[diforbes]

Hello,

I'm considering adapting Pentax 645 lenses to a future purchase of a Fuji GFX 50r. My most-used 35mm equivalent field of view lenses on my Fuji X-T3 are 35mm and 85mm. I would like to buy older Pentax primes in these equivalent focal lengths, and perhaps a 28mm equivalent as well. I appreciate any insights and recommendations. Thanks!

[ProfessorBuzz]

The 645 35mm is excellent, the 90mm, and 120 Macro are very good as well.

[diforbes]

The 645 35mm is excellent, the 90mm, and 120 Macro are very good as well.

Thank you!

[-Linus-]

But is the 90mm Macro supportet by your adapter?
This lens has no aparature ring.

[wa2kqy]

Hi,

I have given this some thought myself. On the GFX, I'd opt to use my A 120 macro, FA 200, and A* 300/4 primes. As others have noted, there are others to consider as well. I would get just the Fuji 45-100 zoom to begin with and use the Pentax lenses. Even the FA 80-160 zoom. At least for a while.

I picked up the FA 200 because it was said that the A 200 wasn't nearly as good. So, I suppose I ought to repeat that for what it is worth. My plan was to cover 45-85 and 80-160 with zooms and the run primes at 200 and 300 plus the 1.4x and 2x TCs. I still need to get a 25, which is unlikely, or a 35 to finish out my plan.

As it stands right now, I think I would opt for the Pentax 645z for the 50 MP imager and not the Fuji 50s. Of course, I really want to get the Fuji 100, but that isn't in the bank account at this point in time. Maybe by the time I can afford one, Pentax will have a 645y (my own concept of a model number) with the 44x33mm 100 MP imager. Or, even a 645x (there I go again) with the physically larger 150 MP imager. That would give me a dilemma!

Stan

[torashi]

Since the GFX system is mirrorless, from what I've read, it's best to go for 35mm lenses, e.g. Pentax, Canon, etc. since many will cover the 44x33 mm sensor with astounding quality and small size. They would pair very well with the rangefinder style of the GFX 50R.
If you have a Pentax FA 43, you should try it out on the camera as a 35 mm field of view lens (with the appropriate adapter, for which you could take advantage of some store's return policies to see if it suits you), perhaps renting them first if you do not have them at hand. This would be a very compact combo.
For the 85mm field of view, you could try out the Canon 100/2 Supersonic, since the P67 105/2.4 is heavy, expensive and would be bulky with it's adapter.
I hope this helps in making a decision.

[diforbes]

Thanks for the reply. Interestingly, I was able to borrow a GFX 50r from my local camera store on two occasions and tried it out using vintage 35mm lenses. They work but to reduce the worst of the vignetting I needed to change the aspect ratio from 4:3 to 3:2, losing about 6MP of the sensor (still 45MP which is fine). And it's hard to go wider than a 35mm lens (about 28mm on the 50r) without more vignetting. I used the Pentax Super Tak 35mm 3.5 for that. I also tried some 45-57mm-range lenses (Minolta, Yashinon and some Russian and DDR stuff). Can't add a lens hood without introducing more vignetting.

Hence, I assumed that a 645 lens would cover the sensor better thus perhaps eliminating the need to change aspect ratios and vignetting at 4:3. I'm new to medium format and adapted lenses.

[angelo9978]

I'm waiting for my 50r to arrive also. I picked up a 67 55 f4 (latest version supposed to be sharpest in 67 format) and got at a good price from Japan. On my recently sold 645z (only b/c it needed service and the cost was not cheap) , I already liked my 645 A35mm (very sharp), 645 A75mmn (sharp), 645 FA 120macro (awesome sharp), 645 FA 300mm*(crazy sharp), and 67 120/2.4 (awesome portrait and sharp). I'll post pics when the camera finally arrives. It's been 3 weeks since backorder. I'd keep an eye on ebay for deals on those lenses, as you'd be surprised at some of the deals that pop out every few months. Lenses from Japan actually arrived faster than lenses from California, or a state near me, go figure. Just read the descriptions on the Japan sellers, they sometimes list "Mint" in title (I suppose as physical condition) but have haze in the optics. They will list haze in the description box though. But if it says glass is clear of any of those things in description box, Japan sellers are very thorough and accurate. Also, I picked up a lens spanner and tools, so was unafraid to get some lightly dusty lenses for cheap and cleaned them up. I'm not ocd either, and not the best in mechanical stuff, but am capable. Just google and hopefully get the same lens or similar lens dissambly video, and then video yourself and mark stuff with tape, and watch out for the aperture ring ball bearing from falling out (Trust me). You can score some good deals. Also, I'll try some of my Pentax K mount glass on the 50R. Just get here already.

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Last edited by angelo9978; 08-30-2020 at 09:27 PM. Reason: updated

[torashi]

Thanks for the reply. Interestingly, I was able to borrow a GFX 50r from my local camera store on two occasions and tried it out using vintage 35mm lenses. They work but to reduce the worst of the vignetting I needed to change the aspect ratio from 4:3 to 3:2, losing about 6MP of the sensor (still 45MP which is fine). And it's hard to go wider than a 35mm lens (about 28mm on the 50r) without more vignetting. I used the Pentax Super Tak 35mm 3.5 for that. I also tried some 45-57mm-range lenses (Minolta, Yashinon and some Russian and DDR stuff). Can't add a lens hood without introducing more vignetting.



Hence, I assumed that a 645 lens would cover the sensor better thus perhaps eliminating the need to change aspect ratios and vignetting at 4:3. I'm new to medium format and adapted lenses.

Yes, you should definitely use smaller hoods with FF lenses in MF. The same way one uses larger shades with FF lenses on APS-C cameras. The best example is the DA* 55/1.4 SDM. It needs a smaller hood on the K-1.
Since Canon has a 50mp camera, I suspect their modern offerings will be better suited for the 50r (plus AF and electronic aperture). I hope you can try out the FA43 since it's such a highly regarded lens for its rendition (aka pixie dust).

[diforbes]

I'm waiting for my 50r to arrive also. I picked up a 67 55 f4 (latest version supposed to be sharpest in 67 format) and got at a good price from Japan. On my recently sold 645z (only b/c it needed service and the cost was not cheap) , I already liked my 645 A35mm (very sharp), 645 A75mmn (sharp), 645 FA 120macro (awesome sharp), 645 FA 300mm*(crazy sharp), and 67 120/2.4 (awesome portrait and sharp). I'll post pics when the camera finally arrives. It's been 3 weeks since backorder. I'd keep an eye on ebay for deals on those lenses, as you'd be surprised at some of the deals that pop out every few months. Lenses from Japan actually arrived faster than lenses from California, or a state near me, go figure. Just read the descriptions on the Japan sellers, they sometimes list "Mint" in title (I suppose as physical condition) but have haze in the optics. They will list haze in the description box though. But if it says glass is clear of any of those things in description box, Japan sellers are very thorough and accurate. Also, I picked up a lens spanner and tools, so was unafraid to get some lightly dusty lenses for cheap and cleaned them up. I'm not ocd either, and not the best in mechanical stuff, but am capable. Just google and hopefully get the same lens or similar lens dissambly video, and then video yourself and mark stuff with tape, and watch out for the aperture ring ball bearing from falling out (Trust me). You can score some good deals. Also, I'll try some of my Pentax K mount glass on the 50R. Just get here already.

Thanks for the detailed reply. What would the difference be between 645 and 67 lenses on the 50r? Would 67 lenses cover the sensor better?

[Sykil]

The GFXs and digital 645s have the same sensor dimensions, and the 645 lenses are made to cover an even larger 6x4.5 negative — even the newer ones, I believe. They should cover the sensor just fine.

[angelo9978]

The GFXs and digital 645s have the same sensor dimensions, and the 645 lenses are made to cover an even larger 6x4.5 negative — even the newer ones, I believe. They should cover the sensor just fine.

Thanks for the detailed reply. What would the difference be between 645 and 67 lenses on the 50r? Would 67 lenses cover the sensor better?

the 67 lens is larger format so yes it would cover the sensor easily, and probably even use more of the center which is sharpest. the 645 should be no problem on the 50r because of same sensor size and what Sykil said. Also even some 35mm lenses are ok in the 50R. I hear the 43 limited is pretty cool on the 50R and I can't wait to test. Other photogs say the voigtlander 58mm f1.4 on the 50R is awesome also, so some slr lenses may behave well. I can't speak on edge to edge sharpness but I wouldn't use the slr lenses on the 50r for landscapes. My 50r hasn't arrived today yet, so I can't do a detailed test but I'll post samples from the lenses I will use on it.

Heres an example of what I believe was the 645 FA 35mm (had decentering issue right side soft and cropped photo) on the 645z if you want to pixel peep. There were many people around climbing and hiking near the arch so I cropped. https://artbyangelo.smugmug.com/Homepage/i-SJnkX8Z/A

[diforbes]

Thanks Sykil, torashi, angelo and others for your very helpful feedback!