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07-29-2022, 08:31 AM - 1 Like   #1
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Adapting 645 lenses to GFX

I've ordered a GFX-50r that I'm still waiting to receive from Japan. Pretty excited to try it out and I was planning on adapting some lenses I've used with my 645D on it.
I read a little about aperture control and it sounds like the adapter needs to have this to properly use my 645 lenses at various apertures. So I ordered the Fotodiox Pro adapter with built in aperture control. But I've just had my Amazon order cancelled and it seems Fotodiox are also out of stock on this item (boo).
So I need to wait or find something else. Is there something else? That Stretch adapter looks interesting too but there is no mention of aperture control so I assume there isn't any.

Got any suggestions for me?
My 645 lenses are a mix of A and FA. I figured I'd probably get more mileage out of the A lenses since the lenses become manual when adapted and the A lenses are nicer for manual control.

Thanks!

Edit to add: just found a Pro adapter at Adorama so I've placed an order. But I'd still like to hear any words of wisdom on the topic if anyone has any for me.

07-29-2022, 01:10 PM - 1 Like   #2
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A forum member, Ed Hurst, has been using the Pentax 645 lenses with a Fuji GFX100S for a while and has made comments and replies several times about the adapters and his experiences. Checking his posts may give you good information.

Enjoy the new tool, I look forward to seeing what you capture.
07-29-2022, 01:14 PM - 1 Like   #3
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I think aperture control for adapters usually refers to the fact that most newer DA/DFA 645 lenses are missing the aperture ring and therefore to control via adapter, the adapter must have some sort of way to engage the aperture lever on the lens.

However, unlike K-mount lenses with an aperture ring, turning the aperture ring on 645 lenses (A and FA alike) does not stop down the lens instantly; you'll notice if you set the ring to, say, F22, the aperture stays wide open unless you flick one of the levers sticking out on the back of the lens. The adapter must have the ability to engage this lever to stop down the lens as the aperture ring is turned.

Pretty much any adapter *should* do this but the only experience I have is with the 645 to K mount adapter which indeed does this, but does not provide aperture control for DA 645 lenses. My guess is you'll find A and FA lenses will behave as expected with the adapter you ordered, and to the extent you don't see any control ring on the adapter, it won't fully support newer DA/DFA 645 lenses with no aperture ring.
07-29-2022, 01:59 PM   #4
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QuoteOriginally posted by jslifoaw Quote
I think aperture control for adapters usually refers to the fact that most newer DA/DFA 645 lenses are missing the aperture ring and therefore to control via adapter, the adapter must have some sort of way to engage the aperture lever on the lens.

However, unlike K-mount lenses with an aperture ring, turning the aperture ring on 645 lenses (A and FA alike) does not stop down the lens instantly; you'll notice if you set the ring to, say, F22, the aperture stays wide open unless you flick one of the levers sticking out on the back of the lens. The adapter must have the ability to engage this lever to stop down the lens as the aperture ring is turned.

Pretty much any adapter *should* do this but the only experience I have is with the 645 to K mount adapter which indeed does this, but does not provide aperture control for DA 645 lenses. My guess is you'll find A and FA lenses will behave as expected with the adapter you ordered, and to the extent you don't see any control ring on the adapter, it won't fully support newer DA/DFA 645 lenses with no aperture ring.
Ok, thanks. That does make perfect sense. I only have lenses with aperture rings so I don't need that feature.
Incidentally that order got cancelled too so they must get them all from Fotodiox on demand (or not when out of stock),.

I found a Kipon adapter in stock at B&H and have one of those on the way now.


Last edited by mattb123; 07-29-2022 at 02:05 PM.
07-29-2022, 02:19 PM - 1 Like   #5
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Hello! I can speak from experience of the Fotodiox Pro adaptor on a GFX100S - which I assume behaves in exactly the same way.

With 645 lenses that lack an aperture ring, the adaptor allows you to set an aperture manually - it grabs the stop-down lever on the back of the lens and stops down an increment that corresponds to where you have the ring. Totally manually. Please note that the ring on the adaptor, because it doesn't 'know' which lens it's attached to, simply lets you set a proportion of the aperture range of the lens. It isn't marked f2.8, f4, f5.6, etc. for this reason. So you need to work out roughly what the different markings on this aperture ring correspond to in terms of real aperture for each lens. At one point, I worked out (with a little help from a maths friend) what each marking exactly corresponds to, before I realised that the adaptor doesn't actually use the whole range of the markings; try to go to the fully stopped down end, and it doesn't get there fully in many cases. So, my habit for landscapes is just to throw the adaptor to about a mid range of the markings, and that seems to work fine. For astro, where I am using the lens wider open, it's a bit more of a guess.

If you lens does have an aperture ring, the adaptor behaves differently. First set the aperture on the lens, then when you turn the ring on the adaptor, it gradually stops the lens down until it reaches the aperture you selected on the lens; it won't go any further. So the lens aperture ring represents the correct setting you end up using, provided you turn the adaptor ring to the limit. In this way, it amounts to a preset - open it, and you can focus with the lens wide open; close it until the reaches the limit, and you are set to the aperture you chose on the lens.

Other P645 adaptors, that don't have the aperture ring (and so can only be used with 645 lenses that do have aperture rings), I assume behave more simply - they probably grab the stop-down lever on the lens and simply close it down continuously to whatever aperture you have the lens set to. But I don't know this for sure - the Fotodiox Pro is the only type of P645 adaptor I own. All I can say is that it's how I would design the simple adaptors if I were making them!

Hope this helps!

The process can be a bit slow, but for landscape stuff, that's no hardship most of the time and the results are good for me. The only caveat is that I do find some wide angle lenses perform in the corners worse in this adapted form than the did natively on my 645Z, even stopped down. It's not a huge problem, but it is there. The longer lenses don't have this issue.
07-29-2022, 02:59 PM   #6
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Thanks Ed! Since that Photodiox adapter is out of stock everywhere I'll soon know what the Kipon adapter does.
All my 645 lenses have aperture rings so it seems like that should simplify the adapter mechanics. I'll report back once I can try it out.
I never got anything wider than a 35mm on 645 so I also bought the 32-64 native lens to take care of that range. I was planning on using the adapter mostly on longer lenses so that should be ok.
Once my finances are recovered I'd consider that 23mm native lens too. Still less expensive than the 645 25mm last I looked!
07-29-2022, 03:04 PM - 2 Likes   #7
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Sounds like you're set.

I am holding out for the 20-35mm lens that is on the roadmap, to be released this year. If it performs well, it should cover the range where I currently see issues - and of course give me more wide angle coverage than I've ever had on a medium format system.

07-29-2022, 03:24 PM - 1 Like   #8
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QuoteOriginally posted by Ed Hurst Quote
Sounds like you're set.

I am holding out for the 20-35mm lens that is on the roadmap, to be released this year. If it performs well, it should cover the range where I currently see issues - and of course give me more wide angle coverage than I've ever had on a medium format system.
Thanks. That sounds like a very useful range!
07-29-2022, 05:36 PM   #9
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QuoteOriginally posted by Ed Hurst Quote
Sounds like you're set.

I am holding out for the 20-35mm lens that is on the roadmap, to be released this year. If it performs well, it should cover the range where I currently see issues - and of course give me more wide angle coverage than I've ever had on a medium format system.
Ed: Probably not as good as the forthcoming 20-35, but I've used a Canon 17-35/4 with pretty good results. Mild vignetting below 20 but perfectly usedable.

Matt: I've read where some people have used the Kipon 645 to GFX adapter. Doesn't have the aperture control like the Fotodiox does but would work in a pinch as long as your lens has an aperture ring. I've got the Fotodiox adapter and it's ok, though not 100% snug though. This is what the aperture ring looks like on the Fotodiox.

Last edited by cdd29; 07-29-2022 at 05:44 PM.
07-29-2022, 05:45 PM   #10
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for some reason it won't let me edit & add a pic but here's the aperture ring on the Fotodiox.
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08-18-2022, 04:04 PM   #11
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Something new for GFX and other brands for adapting Pentax 67 and 645 glass




08-19-2022, 06:48 AM   #12
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QuoteOriginally posted by Ed Hurst Quote
Sounds like you're set.

I am holding out for the 20-35mm lens that is on the roadmap, to be released this year. If it performs well, it should cover the range where I currently see issues - and of course give me more wide angle coverage than I've ever had on a medium format system.

That really is the lens for that system, that and the 45-100 and 100-200 would see landscape shooters pretty golden field of view wise.
08-19-2022, 07:43 AM   #13
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QuoteOriginally posted by cdd29 Quote
Ed: Probably not as good as the forthcoming 20-35, but I've used a Canon 17-35/4 with pretty good results. Mild vignetting below 20 but perfectly usedable.

Matt: I've read where some people have used the Kipon 645 to GFX adapter. Doesn't have the aperture control like the Fotodiox does but would work in a pinch as long as your lens has an aperture ring. I've got the Fotodiox adapter and it's ok, though not 100% snug though. This is what the aperture ring looks like on the Fotodiox.
My adapter seems nice and snug and well made. It's just a tube but a reasonably nice one. This is perfect for my needs as the lenses I'm adapting are all older 645 lenses with aperture rings. I've also added a 100-200 to my GFX kit so I've got things pretty well covered down to 32mm. Below that needs to be addressed but I'm going to give it a little time. I'd love that upcoming UWA zoom or the 32mm but my finances need to recover first. I'm hoping more third party manufacturers offer UWAs for the system at some point too.

Have any of you tried the Laowa 20mm f/4 Zero-D Shift gfx? That looks interesting and is a lot more affordable. I could live with manual focus if the IQ was good and the shift would be handy for architecture.
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