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02-29-2016, 02:24 AM   #1
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645 lens to K-mount adaptor

I have a 645z and 28-45. I am thinking of getting the K1 and 15-30. I am also considering getting a 75 f2.8 and possibly a 120mm macro. My concern is heading on a trip somewhere that I will have a failure or breakage of the 645 so I intend the K1 to be my backup but for this to work I need to use the adaptor obviously. Pentax don't seem to sell them new at least I can't find any.

Can someone tell me about these and how they are to use. Do you get aperture control and exif data etc. I don't care about the AF but I want to be able to use my 645 lenses on the K1 the same as I would on the Z, is that possible?

02-29-2016, 02:38 AM   #2
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QuoteOriginally posted by Gyroscope Quote
Can someone tell me about these and how they are to use. Do you get aperture control and exif data etc. I don't care about the AF but I want to be able to use my 645 lenses on the K1 the same as I would on the Z, is that possible?
The 645 to K adapter is simply a hollow tube with an aperture stop-down lever. As such, 645 lenses without an aperture ring can unfortunately not be used, as they will always stop down to the minimum aperture. This would preclude the use of the 28-45mm, though the 75mm and 120mm should be fine as long as you employ the stop-down metering procedure.

Pentax has not expressed any immediate plans to develop an AF/AE compatible 645 to K adapter. I believe the genuine adapter is no longer in production, but many third-party options should be available around the web.

If you do end up getting a K-1, my suggestion would be to grab the 15-30mm and use older manual lenses (i.e. K, M or A lenses) or budget DA lenses like the 35mm F1.4 or 50mm F1.8 to fill the remaining gaps. This should minimize costs while maximizing image quality.

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02-29-2016, 02:39 AM   #3
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Don't even bother asking this one mate. I have bashed this to death and gotten nowhere.

Pentax are a bunch of idiots for not thinking about this as an option for 645 users, heck, we have spent enough after all.

Also, so much for all the ''in the know'' K-1 beta testers that told me "just hold on, you will love it", ''it will be the best thing'' rubbish about being able to use the K-1 with 645. It just is not going to happen.

I am happy to be proven wrong, but I doubt it will happen.
02-29-2016, 03:32 AM   #4
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Interesting. I guess the K1 with 15-30 will still function as a backup to the 645+28-45 (much better backup than my Canon 5d3 and 17-40 anyway) plus it gives me my ultrawide and night shooting. Frankly the 645+28-45 combo does me for most of my landscape shots but it is handy to have something telephoto sometimes so perhaps I should just get something for K-mount as suggested - D-FA 100 macro? The 36mp is still going to be pretty good and certainly acceptable for those less common shots. I'm sure as hell not buying and carrying another Z for backup!!

Yes you would think Pentax would be developing a new adaptor..

02-29-2016, 06:09 AM   #5
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QuoteOriginally posted by Gyroscope Quote
I have a 645z and 28-45. I am thinking of getting the K1 and 15-30. I am also considering getting a 75 f2.8 and possibly a 120mm macro. My concern is heading on a trip somewhere that I will have a failure or breakage of the 645 so I intend the K1 to be my backup but for this to work I need to use the adaptor obviously. Pentax don't seem to sell them new at least I can't find any.

Can someone tell me about these and how they are to use. Do you get aperture control and exif data etc. I don't care about the AF but I want to be able to use my 645 lenses on the K1 the same as I would on the Z, is that possible?
K1 is an excellent choice as a back up to the 645Z.

I do have a 645 to K adapter. I bought it from Fotodiox. It is a little pricier than the eBay offerings. I learned the hard way. In my Canon days, I bought a Pentax 67 to Canon adapter from Ebay for my only Pentax 6x7 lens. It did not focus properly at infinity. I ended up getting one from Fotodiox and it did work properly. Physically the two adapters look identical. For some reason the cheeper one stops just short of infinity for sharp focus. Subsequently, I ended up buying all my adapters from Fotodiox. As I mentioned they are pricier but they are backed by a good warranty and they WORK.

I have used my A120 macro on my Pentax K5iis and K3 with excellent results. The crop factor makes the field of view equal to a 180mm lens. On K1 the crop factor should be 1:1 or close to it. The adapter, as Adam mentioned is a hollow tube with no automation. It is usable in stopped-down mode only.

There maybe another surprise to come from Pentax regarding the use of 645 lenses on K1. I remember references to it in the rumors. Somewhere deep in the K1 specifications there is a reference to a large file size produced by K1. This maybe the rumored 645 lens combo. It is exactly the same size as the files produced by 645Z! I am surprised this feature has not been announced or questioned. If true, this would make the K1 the most versatile full frame DSLR out there. If we are lucky, this 645 adapter would be fully automatic making all new and old FA 645 lenses usable as if they were a fully automatic K-mount lenses.

Last edited by btnapa; 02-29-2016 at 06:12 AM. Reason: more text
02-29-2016, 07:27 AM   #6
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An updated ring with at least an aperture ring like the K to Q mount adapter sounds reasonable at the very least. I'm surprised Novaflex or some Fotodiox doesn't make one. Is it even physically possible given the flange distance differences?
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