[barondla]

Another forum has photos posted from a Pentax 645 FA 400 with a Fujifilm 1.4 converter and 100mp Fujifilm camera. The two optical assemblies worked well together and the photos look excellent. Surprised it worked so well.

Thanks,
barondla

[Ed Hurst]

I don't think it's totally surprising. Being mirrorless, the Fuji GFX cameras can easily handle the use of Pentax 645 lenses with an adaptor, especially the lenses with an aperture ring. Whether than adaptor + lens combo is mounted directly on the body or attached to a 1.4x converter shouldn't matter in terms of compatibility. If the lens itself is optically good (which the 645 FA 400 certainly is, so I'd expect it to work well with the needs of a 100MP camera); you're using the centre of the image circle; the lens is largely telecentric, so there should be no issue with the angle the light is striking the sensor or indeed the glass in the 1.4x converter; obviously you will need good camera/lens support to keep everything steady, but you would anyway regardless of camera used. All in all, you'd expect this combo to work well, I suggest :-). Nice to hear that it does though!

[pentaxus]

Some lenses just don't match up well. I had a Pentax FA 85mm 1.4 that just didn't work well with the Pentax 1.4X S teleconverter.

[Fogel70]

I don't think it's totally surprising. Being mirrorless, the Fuji GFX cameras can easily handle the use of Pentax 645 lenses with an adaptor, especially the lenses with an aperture ring. Whether than adaptor + lens combo is mounted directly on the body or attached to a 1.4x converter shouldn't matter in terms of compatibility. If the lens itself is optically good (which the 645 FA 400 certainly is, so I'd expect it to work well with the needs of a 100MP camera); you're using the centre of the image circle; the lens is largely telecentric, so there should be no issue with the angle the light is striking the sensor or indeed the glass in the 1.4x converter; obviously you will need good camera/lens support to keep everything steady, but you would anyway regardless of camera used. All in all, you'd expect this combo to work well, I suggest :-). Nice to hear that it does though!

It is impressive that a 100MP crop sensor with a 1.4x TC works well. Then the lens seems to have potential of supporting 350+ MP with a full frame 645 sensor, as it is only using a fraction of the full image circle.

[fuzz4brains]

Well, I wouldn't say that the Fuji 100 Mp sensor is only using a fraction of the full image circle.
It's not a crop sensor considering it's a GFX 100 (44x33 mm sensor i.e. the same sensor size as a 645 sensor (645Z).

[pid]

Some lenses just don't match up well. I had a Pentax FA 85mm 1.4 that just didn't work well with the Pentax 1.4X S teleconverter.

but the DFA*85/1.4 does well with the DA 1.4x Converter on FF! ... also the DFA*50/1.4 has nearly no vignetting with the APS-C Converter on FF

[robiles]

Well, I wouldn't say that the Fuji 100 Mp sensor is only using a fraction of the full image circle.
It's not a crop sensor considering it's a GFX 100 (44x33 mm sensor i.e. the same sensor size as a 645 sensor (645Z).

FA lenses are from the film era 645 cameras, and back then the frame size was 56x41.5 mm - that is 1,58x lager than the digital 645. Also the 1.4x TC makes the difference larger, as the image is further "croped".

I am not that good at math, but i would say no more than half of the image circle is used (which in some cases is considerably larger than the size of the frame format the lens was made for).

[TDvN57]

Just for reference, here are the Sony sensor specs for the MF sensors. I know it had been posted elsewhere but I thought it may help to clear up some information for some folks.

For example:
1) the 100mpx sensor is the same physical size as the now discontinued 51mpx sensor. Both are crop frame 645.

2) The 150mpx sensor is as near as dammit full frame 645 film. Near enough that I think it is reasonable to call it FF.

3) The pixel pitch for the 100mpx and the 150mpx is the same.

4) Incidentally the APC 24 and 26mpx cameras have a similar pixel pitch to the 100 and 150mpx sensors. That implies that if your old 6x7 and 645 legacy lenses can resolve enough details for the modern APC cameras it should most likely be able to resolve enough detail for the 100 and 150mpx sensors.

PS. For the folks that are a bit tired to read details, the first two pages in each document covers the specs for the monochrome sensors. So best to skip to page 3 and 4 of each document.

.

[SFTphotography]

4) Incidentally the APC 24 and 26mpx cameras have a similar pixel pitch to the 100 and 150mpx sensors. That implies that if your old 6x7 and 645 legacy lenses can resolve enough details for the modern APC cameras it should most likely be able to resolve enough detail for the 100 and 150mpx sensors.

PS. For the folks that are a bit tired to read details, the first two pages in each document covers the specs for the monochrome sensors. So best to skip to page 3 and 4 of each document.

.

Absolutely this. And on 100mp 44x33 you aren't using the whole image circle so lens softening on the corner won't be an issue at all.

It might become an issue on a full format MF digital sensor as the sensor of that size captures the whole image circle of the 6x7 and 645 legacy range - which might show up some short comings at the frame sides. Legacy glass works so well on crop MF as the poorer sides aren't being used giving that wonderful uniform centre to edge constancy loved by so many 645z users.

[texandrews]

of handling the higher mp crop sensors.....say all these Fuji experts. Guess using Pentax lenses on those Fuji bodies sort of puts the lie to that.

I have always just loved how internet experts deemed Pentax lenses inferior w/o any actual testing evidence. Maybe they are, maybe they aren't. Right now no one actually knows.

As far as a FF, or near FF sensor is concerned, my guess is that that will be more of a challenge for certain lenses. But some will be just fine. And really, while of course it would be ideal for the 645 lenses to all be new and fabulous, last time I looked I was making my way through a world that was a long way from ideal in so very many ways, and I'm managing, thank you very much. If Pentax makes a FF/near FF camera, I might just be able to deal with some vagaries in lens performance here and there, while I enjoyed the other aspects of the camera's goodness.

And of course, there could always be a crop mode, or just cropping here and there---like I already do for lots of my images for other reasons.

Sheesh....

[Fogel70]

Well, I wouldn't say that the Fuji 100 Mp sensor is only using a fraction of the full image circle.
It's not a crop sensor considering it's a GFX 100 (44x33 mm sensor i.e. the same sensor size as a 645 sensor (645Z).

A 44x33 mm sensor has a diagonal of 55 mm, out of the 69,7 mm diagonal of a FF 645.
A crop sensor with a 1.4x TC you crop down the image to using an diagonal of 39.2 mm of the optics (approx 31.5 x 23.6 size).

So with crop 645 and 1.4x TC less than a third of the optics is used compared to a FF 645 (without TC).
(So it is something like in between APS-C and MFT, compared to 35mm FF).

So if a crop smaller than 35 mm FF on 645 optics can handle 100MP, there may be hope that good 35mm FF lenses may also support 100MP. and good APS-C lenses may be able to handle 45MP.

[SFTphotography]

of handling the higher mp crop sensors.....say all these Fuji experts. Guess using Pentax lenses on those Fuji bodies sort of puts the lie to that.

I have always just loved how internet experts deemed Pentax lenses inferior w/o any actual testing evidence. Maybe they are, maybe they aren't. Right now no one actually knows.

As far as a FF, or near FF sensor is concerned, my guess is that that will be more of a challenge for certain lenses. But some will be just fine. And really, while of course it would be ideal for the 645 lenses to all be new and fabulous, last time I looked I was making my way through a world that was a long way from ideal in so very many ways, and I'm managing, thank you very much. If Pentax makes a FF/near FF camera, I might just be able to deal with some vagaries in lens performance here and there, while I enjoyed the other aspects of the camera's goodness.

And of course, there could always be a crop mode, or just cropping here and there---like I already do for lots of my images for other reasons.

Sheesh....

Re cropping - with a 150mp full format MF sensor - the aspect ratio alone would ensure the softer sides of the image circle were not being used, and a square crop from within that would remove the issue entirely. I'd love to see two Pentax 645 replacements - one a 100mp and two that full format 150mp. I would have room for both actually.

This is why 4:3, 5:4, 7:6 and 1:1 make for better shaped sensors than the 35mm of 3:2 as 3:2 gets closer the image circle edge where things are mushier.

[TDvN57]

If a lens covered the full image circle in film, why would it now not cover a FF sensor?

Image degradation towards the edges would have been flagged in the film days already.

Do we really believe that the super fine grain films and color positive films resulted at a lower resolution than a sub 4 micron pixel sensor?

Digitized film introduces another device in the workflow and IQ problems visible on a digitized picture should take that into account. The majority of scanners are very low resolution devices.

Edit:
I found this Wikipedia page that gives a layman's overview of how color film works and the main components.

https://en.wikipedia.org/wiki/Photographic_film

Regarding resolution it seems some comparison can be made between the size of the crystals used in the film with the size of the pixels in a digital camera. I know this is a stretch but it does give some "handle" on the subject. The halide crystals vary in size between 2 and 0.2 microns.

If this is some indication of the resolution capable with high end fine grain films then digital still has some ways to go before it can outpace resolution of film.

I stand to be corrected if I am way off on this comparison :-)