or F135. It is enough to need such focal/lengh to negate half the gain you may have on a WA or body. And nothing prevent you to design smaller K-mount bodies. Many film K-mount SLR where smaller/lighter after all and A7 or A7-II body are a bit larger/higher and a tad narrower than K01.

You could design just fine a K02, FF with EVF and have very similar size/weight as A7 or A7-II. Couting that you can get quite small/light WA on an FF if you want it (FA20 f/2.8 or some even smaller pancakes design), I am not sure there would be any drawback for the size of the lenses, all on the contrary. FA20, FA43, FA77 + K02 would very compact setup. And a 28-105 would pair well on it even if I am sure one could make a smaller collapsible design if that was the goal.
10-02-2016, 10:06 AM   #441
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QuoteOriginally posted by Simen1 Quote
Medium format would have the same dilemma about where to position the empty space. In the camera like K-01 or in the lens like Sony EF. However this may be solved in a good old fashion way: Using a fold out and bellow mechanism. This trick may reintroduce pocketable medium format and outmaneuver Fujifilm GFX and Hasselblad X1D (that uses the Sony EF strategy). Pentax could even use the usual 645 mount and full frame 645 sensors for this. Then introduce a thin and affordable D-FA 645 35mm f/5,6 XS landscape lens and I would sell everything but my underpants to get one.

Attachment 327498

Actually this is 6x9 so a 6x4,5 would need a smaller bellow and back, making it even more pocketable.
A thin and affordable D-FA 645 35mm f/5,6 XS landscape lens is an impossibility unless one gives up a lot on IQ (i.e., is willing to accept dark fuzzy corners). But who wants to spend thousands of dollars on a giant sensor camera that has a lomo lens? Moreover, a medium format sensor coupled with a slow lens provides no advantages over an FF sensor coupled with a modern fast lens.

As many have noticed, lenses for mirrorless cameras are not much smaller than lenses for mirrored cameras. The physics of gathering a useful amount of light and making all the rays converge without aberration, distortion, or light loss in the corners takes a significant amount of glass and space. From all that I've seen across all the formats, a decent aperture lens has a length (from sensor to filter ring) that' at least 1.3X the diagonal of the sensor (and that's for slow pancake lenses in a very narrow focal length range) and that all the faster, high-IQ lenses tend to be more than 2X the diagonal of the sensor and be filed with glass from front to back.

Sure, one can design a tiny slow lens on a collapsible bellows MF system, but then the mechanical bellows system would limit the use of longer focal length lenses, ultra-wide angle lenses, or fast lenses which all tend to weigh more than a kilogram. No doubt, one could make a pocketable MF system but apart from the bragging-rights factor of it, it's unlikely to deliver the performance and system-flexibility of a larger, more robust interchangeable lens system.
10-02-2016, 11:06 AM   #442
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I mean 645 camera body
10-02-2016, 12:37 PM   #443
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QuoteOriginally posted by photoptimist Quote
A thin and affordable D-FA 645 35mm f/5,6 XS landscape lens is an impossibility unless one gives up a lot on IQ (i.e., is willing to accept dark fuzzy corners). But who wants to spend thousands of dollars on a giant sensor camera that has a lomo lens? Moreover, a medium format sensor coupled with a slow lens provides no advantages over an FF sensor coupled with a modern fast lens.
Lets say f/8 then. Smaller aperture reduces the need for aberration-correcting lenses. At f/5,6 or 8 the lens construction can be very simple, and small, yet perform well. As a landscape lens it doesn't need large aperture and fast shutter speed. The MF advantage will be in resolution, not speed. Those who want top speed buys a Canon 1DX markII, not a 645, but neither will be pocketable.

10-02-2016, 02:26 PM   #444
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First SLR mounts were designed with four things in mind:
— the image size should cover 24mm x 36mm film
— lenses must be close to, or ideally be 100% telecentric (no cheating around with film)
— most popular focal lengths lenses must be relatively small.
— mirror must project image (which comes through the lens) to the pentaprism is satisfactory quality, which exceeds rangefinder quality.

And that's it. That is why all SLR mounts are variations of the same. It is all sound engineering, sound mechanics, no silly gimmicks. Even today, if sound engineering principles are to be followed, your average mirrorless toy should increase in size.
10-02-2016, 04:27 PM   #445
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QuoteOriginally posted by Simen1 Quote
Lets say f/8 then. Smaller aperture reduces the need for aberration-correcting lenses. At f/5,6 or 8 the lens construction can be very simple, and small, yet perform well. As a landscape lens it doesn't need large aperture and fast shutter speed. The MF advantage will be in resolution, not speed. Those who want top speed buys a Canon 1DX markII, not a 645, but neither will be pocketable.
Although feasible, it would be an extremely narrow niche camera (a Landscape Leica). It wouldn't even appeal to all landscape photographers because some need a wide range of focal lengths, do occasionally use wider apertures for subject isolation, and do other kinds of nature photography (macro, BIF, etc.) while in the field. The most portable rigs that address of a wider range of images are in the smaller formats because required image circle size

One can successfully design and sell special purpose cameras, but they need to be really inexpensive like GoPro or Ricoh Theta so that many people can afford to buy something with limited use. In contrast, the use of a high resolution MF sensor (and the digital horsepower to handle the output) makes the base price of this camera very high which automatically rules out most of the photographers. Worse, of the photographers that can afford expensive gear, most are going to look for flexibility (lots of lenses) and high performance (bright lenses, high frame rates, great AF etc.) to help justify the high price.

I'm not saying there aren't some photographers who wouldn't love a compact folding MF but the numbers are tiny compared to those buying bigger systems cameras.

P.S. Even at f/8, a wide angle landscape lens for 645 is not going to be small. If you really want pocketable, stay with smaller sensors.
10-02-2016, 04:31 PM   #446
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QuoteOriginally posted by photoptimist Quote
Although feasible, it would be an extremely narrow niche camera (a Landscape Leica). It wouldn't even appeal to all landscape photographers because some need a wide range of focal lengths, do occasionally use wider apertures for subject isolation, and do other kinds of nature photography (macro, BIF, etc.) while in the field. The most portable rigs that address of a wider range of images are in the smaller formats because required image circle size

One can successfully design and sell special purpose cameras, but they need to be really inexpensive like GoPro or Ricoh Theta so that many people can afford to buy something with limited use. In contrast, the use of a high resolution MF sensor (and the digital horsepower to handle the output) makes the base price of this camera very high which automatically rules out most of the photographers. Worse, of the photographers that can afford expensive gear, most are going to look for flexibility (lots of lenses) and high performance (bright lenses, high frame rates, great AF etc.) to help justify the high price.

I'm not saying there aren't some photographers who wouldn't love a compact folding MF but the numbers are tiny compared to those buying bigger systems cameras.

P.S. Even at f/8, a wide angle landscape lens for 645 is not going to be small. If you really want pocketable, stay with smaller sensors.
I would be absolutely stoked if this camera came out...I have no doubt it would give the A7rII a run for the money.
10-02-2016, 04:35 PM   #447
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QuoteOriginally posted by photoptimist Quote
Although feasible, it would be an extremely narrow niche camera (a Landscape Leica).
A niche lens doesn't make the camera a niche camera. Put on another lens if the one I suggest don't fit your needs.

QuoteOriginally posted by photoptimist Quote
P.S. Even at f/8, a wide angle landscape lens for 645 is not going to be small. If you really want pocketable, stay with smaller sensors.
It will. Just look at the 6x9 camera I posted and think of a downsize to half the sensor area. Also look at the thickness of the 105mm f/4,5 lens.
10-02-2016, 05:05 PM - 1 Like   #448
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QuoteOriginally posted by photoptimist Quote
Moreover, a medium format sensor coupled with a slow lens provides no advantages over an FF sensor coupled with a modern fast lens.
None of the MF lenses for 645 that Pentax sell play the very large apperture game and the crop factor toward FF is not so different. You buy an MF camera because the picture taken with it look better overall, not to achieve thiner dof.

The whole thing that one should use f/1.2 or f/1.4 lenses all of the time is quite overated, honestly.
10-02-2016, 05:12 PM   #449
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QuoteOriginally posted by Simen1 Quote
A niche lens doesn't make the camera a niche camera. Put on another lens if the one I suggest don't fit your needs.
Make the lenses interchangeable, and the camera is no longer pocketable. The required mount ring and added structural strength in the bellows adds bulk and weight.


QuoteOriginally posted by Simen1 Quote
It will. Just look at the 6x9 camera I posted and think of a downsize to half the sensor area. Also look at the thickness of the 105mm f/4,5 lens.
That's a "normal" lens, not a wide angle. Lens design does not scale just with focal length. The image circle matters and high-resolution lenses grow bigger as the focal length gets smaller than the image circle.
10-03-2016, 03:43 AM   #450
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QuoteOriginally posted by photoptimist Quote
Make the lenses interchangeable, and the camera is no longer pocketable. The required mount ring and added structural strength in the bellows adds bulk and weight.
I think you are being too categoric here. I was talking about having a mount all the time. Yes, a mount needs structural strength, but that doesn't mean its not possible to put it a pocket. Structural strength doesn't need a lot of space, and the system I suggest doesn't need to be able to hold a 600mm lens by the body without support under the lens, just like we don't do that with existing cameras ether. Large lenses will always be "lens with camera attached". Large lenses from 300mm usually have a tripod mount. Even a K-1 with a 70-200 is extremely unpractical to hold without supporting the lens barrel with one hand. I think you overdo the bulkiness needed for a mount.

QuoteOriginally posted by photoptimist Quote
That's a "normal" lens, not a wide angle. Lens design does not scale just with focal length. The image circle matters and high-resolution lenses grow bigger as the focal length gets smaller than the image circle.
Again, I think you overdo the difficulties. Small aperture lenses don't need a lot of space even if they are wide angles and need to cover a large image circle. The retrofocal design means the rear glass can be much smaller then the image circle. A little vignetting is easily correctable and it isn't much when image circle are smaller then the focal flange distance. Even a pinhole would vignette less then 1 stop in the corners of a 645 sensor behind a 70,87mm focal flange distance. Not that I'm suggesting a pinhole. The one niche lens I suggest added to the 645 system are not that diffraction limited. It should actually perform very well on resolution with f/8 aperture.

If you look at resolution charts they always start low at the large aperture end and lowest in the corners, because they are optically limited by not having enough aberration correcting lenses for that aperture and image circle. ("not enough" just mean its to many compromises involved, not that its an overall bad lens). Then the resolution increases to a top in the center around f/4-5,6 because the center are easiest corrected. Then the resolution increases to a top for the borders and corners around f/8-11 because its easier to correct the outer parts of the image circle when the aperture are even smaller. Then all of the resolution bars decreases tight together as the diffraction limitation are equal for the whole image circle. You can also see that resolution behavior of lenses are quite similar from f/8 an up regardless of its being a * lens or a DAL lens. This means that advanced lens formulas are a waste of money for small aperture photography, like in many landscape scenarios. The diffraction limitation relation to the f-number depends on pixel size. For small pixels like the Q (1,55 micron pixels) this top comes around f/4. For large pixels like the 6 micron pixels in 645D, the top comes around f/16. As we are discussing high resolution MF landscape photography, maybe 100 Mp on a 53,7x4,4mm sensor (4,6 micron pixels), that probably will top the corner resolution around f/11. It makes sense to aim for that aperture or a little larger to be able to adjust exposure around this top resolution aperture.

A lens like this would also be fantastic for other wide angle high resolution work as architecture and long exposure night landscapes (star trails, car light trails and such).

Remember, Ansel Adams was a member of the Group f.64, not the Group f1.4.

Last edited by Simen1; 10-03-2016 at 04:01 AM.
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