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05-25-2012, 06:31 AM   #1
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Pentax 645 to Nikon 35mm adapter?

Hi All,

Was just looking at adapters that allow mounting of Pentax 645 lenses onto Nikon DSLR's. Although there are a number of manufacturers of this kind of specific adapter (allowing mounting of Pentax 645 lenses onto Nikon DSLR's), it appears there are two variants from what I read and see. Some allow the proper mounting but have no lever that allows stopping down the aperture diaphragm as one turns the aperture ring on their lens. Therefore the lens remains wide open all the time especially that 645 lenses don't have a switch on the side of the barrel allowing aperture closing. The other kind of adapter does allow closing down the aperture. Any recommendation of a specific brand/type of adapter? Thanks in advance!

Dave (D&A)

05-31-2012, 08:40 PM   #2
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QuoteOriginally posted by DandA Quote
Hi All,

Was just looking at adapters that allow mounting of Pentax 645 lenses onto Nikon DSLR's. Although there are a number of manufacturers of this kind of specific adapter (allowing mounting of Pentax 645 lenses onto Nikon DSLR's), it appears there are two variants from what I read and see. Some allow the proper mounting but have no lever that allows stopping down the aperture diaphragm as one turns the aperture ring on their lens. Therefore the lens remains wide open all the time especially that 645 lenses don't have a switch on the side of the barrel allowing aperture closing. The other kind of adapter does allow closing down the aperture. Any recommendation of a specific brand/type of adapter? Thanks in advance!

Dave (D&A)
Where do you see an adapter that allow you to control the diaphragm from the body, not even the genuine Pentax 645 to K adapter can do that. The only adapter that I know of which can control the diaphragm from the body is the genuine Pentax 67 to 645 adapter (I don't think I've seen an aftermarket one of these).

Pentax A lenses unmounted to an adapter, do not show any response to the aperture ring being turned. When the lens is mounted on an adapter, the diaphragm opens and closes as the aperture ring is turned in one direction then the other. No adapter including the Pentax 645 to K adapter has any linkage which can be controlled from the body. None of the adapters being sold on eBay show any sort of external control except for the lens lock button or lever. Shooting with P645 lenses on my Pentax K20D, is strictly Av mode, stop down metering and I can't imagine it would be any different with other brands of DSLR.

I'd suggest you get the cheapest one from eBay, they all seem to be built the same; plated brass on the lens side and black anodized aluminum to the body.
05-31-2012, 11:21 PM   #3
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QuoteOriginally posted by excanonfd Quote
Where do you see an adapter that allow you to control the diaphragm from the body, not even the genuine Pentax 645 to K adapter can do that. The only adapter that I know of which can control the diaphragm from the body is the genuine Pentax 67 to 645 adapter (I don't think I've seen an aftermarket one of these).

Pentax A lenses unmounted to an adapter, do not show any response to the aperture ring being turned. When the lens is mounted on an adapter, the diaphragm opens and closes as the aperture ring is turned in one direction then the other. No adapter including the Pentax 645 to K adapter has any linkage which can be controlled from the body. None of the adapters being sold on eBay show any sort of external control except for the lens lock button or lever. Shooting with P645 lenses on my Pentax K20D, is strictly Av mode, stop down metering and I can't imagine it would be any different with other brands of DSLR.

I'd suggest you get the cheapest one from eBay, they all seem to be built the same; plated brass on the lens side and black anodized aluminum to the body.
Hi,

I think you might have mis-understood what I wrote (or maybe I didn't explain it clearly). I've been shooting Penatx medium format and 35mm for over 35 years and am quite familiar how the lenses and their apertures work. What I found out is some of the Pentax 645 lens to Nikon adpaters down have a internal level inside of them that rests against (pushes on) the 645 lens aperture linkage, so that the 645 lens always remains wide open and turning the 645 lens aperture ring does nothing to stop down the lens to a shooting aperture. Then there are other brands who designed their Pentax 645 to Nikon adapters to have a littlke internal lever that pushes on the 645 lens aperture linkage and therefor when the 645 lens/Nikon adapter is used together and mounted on a Nikon camera, turning the 645 lens aperture rings DOES stop down the 645 lens.

So all the Pentax 645 to Nikon adapters "are not" the same in terms of functioning and these differences are important!

Dave
06-01-2012, 01:23 AM   #4
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This might not help but I bought a 67 to NIkon adapter which you can only shoot wide open with. Works great, though. Esp. the 165/2.8 on a Nikon gives the pictures quite a special feel & look. I hardly use it, though.
As it is with these adapters: I forgot the name of the brand. Something from China. And it cost 60 Euros or so.

The ones that let you change the aperture must cost a heck of a lot more, I guess. I haven't found one, yet. There are so many out there, you quickly lose track.


Last edited by phonoline; 06-01-2012 at 06:15 AM.
06-01-2012, 08:31 AM   #5
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QuoteOriginally posted by phonoline Quote
This might not help but I bought a 67 to NIkon adapter which you can only shoot wide open with. Works great, though. Esp. the 165/2.8 on a Nikon gives the pictures quite a special feel & look. I hardly use it, though.
As it is with these adapters: I forgot the name of the brand. Something from China. And it cost 60 Euros or so.

The ones that let you change the aperture must cost a heck of a lot more, I guess. I haven't found one, yet. There are so many out there, you quickly lose track.
Hi Photoline,

Although some of the time, the adapters (Pentax 645 to Nikon) that do allow stopping down the 645 lens aperture do cost more than the ones that don't, there have been a few that actually cost around $65-$75. They often sell out though and are not easy to find. Although sometimes shooting wide open is noce, in most cases, using a 645 lens on 35mm really does need/benifit from stopping down, so finding an adpater that allows this will give the best of both worlds.

Dave
06-01-2012, 11:10 AM   #6
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Dave: Here is the Rainbowimaging adapter. I put an arrow pointing to what "looks like" the lever to close down the diaphragm. Looking at the back of one of my 645 lenses, and where the lens lever is, this adapter lever looks to be in the correct location to do what we want. For 40 bucks, I may just take a chance on it. I have a half dozen of their various adapters for my NEX 7 and the quality/workmanship are "OK" but they all work and focus to infinity.
Good luck
Dave
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06-01-2012, 11:28 AM   #7
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QuoteOriginally posted by DandA Quote
Hi,

I think you might have mis-understood what I wrote (or maybe I didn't explain it clearly). I've been shooting Penatx medium format and 35mm for over 35 years and am quite familiar how the lenses and their apertures work. What I found out is some of the Pentax 645 lens to Nikon adpaters down have a internal level inside of them that rests against (pushes on) the 645 lens aperture linkage, so that the 645 lens always remains wide open and turning the 645 lens aperture ring does nothing to stop down the lens to a shooting aperture. Then there are other brands who designed their Pentax 645 to Nikon adapters to have a littlke internal lever that pushes on the 645 lens aperture linkage and therefor when the 645 lens/Nikon adapter is used together and mounted on a Nikon camera, turning the 645 lens aperture rings DOES stop down the 645 lens.

So all the Pentax 645 to Nikon adapters "are not" the same in terms of functioning and these differences are important!

Dave
Show me the adapter that won't let you close down the diaphragm when you turn the aperture ring, I have yet to see any such useless adapter regardless of the mount. Since none of the adaptive body can control the diaphragm from the body, your choice of adapter is clear; get the adapter that allow you to open and close the diaphragm with the aperture ring.

Here is the cheapest one I found that describes how the adapter works: Pentax PK 645 Lens to Nikon F Mount Adapter D7000 D300S D90 D200 D3 D2X D5100 | eBay

Here is more expensive one with a description: pentax 645 645N lens adapter to Nikon D3 D90 D700 D300 | eBay

There are other eBay merchants that sell the Pentax 645 to Nikon adapter and when there is a description of the adapter's function, they either say "manual diaphragm control" or "stop down mode". Just buy from a merchant who describes the adapter's function, you will have some recourse should the adapter fail to function as described.
06-02-2012, 05:33 AM   #8
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QuoteOriginally posted by excanonfd Quote
Show me the adapter that won't let you close down the diaphragm when you turn the aperture ring, I have yet to see any such useless adapter regardless of the mount. Since none of the adaptive body can control the diaphragm from the body, your choice of adapter is clear; get the adapter that allow you to open and close the diaphragm with the aperture ring.

Here is the cheapest one I found that describes how the adapter works: Pentax PK 645 Lens to Nikon F Mount Adapter D7000 D300S D90 D200 D3 D2X D5100 | eBay

Here is more expensive one with a description: pentax 645 645N lens adapter to Nikon D3 D90 D700 D300 | eBay

There are other eBay merchants that sell the Pentax 645 to Nikon adapter and when there is a description of the adapter's function, they either say "manual diaphragm control" or "stop down mode". Just buy from a merchant who describes the adapter's function, you will have some recourse should the adapter fail to function as described.
Maybe you haven't seen one and I have no idea how may you have ordered, received and then tried them first hand on a Nikon body you had.....but I can tell you from 1st hand experience that there are Pentax 645 lens to Nikon adapters that DO NOT allow closing down the 645 lens adapter. I know, it sounds silly to design such a adapter, but they exist, more than you can imagine. I've previously spoken with long time Pentax 645 camera users (many shooting with Pentax 645 film bodies and now asome with the 645D) who have ordered a variety of these different adapters and quite a few made the mistake of assuming they all should be able to close down the 645 lens aperture..but they didn't! So it's best not to suggest that they all do and just go ahead an order any one listed. That is a mistake!

I also was at a camera show a few months ago and a dealer had a used one (no brand on the adapter) and it too didn't close down the 645 lens aperture. If you do a web search, you will find someone's post on some old forum describing such a problem with the Pentax 645 to Nikon adapter. He too posted he had one adapter that didn't close down his 645 lens aperture and a different one that did! I'm certainly not going to play roulette and order one adapter after another and try them and then return for a refund each one if they are the type that only allows you to use the lens wide open.

Lastly if you think the descriptions that some merchants post for their adapters (which all they do is buy from some distributor) is always accurate, that is also incorrect. They often just type a generic descriptions that applies to many of their different types of adapters they sell, but unfortunately the descriptions have glaring errors for certain types of their adapters. The adapter recommended above (of which I just ordered), mentions the adapter has a built in tripod mount!!! What do you think the chances are that this small thin adapter has a built in tripod mount? My money is on "zero" chances! Just one of many examples of why you cannot just go by some of these product descriptions as you suggested (certainly for all these various adapters). Thats why I posted and asked first prior to ordering and not just make assumptions. It's the prudent thing to do.

Dave


Last edited by DandA; 06-02-2012 at 05:41 AM.
06-02-2012, 05:35 AM   #9
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QuoteOriginally posted by gurtch Quote
Dave: Here is the Rainbowimaging adapter. I put an arrow pointing to what "looks like" the lever to close down the diaphragm. Looking at the back of one of my 645 lenses, and where the lens lever is, this adapter lever looks to be in the correct location to do what we want. For 40 bucks, I may just take a chance on it. I have a half dozen of their various adapters for my NEX 7 and the quality/workmanship are "OK" but they all work and focus to infinity.
Good luck
Dave
Hi Dave,

As I posted on Getdpi,in a more lengthy response, this adapter looks promising and I ordered one. If you read my post directly above this one, you'll see why I was so appreciative of your suggestion about this brand adapter. Thanks ever so much and hopefully in a week or so, we'll see how it works.

Dave
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