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Pentax 645 lens mount to Nikon converter/adapter?

D

D&A

Well-known member
Hi All,

Sort of taking a line from Tim's post regarding a lens adapter to Mamiya mount lenses to a Nikon DSLR....I'm looking for a adapter that allows mounting of Pentax 645 lenses to a Nikon DSLR.

There are quite of few aftermarket ones, but many don't allow stopping down the aperture of the Pentax 645 lens once mounted on the Nikon body since there is no actuation level in the adapter to do this. I'm looking for a well constructed one and also one that has the actuation lever so I can use the Pentax 645 lens at any chosen aperture. Thanks!

Dave (D&A)
 
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M

mbroomfield

New member
They are not made (to my knowledge) with a seperate actuation lever, rather they simply link the aperture and stop down levers on the lens so that the aperture ring works as normal.

I have a couple of these for EF, but I bought them a long time ago and don't recall the make.
 
D

D&A

Well-known member
mbroomfield said:
They are not made (to my knowledge) with a seperate actuation lever, rather they simply link the aperture and stop down levers on the lens so that the aperture ring works as normal.

I have a couple of these for EF, but I bought them a long time ago and don't recall the make.
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Thanks very much for your reply! When I said have an actuator lever, I meant the adpater makes contact with the lens aperture linkage at the back of the lens, which allows one to stop down the Pentax 645 lens to any aperture (exactly as you described). Some adapters are able to do this, some cannot and the lens must be shot wide open. I'm looking for the name of the ones that have this feature (ability).

Dave (D&A)
 
O

Oren Grad

Active member
Apologies if I'm missing something, but I still don't understand the question. Pentax 645 A and FA lenses, like Pentax film-era 35mm format lenses, have aperture rings. If you mount one on an adapter that doesn't have an aperture lever coupling, the aperture should function fully manually and you should be able to stop it down just by turning the aperture ring.
 
S

sergio lovisolo

Member
With 645 lenses you preset the aperture, but the lens stays open until the lever forces it to close, exactly the contrary of, say, nikon lenses.
Sergio
 
D

D&A

Well-known member
sergio lovisolo said:
With 645 lenses you preset the aperture, but the lens stays open until the lever forces it to close, exactly the contrary of, say, nikon lenses.
Sergio
Click to expand...
Hi All,

I appreciate all the responses so far but not sure if I am any closer to a solution.

Dave, I'm not sure how the adapter you linked to, works either. From the look of it I don't believe it interacts with the rear aperture stopped down lever and thus the lens always remains wide open, regardless what the aperture ring is set to. I think there was a post somewheres made years ago sliding to the issue with this particular adapter...but it's worthy trying to contact them and I thank you for both the link and suggestion.

Sergio is quite correct and his explanation is the reason why using the Pentax 645 lenses with an adapter, is so important that the adapter allows the lens to be stopped down to shooting aperture by automatically pushing on the rear aperture lever while the lens is attached to the adapter.

It is just the opposite of how Pentax 35mm lenses work when not attached to a camera body.

There is one brand I know of that definitely works, but can cost when new almost 3-4x the price when found used and all I know is that it isn't the only brand that will work in the way I described. So for now, the search goes on for a definite answer. Thanks again everyone!

Dave (D&A)
 
D

D&A

Well-known member
Antonio Chagin said:
Hello, I have the PT645 Nikon adapter. Is well constructed found sometimes in Ebay from Shamghai, China. Right now is not listed but used to be:
Pentax 645 PT645 PT 645 lens Adapter to Nikon AI D70S | eBay
OR:
Adapter Ring PT645 - AI

It has a lever that allows diaphragm. I'm very happy with it. Also the 645 lenses are superb. I have the 35A, 45-85FA, 120 Macro and 1.4 Ext.
You find some distortion which is thoroughly corrected in ACR.
Good luck.
Click to expand...
Hi Antonio,

Thanks very much for the info. From what I see, on one listing he is all sold out of it...but when I search another way, it looks like it is still available with 3 of 10 sold! I don't know which is accurate and if it is available or not. There are others that don't have any screws on the lens mount and this would have me worried. At least I can see the aperture lever inside the adapter they show. It looks like the same adapter that Dave suggested from Fotodiox, but the lever cannot be seen with the Fotodiox one. Why some adapters would not have the aperture lever allowing the lens diaphram to stop down I cannot understand. Anyhow, I'm hoping to find the exact one Antonio recoomended,. Good to hear the Penatx 645 lenses perform well on Nikon DSLR's. Many medium format lenses due to resolution differences and designed for a larger area (and therefore don't need as much resolution as their 35mm counterparts), don't often perform all that well when mounted on 35mm format. Again many thanks.

Dave (D&A)
 
G

gurtch

Well-known member
I emailed Photodiox with a link to this thread to allow them to comment. Hope this is within the bounds of the forum (i have no ties to them), but I am very interested in a proper adapter.
Dave in NJ
 
D

D&A

Well-known member
gurtch said:
I emailed Photodiox with a link to this thread to allow them to comment. Hope this is within the bounds of the forum (i have no ties to them), but I am very interested in a proper adapter.
Dave in NJ
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Dave you beat me too it and as always you're one (sometimes two) steps ahead of me :) Thanks for doing this and looking forward to their response. I can see where this adapter might be extremely useful for those that shoot with Pentax 645 lenses and Nikon SLR bodies.

Dave (D&A)
 
G

gurtch

Well-known member
Dave (D&A): I am especially anxious to try my 120mm A macro, and 300mm A with dedicated 1.4X on the D800E (when it arrives).
Best....
Dave
 
D

D&A

Well-known member
gurtch said:
Dave (D&A): I am especially anxious to try my 120mm A macro, and 300mm A with dedicated 1.4X on the D800E (when it arrives).
Best....
Dave
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Dave, looking forward to doing similar things to with the 645 lenses on the D800. Lets hope you get a answer soon regarding the adapter. Thanks!

Dave (D&A)
 
D

D&A

Well-known member
Hi Dave & All,

I just came across a webpage showing the Fotodiox 645 Lens to Nikon adapter and a single review was posted. The poster said although the adapter appeared to be well constructed, the issue with this adapter was that it didn't allow for the 645 lens to be stopped down...just as we discussed. He said the Rainbow brand adapter did allow stopping down the 645 lens but that adapter wasn't quite as well constructed as the Fotodiox. Of course maybe the Fotodiox adapter has been upgraded by now (after that reviewer posted their comments) in allowing allow 645 lenses to be stopped down. Unfortunately I'm not sure what the precise answer is at this point.

Dave (D&A)
 
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Antonio Chagin

Antonio Chagin

Member
Hi Dave well this is not an artistic image, just a quick example of lens detail. When I get some spare time I will do some ok comparisions. ACH
 
D

D&A

Well-known member
Antonio Chagin said:
Hi Dave well this is not an artistic image, just a quick example of lens detail. When I get some spare time I will do some ok comparisions. ACH
Click to expand...
Antonio, now your images are showing up! With the 1.4x on the 120 f4, they look very promising and they clearly show this. Thanks!. I am currently testing the 1.4x on the Fa 300 f4, FA 400 f5.6 and A* 600 f5.6. Once thing I noticed in my preliminary testing, is the 1.4x does lower the original contrast of the image when used on one of the telephoto lenses I mentioned.

Dave (D&A)
 
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