Which lenses to use on Pentax 645 (also 3rd party lenses?)

ashcorra · Nov 24, 2022

What lenses can I use with my Pentax 645? I know I can use the original Pentax lenses, I found a list of them online, and I got a couple of the zoom lenses. However, I am wondering if it is possible to venture outside of the specified Pentax 645 lenses? As in other brands, for example?

Also, my husband has some EF lenses that I would love to be able to use , is there such thing as an adapter for 645 to EF?

Any feedback would be appreciated, as I'm new to lenses. Thank you.

koraks · Nov 24, 2022

Welcome to Photrio!

I've taken the liberty to make the title of your post more descriptive so it will attract more relevant responses.

ashcorra said:
Also, my husband has some EF lenses that I would love to be able to use , is there such thing as an adapter for 645 to EF?

EF lenses are 35mm lenses and hence will have far smaller coverage than the 6x4.5cm film format of the Pentax 645. While technically an adapter is possible, and perhaps someone has even cobbled something together, it's not a particularly useful enterprise since every image will suffer from extreme vignetting. Besides, there's always the challenge of getting a 645 to talk with the EF lenses so that things like focus and in particular aperture control work. Concerning the latter, I hold very little hope. Although the EF protocol is basically an SPI (serial programming interface) and as such quite common in the world of electronics, not many camera enthusiasts or companies have undertaken the work of building effective/usable interfaces.

I can't really help you with the other questions, but I'm sure you'll get some more relevant responses.

Have fun using your 645 and I hope you'll enjoy your stay here on Photrio!

OAPOli · Nov 24, 2022

As far as I know, there are 3 adapters for the Pentax 645. One for the Pentax 67 lenses, which allows for auto diaphragm, and others for Hasselblad V lenses and Kiev 60 (or 88 via additional adapter) lenses which will work with manual stop down. There are also m65/m42 helicoid adapters if you want to get creative (e.g. projection lenses, leaf-shutter lenses, etc...)

Regarding the Canon EF, there are adapters to use the 645 lenses on a Canon body (and many others) but not the other way around.

grain elevator · Nov 24, 2022

Isn't a great advantage of that camera that the original lenses are somewhat affordable?
You can't use lenses for 35mm cameras even if they have a large image circle because the distance from film to lens flange on the P645 is too large to achieve anything but super close focus (thus for macro work it could be fine). You might however adapt other medium or large format lenses with two adapters via the aforementioned Hasselblad and P67 adapters. I will be cumbersome because you won't have automatic diaphragm.

ant! · Nov 28, 2022

As mentioned by the others, you can use other medium format lenses, when I had bought a bunch of Pentax 645 lenses together there was as well a Pentax 67 lens with the adapter in the mix. The manual Pentax 645 lenses are as mentioned quite affordable, I had ordered quite a few from Japan (from Yahoo Auctions Japan directly through a reshipper, was cheaper then through Ebay).
There is no need for the autofocus lenses on the Pentax 645, these are for the 645n and newer. Which lenses you like depends of course on your desired focal lenght, but since you mention the zooms: The 75mm is very nice and compact and the standard lens, the 55mm is an equivalent of 35mm on a "full frame" camera, the 150mm a nice short portrait tele. All quite compact, especially compared to the zooms.

Here is an overview over the different lenses of the systems, the reviews are often on the digital 645D / 645Z, but it gives you a good idea: https://www.pentaxforums.com/lensreviews/SMC-Pentax-645-Medium-Format-Lenses-i4.html

GregY · Nov 28, 2022

Ashcorra, Like others I've used the 645. The one I borrowed had both 645 lenses and 6x7 lenses w an adapter. Unlike the large format and the 35mm world especially the current digital market, in medium format it is very uncommon to find aftermarket lenses or adapters to change from one brand to another. I was recently given a 645 with a couple of lenses. My friend told me that when he was working for a publishing company in Italy he went out an bought the 45mm f 2.8 .....It cost 1 million lire !! and his boss gave him grief for not asking permission. At that time it was $1650 USD.... today you can find them on Ebay for under $200. The 300mm ED for around $300 USD for a clean one. Pentax lenses are great...and affordable.

ant! · Nov 29, 2022

Just a few more notes on the original Pentax 645 lenses:
- the manual only (which you should look for for the 645) are the "A" versions
- the autofocus versions and usually more expensive, but working fine in manual mode on the 645 are the "FA" versions. If you think about using the 645n one day, nothing wrong in these already now. But the other way around, "A" on 645n is fine as well.
- ignore the "D-FA" and "DA" versions, they are meant for the digital 645D and 645Z. While they technically work, some (all?) have no manual aperture control, are more expensive, and the "DA" probably covers not the full film format.
- special case: "LS" lenses are leaf shutter lenses (75mm or 135mm), for higher shutter speed with flash then the camera's flash sync time.

And when I say "affordable" (of course for quality medium format lenses), here some examples of what I had payed, from Japanese auctions. All prices in Canadian Dollar, shipping and importation tax not included. All in great used condition.:
- (all manual A version): 75/2.8 & 150/3.5 & 200/4 & LS 135/4 & adapter to Fuji G-mount. All for CAD 640. I sold the Fuji adapter for CAD 140, so this makes CAD 500. Buying a single new full frame lens is often more expensive.
- (most FA lenses) FA 35/3.5 & FA 45-80/4.5 & FA 80-160/4.5 & teleconverter 2x & Pentax 67 lens 135 & adapter Pentax 67->645, all for CAD 395. Sold the Pentax 67 lens for CAD 140, the adapter for CAD 100, which makes it CAD 155. The 35mm alone sells often for 300-400$. Compare this to the listed price at B&H for the lenses (current rebates): The 45-85 for USD 2,400, the 80-160 for USD 1,900, the (newer D-version) 35mm for USD 1,600.
- the A 55/2.8 for CAD 155 (and a few more longer FA lenses, all below CAD 200)

I think I bought not bad, but I guess with a bit more waiting you can find them even cheaper.

GRHazelton · Nov 29, 2022

Watch for the 35mm for the 645. It is truly excellent; coverage is similar to a 21mm lens in 35mm format. The 120mm f4 macro focuses down to 1:1 without any adapters; it also makes a good portrait lens. The 200mm f4 is very good. I own all the above plus the 55mm f2.8. All are very good. The 55mm lens makes a good walk-about lens, moderately wide but not too wide.

ashcorra · Dec 2, 2022

ant! said:
Just a few more notes on the original Pentax 645 lenses:
- the manual only (which you should look for for the 645) are the "A" versions
- the autofocus versions and usually more expensive, but working fine in manual mode on the 645 are the "FA" versions. If you think about using the 645n one day, nothing wrong in these already now. But the other way around, "A" on 645n is fine as well.
- ignore the "D-FA" and "DA" versions, they are meant for the digital 645D and 645Z. While they technically work, some (all?) have no manual aperture control, are more expensive, and the "DA" probably covers not the full film format.
- special case: "LS" lenses are leaf shutter lenses (75mm or 135mm), for higher shutter speed with flash then the camera's flash sync time.

And when I say "affordable" (of course for quality medium format lenses), here some examples of what I had payed, from Japanese auctions. All prices in Canadian Dollar, shipping and importation tax not included. All in great used condition.:
- (all manual A version): 75/2.8 & 150/3.5 & 200/4 & LS 135/4 & adapter to Fuji G-mount. All for CAD 640. I sold the Fuji adapter for CAD 140, so this makes CAD 500. Buying a single new full frame lens is often more expensive.
- (most FA lenses) FA 35/3.5 & FA 45-80/4.5 & FA 80-160/4.5 & teleconverter 2x & Pentax 67 lens 135 & adapter Pentax 67->645, all for CAD 395. Sold the Pentax 67 lens for CAD 140, the adapter for CAD 100, which makes it CAD 155. The 35mm alone sells often for 300-400$. Compare this to the listed price at B&H for the lenses (current rebates): The 45-85 for USD 2,400, the 80-160 for USD 1,900, the (newer D-version) 35mm for USD 1,600.
- the A 55/2.8 for CAD 155 (and a few more longer FA lenses, all below CAD 200)

I think I bought not bad, but I guess with a bit more waiting you can find them even cheaper.

Thank you so much, all very good answers but I think this one helped the most. I will be heeding some of your suggestions as I look for lenses right now! I think I will just forget about using the EF lenses, I wasn't dead set on using them anyway, just curious. Thank you all!

ashcorra · Dec 2, 2022

koraks said:
Welcome to Photrio!

I've taken the liberty to make the title of your post more descriptive so it will attract more relevant responses.

EF lenses are 35mm lenses and hence will have far smaller coverage than the 6x4.5cm film format of the Pentax 645. While technically an adapter is possible, and perhaps someone has even cobbled something together, it's not a particularly useful enterprise since every image will suffer from extreme vignetting. Besides, there's always the challenge of getting a 645 to talk with the EF lenses so that things like focus and in particular aperture control work. Concerning the latter, I hold very little hope. Although the EF protocol is basically an SPI (serial programming interface) and as such quite common in the world of electronics, not many camera enthusiasts or companies have undertaken the work of building effective/usable interfaces.

I can't really help you with the other questions, but I'm sure you'll get some more relevant responses.

Have fun using your 645 and I hope you'll enjoy your stay here on Photrio!

Thank you!

fs999 · Dec 5, 2022

You can also find Pentacon Six lenses with an adapter for P645. I use the 30mm MC Arsat regularly. I have also the 200mm F3.5 Jupiter 36B.

benveniste · Dec 6, 2022

ashcorra said:
What lenses can I use with my Pentax 645? I know I can use the original Pentax lenses, I found a list of them online, and I got a couple of the zoom lenses. However, I am wondering if it is possible to venture outside of the specified Pentax 645 lenses? As in other brands, for example?

Also, my husband has some EF lenses that I would love to be able to use , is there such thing as an adapter for 645 to EF?

Any feedback would be appreciated, as I'm new to lenses. Thank you.

The adapters I know of for the Pentax 645 are:

Pentax 67 (Used with a 300mm f/4)
Pentacon 6 (owned, but no P6 lenses!)
Hasselblad V
Bronica GS-1

On the adapter, the 300mm f/4 works well in aperture priority and manual mode. I previously tried to Zeiss Jena lenses, and both of them arrived DOA with aperture issues. The only complaint I have about my Pentax 645 lenses is an unfair one -- I had hoped that the 135mm LS could function as a leaf shutter lens when adapted for using on a Nikon body. Alas, it can't.

John Koehrer · Dec 6, 2022

If really want to fiddle around, get ahold of a bellows and use LF lenses. That should
give you a variety of longer fl's with coverage. There may be some vignetting from the mount.

Years ago I did this 35mm & lf lenses for giggles. the ones I used were pretty soft but
not unpleasant. You can assume they were real cheapies.

Which lenses to use on Pentax 645 (also 3rd party lenses?)

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