Pentax 645 lenses on Fujifilm GFX

StonkinPix · Jul 23, 2021

Many thanks for your reply, Rob.

I ordered the Fotodiox Pro 645-GFX adapter (with aperture control) which arrived today. It's a big piece of kit and includes an Arca-Swiss tripod mount. It's very well made and has a precise fit to my 50R.

Thankfully it seems to control my 45 & 120 645 lens apertures quite well and I've had fun testing and looking at the results on Capture One. The latitude these lenses enable in PP with C1 is remarkable. I now need to practice on precise focussing - f11 or f16 with both lenses seems optimum, though I'm sure the 120mm Macro will lend itself to really good focus-stacking.

As has been previously mentioned many times, nothing beats Fujifilm's own GFX lenses but a) they're out of my reach financially, for now and b) these Pentax 645 lenses seem to be a good match for the 50R. I have been using Leica R lenses - 28mm, 90mm and 135mm. The latter is very good - but no macro possibility. The 28mm is no match for the GFX which needs to be set to 35mm format and even then there's vignetting. Same with the wider Voigtlanders I have.

So, until funds allow (and Fujifilm stock delivery to UK recovers!) I'm happy to persevere with the 645's.

I'll continue to look out for your comments in dpreview, as you're obviously the 'guru'. Many thanks.

Rob de Loe · Jul 23, 2021

StonkinPix said:
Many thanks for your reply, Rob.

I ordered the Fotodiox Pro 645-GFX adapter (with aperture control) which arrived today. It's a big piece of kit and includes an Arca-Swiss tripod mount. It's very well made and has a precise fit to my 50R.

Thankfully it seems to control my 45 & 120 645 lens apertures quite well and I've had fun testing and looking at the results on Capture One. The latitude these lenses enable in PP with C1 is remarkable. I now need to practice on precise focussing - f11 or f16 with both lenses seems optimum, though I'm sure the 120mm Macro will lend itself to really good focus-stacking.

As has been previously mentioned many times, nothing beats Fujifilm's own GFX lenses but a) they're out of my reach financially, for now and b) these Pentax 645 lenses seem to be a good match for the 50R. I have been using Leica R lenses - 28mm, 90mm and 135mm. The latter is very good - but no macro possibility. The 28mm is no match for the GFX which needs to be set to 35mm format and even then there's vignetting. Same with the wider Voigtlanders I have.

So, until funds allow (and Fujifilm stock delivery to UK recovers!) I'm happy to persevere with the 645's.

I'll continue to look out for your comments in dpreview, as you're obviously the 'guru'. Many thanks.

Happy to help. The adapter you bought has an extra feature that will allow you to control the Pentax 645 lenses that do not have on-lens aperture controls, e.g., the new 55/2.8.

If you're happy working on a tripod, I think you'll quite enjoy your Pentax lenses. Especially once you get to f/8, they're not giving up much of anything to the GF lenses.

StonkinPix · Jul 24, 2021

Thank you Nawlins.

Job sorted - Fotodiox Pro for 645 to GFX which includes and aperture control blade. It works well with my 45mm and 120mm Macro 645's so might go for a couple more mid-range lenses.

Beware newcomers to GFX with 645 lenses, some converters advertised are totally 'dumb' and aren't able to control the lens aperture. Pentax A 645 lenses do not directly control aperture from their in-built aperture ring - it's a bit weird but that's how it is.

Rob de Loe · Jul 24, 2021

StonkinPix said:
Thank you Nawlins.

Job sorted - Fotodiox Pro for 645 to GFX which includes and aperture control blade. It works well with my 45mm and 120mm Macro 645's so might go for a couple more mid-range lenses.

Beware newcomers to GFX with 645 lenses, some converters advertised are totally 'dumb' and aren't able to control the lens aperture. Pentax A 645 lenses do not directly control aperture from their in-built aperture ring - it's a bit weird but that's how it is.

When they introduced the 645D camera, Pentax made some lenses for "digital" that had an aperture ring, were updated optics, and could also cover 645 (HD Pentax-D FA 645 35mm F3.5 AL [IF]), some that covered 645 but had no aperture (SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW), and some that had no aperture ring and only covered the 33mm x 44mm sensor (SMC Pentax-DA 645 25mm F4 AL [IF] SDM AW).

It is indeed confusing! However, Pentax has a very loyal and organized user community. There's detailed information and user reviews at the Pentax Forums website. Here's the link for Pentax 645 lenses (all flavours): https://www.pentaxforums.com/lensreviews/SMC-Pentax-645-Medium-Format-Lenses-i4.html

StonkinPix · Aug 15, 2021

Hi Rob

Well, it's now a month since I asked for help regarding the Pentax-A 645 lenses on a GFX 50R and a very much appreciated your helpful reply.

I purchased the Fotodiox Pro P645(a) - GFX adapter, direct from Fotodiox USA. This adapter includes an aperture control ring (operating on the 645 aperture lever and seems to cover the full aperture range of each lens - though the actual f-stop on the lens isn't known. My lens' apertures are all set to 'A'. With practice it's fairly intuitive where you are with the aperture opening.

One or two other contributors seem to think that any 'dumb' adapter will control the aperture. I don't have any other brands but looking at images of such (e.g. on eBay) they do look to be completely 'dumb' and therefore I can't see how the aperture of 645 lenses can be controlled. I may be wrong, but I'd strongly advise anyone thinking of going down the P-A 645 route to do some detailed research on the aperture control issue.

In your reply, Rob, you suggested 3 particular P-A 645 lenses - the 35mm f3.5; 75mm f2.8; and 150mm f3.5. I also have (as previously mentioned) the 45mm f2.8 and the 120mm Macro. Whilst all but the Macro are quite short (body length), the Fotodiox adapter protrudes by 4cm when fitted. Remarkably, the 75mm is just less than 4cm in length and the 150mm only 7cm. The 35mm is a beast, though, also at 7cm and with a 77mm filter size.

As yet, I don't have a strong favourite, though 28mm (FF) has long been by go-to FL for streets & hols. This equates to the 35mm 645 - though the combination of 50R + adapter + 645 35mm isn't something I'd recommend to take on holiday! In that respect, my Leica Q is still the best walkabout camera I've ever used.

Our local Camera Club resumes in a few weeks time and I'm really looking forward to testing the GFX / 645 combos (and myself!) in a photo-competition environment. I'm not artistic, compared to a number of other members, so I'll have to rely on the technical prowess of this camera and these really good 645 lenses.

I still can't get over how relatively inexpensive they are on eBay and what such good build quality. Hopefully, I'll have some images worthy of posting on this forum, in a month or so.

Bye for now

Rob de Loe · Aug 15, 2021

StonkinPix said:
Hi Rob

Well, it's now a month since I asked for help regarding the Pentax-A 645 lenses on a GFX 50R and a very much appreciated your helpful reply.

I purchased the Fotodiox Pro P645(a) - GFX adapter, direct from Fotodiox USA. This adapter includes an aperture control ring (operating on the 645 aperture lever and seems to cover the full aperture range of each lens - though the actual f-stop on the lens isn't known. My lens' apertures are all set to 'A'. With practice it's fairly intuitive where you are with the aperture opening.

One or two other contributors seem to think that any 'dumb' adapter will control the aperture. I don't have any other brands but looking at images of such (e.g. on eBay) they do look to be completely 'dumb' and therefore I can't see how the aperture of 645 lenses can be controlled. I may be wrong, but I'd strongly advise anyone thinking of going down the P-A 645 route to do some detailed research on the aperture control issue.

In your reply, Rob, you suggested 3 particular P-A 645 lenses - the 35mm f3.5; 75mm f2.8; and 150mm f3.5. I also have (as previously mentioned) the 45mm f2.8 and the 120mm Macro. Whilst all but the Macro are quite short (body length), the Fotodiox adapter protrudes by 4cm when fitted. Remarkably, the 75mm is just less than 4cm in length and the 150mm only 7cm. The 35mm is a beast, though, also at 7cm and with a 77mm filter size.

As yet, I don't have a strong favourite, though 28mm (FF) has long been by go-to FL for streets & hols. This equates to the 35mm 645 - though the combination of 50R + adapter + 645 35mm isn't something I'd recommend to take on holiday! In that respect, my Leica Q is still the best walkabout camera I've ever used.

Our local Camera Club resumes in a few weeks time and I'm really looking forward to testing the GFX / 645 combos (and myself!) in a photo-competition environment. I'm not artistic, compared to a number of other members, so I'll have to rely on the technical prowess of this camera and these really good 645 lenses.

I still can't get over how relatively inexpensive they are on eBay and what such good build quality. Hopefully, I'll have some images worthy of posting on this forum, in a month or so.

Bye for now

What a great update! Thanks.

Yes, the adapter does add a fair bit of length so that the lenses can be at the correct flange distance.

The "dumb" adapters (no ring, just a tube with a mechanism to operate the lever that closes down the aperture) work with lenses that have the aperture control ring on the lens. your adapter will also control the modern ones like the FA 55/2.8, which has no ring.

The 35mm f/3.5 A lens is a superb optic. It's much bigger than the tiny 75/2.8, but I don't find it to be too massive. I think you'll enjoy using it.

Cheers, Rob

JimKasson · Aug 15, 2021

Rob de Loe said:
The "dumb" adapters (no ring, just a tube with a mechanism to operate the lever that closes down the aperture) work with lenses that have the aperture control ring on the lens. your adapter will also control the modern ones like the FA 55/2.8, which has no ring.

I consider all adapters with no electronics in them to be "dumb".

Rob de Loe · Aug 15, 2021

JimKasson said:
Rob de Loe said:

The "dumb" adapters (no ring, just a tube with a mechanism to operate the lever that closes down the aperture) work with lenses that have the aperture control ring on the lens. your adapter will also control the modern ones like the FA 55/2.8, which has no ring.

Click to expand...

I consider all adapters with no electronics in them to be "dumb".

Mea culpa. I agree.

StonkinPix · Sep 14, 2021

Thank you Rob.

After a month or two of practice, I'm getting used to the finer points of the 50R with Pentax-A lenses. The critical point is Aperture control in that I'm finding medium to smaller aperture (say f8 - f16) produces best results on the P-A lenses - unless you're bravely going for say f2.8 on the 45mm or even f3.5 on the 35mm.

The Fotodiox adapter doesn't confirm the actual F stop - unless the lens aperture control is set to what you want. In most situations I set the lens' aperture ring to A. Then I'm getting used to fine tuning of the f-stop control ring on the adaper. It's not perfect but, at the end of the day, the P-A lenses adapted to GFX 50 are producing really good images - providing focus is sharp. The latter point (no pun) is really the most important one.

GFX cameras with non-GF lenses rely on manual focus, etc. They're a cheaper option than true GFX lenses (when you can get them) but you have to persevere. I can take decent hand-held street shots at 1/60s f5.6, but I'm finding ISO above 1500 on GFX50R does compromise the RAW images.

On the other hand, in studio with flash (at 1/125s) the GFX 50R with P-A lenses (especially the 120mm Macro) can produce stellar results. Obviously on tripod and generally focus-stacked.

To anyone thinking of going GFX 50 (as opposed to 100) on a budget, buy a good 2nd hand 50 (S or R) and start out with a Fotodiox adapter for Pentax-A lens + the Pentax-A 45mm or 75mm lens. They're both great lenses to use and get used to this GFX system. Remember, though, that medium format is more ponderous to use than than FF or APS-C. Don't expect to go out and take great photos of busy children or sports action. Get a strong tripod and set it all up for 'still life'. Then you'll be amazed!

Rich42 · Sep 14, 2021

StonkinPix said:
To anyone thinking of going GFX 50 (as opposed to 100) on a budget, buy a good 2nd hand 50 (S or R) and start out with a Fotodiox adapter for Pentax-A lens + the Pentax-A 45mm or 75mm lens. They're both great lenses to use and get used to this GFX system. Remember, though, that medium format is more ponderous to use than than FF or APS-C. Don't expect to go out and take great photos of busy children or sports action. Get a strong tripod and set it all up for 'still life'. Then you'll be amazed!

Re: " Remember, though, that medium format is more ponderous to use than than FF or APS-C"

I think you would find that the word "ponderous" is not in the vocabulary of the GFX 100S at all.

Do expect to go out and take great photographs of busy children and a whole lot more sports action than you think.

Strong tripod and still life? Well, certainly, if you want to. But, better yet, be prepared to see all manner of hand-held photography that you'll swear looks like the camera had been on a tripod, courtesy of the camera's image stabilization.

This was handheld in dim twilight

https://2.img-dpreview.com/files/p/E~forums/65473214/a148216ddb2a41f3ba87b61b4afaeb28

;-)

Rich

Rob de Loe · Sep 14, 2021

StonkinPix said:
Thank you Rob.

After a month or two of practice, I'm getting used to the finer points of the 50R with Pentax-A lenses. The critical point is Aperture control in that I'm finding medium to smaller aperture (say f8 - f16) produces best results on the P-A lenses - unless you're bravely going for say f2.8 on the 45mm or even f3.5 on the 35mm.

The Fotodiox adapter doesn't confirm the actual F stop - unless the lens aperture control is set to what you want. In most situations I set the lens' aperture ring to A. Then I'm getting used to fine tuning of the f-stop control ring on the adaper. It's not perfect but, at the end of the day, the P-A lenses adapted to GFX 50 are producing really good images - providing focus is sharp. The latter point (no pun) is really the most important one.

GFX cameras with non-GF lenses rely on manual focus, etc. They're a cheaper option than true GFX lenses (when you can get them) but you have to persevere. I can take decent hand-held street shots at 1/60s f5.6, but I'm finding ISO above 1500 on GFX50R does compromise the RAW images.

On the other hand, in studio with flash (at 1/125s) the GFX 50R with P-A lenses (especially the 120mm Macro) can produce stellar results. Obviously on tripod and generally focus-stacked.

To anyone thinking of going GFX 50 (as opposed to 100) on a budget, buy a good 2nd hand 50 (S or R) and start out with a Fotodiox adapter for Pentax-A lens + the Pentax-A 45mm or 75mm lens. They're both great lenses to use and get used to this GFX system. Remember, though, that medium format is more ponderous to use than than FF or APS-C. Don't expect to go out and take great photos of busy children or sports action. Get a strong tripod and set it all up for 'still life'. Then you'll be amazed!

Thanks for the thorough update. I'm glad to hear it's working out for you. I'm especially pleased to hear that you like the 45/2.8.

Rob

ed_f · Feb 7, 2022

as I need the lenses only for repro-use I bought two 645-lenses for my 100s. for the same reason I also decided for the cheapest adapter. adapts well, but I can only use the 3 most open apertures.

the aperture lever in the lenses are smooth-running and always spring back to open aperture. with the adapter the last stage to fully open aperture is also difficult with it and neither moves beyond the second aperture. the lever of the lens is "in front" of the lever of the adapter (looking into lens + adapter from the back and from the top), it's to the right of it. when stopping down with the adapter, as i understand it, something blocks the lens lever from the second stopping down position and it doesn't move any further ... AND I even cannot move the lenses lever further! I don't really understand it. does anyone has an idea how to get this working?

thanks!

marco1974 · Feb 7, 2022

Get a better adapter. Really.

Been there. Tried to fix it. Failed. Purchased a Kipon one, it just works.

Marco

AudiiDudii · Feb 7, 2022

ed_f said:
as I need the lenses only for repro-use I bought two 645-lenses for my 100s. for the same reason I also decided for the cheapest adapter. adapts well, but I can only use the 3 most open apertures.

the aperture lever in the lenses are smooth-running and always spring back to open aperture. with the adapter the last stage to fully open aperture is also difficult with it and neither moves beyond the second aperture. the lever of the lens is "in front" of the lever of the adapter (looking into lens + adapter from the back and from the top), it's to the right of it. when stopping down with the adapter, as i understand it, something blocks the lens lever from the second stopping down position and it doesn't move any further ... AND I even cannot move the lenses lever further! I don't really understand it. does anyone has an idea how to get this working?

I'm afraid I can't make any sense of what you've written, but I do own that exact adapter and the apertures worked (and continue to work) perfectly straight out of the box for all six of the P645 A and FA version lenses I've mounted on it to date. <scratches head>

That said, be warned that the female bayonet is attached to the adapter body via six M1.6 screws. On my adapter, with the 870 g 45-85/f4.5 zoom attached, they failed and the lens -- with the bayonet still attached! -- fell off the camera, damaging the lens. <shrug>

marco1974 · Feb 7, 2022

AudiiDudii said:
That said, be warned that the female bayonet is attached to the adapter body via six M1.6 screws. On my adapter, with the 870 g 45-85/f4.5 zoom attached, they failed and the lens -- with the bayonet still attached! -- fell off the camera, damaging the lens. <shrug>

Ouch!

One more reason to get a quality adapter!

ed_f · Feb 7, 2022

although i am "subscribed to updates" i do not receive any (spam included).

my adapter has on one side 5 black screws, on the other 4 blank ones. so maybe not the same? they are all firm and in place. does yours look like that? the lever visible is NOT going smoothly at all ... as I have it I would really like to get it to work. hope you can help!

Michael Floyd · Feb 7, 2022

ed_f said:
although i am "subscribed to updates" i do not receive any (spam included).

my adapter has on one side 5 black screws, on the other 4 blank ones. so maybe not the same? they are all firm and in place. does yours look like that? the lever visible is NOT going smoothly at all ... as I have it I would really like to get it to work. hope you can help!

That looks identical to the lens mount on my adaptor, although mine works smoothly. It is a very simple mechanism and utterly repairable. Buy or borrow yourself a JIS screwdriver in the appropriate size and dismantle that thing. Start with the 5 screws shown here and follow your nose, you will see how simple it is. You will see what needs to be done, whatever it is.

I'm happy to talk you through it with images if you need. Alternatively take it to anyone that works with small mechanical things, (engineer, jeweller, watch maker, the clever guy down the street who is always making weird things etc etc etc), take a lens too so he/she can check operation.

AudiiDudii · Feb 7, 2022

ed_f said:
although i am "subscribed to updates" i do not receive any (spam included).

my adapter has on one side 5 black screws, on the other 4 blank ones. so maybe not the same? they are all firm and in place. does yours look like that? the lever visible is NOT going smoothly at all ... as I have it I would really like to get it to work. hope you can help!

I'm not Marco1974, but this is the same adapter I have used with my FrankenKamera VIII project.

I bought it instead of other adapters specifically because the bayonet portion was held in place via five screws, which meant I could readily remove it then modify it to work for my project.

The aperture tab is tensioned by a long spring that stretches nearly half way around the adapter and it should move easily and smoothly from one end of the slot to the other.

If it doesn't, there's your problem and you should return it to the seller; if it does, then the problem is with your lenses. (Although it strikes me as highly unlikely that all three of your lenses would fail to perform properly in exactly the same way, so I suspect it's the adapter that's at fault here.)

If you can't return the adapter for a replacement, you could do as I have done, which is to remove the internal tab and spring mechanism and replace it with an external rubber band or O-ring like so:

I don't necessarily recommend this approach (or this adapter, for that matter) but I had no choice because I needed to reduce the thickness of the lens mount, so the aperture tab / spring mechanism had to be removed and its functionality replaced using another method.

FWIW, it works perfectly and the lens will mount on the lens adapter (and the lens cap will mount on the lens) without any issues after it's been modified this way. That said, YMMV!

Michael Floyd · Feb 7, 2022

Not saying that anyone else is mistaken, just relating my experience...

There are many brandless Chinese adaptors and it goes without saying that some are better than others. The P645>GFX one that I have is the very first adaptor that I've owned, out of quite a few, that needed no adjustment or truing out of the box. This includes several more expensive brand name ones - although not I admit, any Novoflex which I don't doubt are excellent.

Can't believe I'm defending cheap Chinese products, Lol. That is so counter to my position on the situation. Regardless, appraise the unit in front of you rather than the reputation is my advice.

JimKasson · Feb 7, 2022

Michael Floyd said:
Not saying that anyone else is mistaken, just relating my experience...

There are many brandless Chinese adaptors and it goes without saying that some are better than others. The P645>GFX one that I have is the very first adaptor that I've owned, out of quite a few, that needed no adjustment or truing out of the box. This includes several more expensive brand name ones - although not I admit, any Novoflex which I don't doubt are excellent.

In my experience, Novoflex adapters are too short by design.

Michael Floyd said:
Can't believe I'm defending cheap Chinese products, Lol. That is so counter to my position on the situation. Regardless, appraise the unit in front of you rather than the reputation is my advice.

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