[espanola]

I know only M42 lens can be mounted to Pentax with M42-K adapter.
The list may be more, or somebody can mod lens to use with K-mount without an adapter.

Please contribute so that we can extend the range of lens for pentaxian:
1. M42 with M42-K mount
2.

[Marc Sabatella]

That's basically it for lenses that work perfectly with commercially available adapters. some Nikon lenses with fit (sort of) with no adapter - see the current thread on that topic. But for all others, the only possible adapters would degrade IQ, change the focal length, lose infinity focus, or all three.

[RioRico]

That's basically it for lenses that work perfectly with commercially available adapters. some Nikon lenses with fit (sort of) with no adapter - see the current thread on that topic. But for all others, the only possible adapters would degrade IQ, change the focal length, lose infinity focus, or all three.

Close, Marc, but not quite. Soviet M39 (NOT Leica Thread Mount or L39) lenses can be easily and cheaply fitted with M39-->M42-->PK adapters. The trick is to determine whether the lens is M39 or L39 *before* paying for it. I've kissed many frogs to find that princess, I'll tell ya.

And as you know, what limits cross-brand lens usage is the REGISTER, the lens-to-sensor working distance. Camera Mounts Sorted by Register lists these for many brands. Those with registers greater than the Praktica/Pentax 45.46mm COULD be mounted, but except for press-fitting a Nikon F-mount, most with registers under 50mm (such as Contax/Yashica, Petri, Ricoh, Olympus OM, Leica R, etc) are probably impractical to adapt. (They MUST be impractical, because I've never seen such adapters. Successful lens surgery would require exquisite machining.) Canon, Minolta, Miranda, Sony, Konica, other Leica and Olympus, are just plain impossible without the degradations you mention. Why use a Mercedes lens that's degraded down to Trabant quality?

[EXCEPTION: Almost any lens can be rigged somehow for macro work. But just how many macro lenses does one need?]

Medium-format lenses are a different story. We've seen commercial PK adapters for various 645 and 6x6 etc lenses, sometimes even shift-tilt adapters. None of those are cheap, or small. Someone with a batch of Hassy or Bronica glass might want such an adapter for their Pentax SLR, but otherwise, the economics suck.

[EXCEPTION: I've forced medium- and large-format lenses into a short PK macro tube and mounted them on bellows. Ugh.]

[deadwolfbones]

M39 lenses will lose infinity focus when used with a M39>M42>P/K adapter chain, though.

[RioRico]

M39 lenses will lose infinity focus when used with a M39>M42>P/K adapter chain, though.

Mine haven't, not when used with an infinity-focus (non-flanged) M42-PK adapter. The M39-M42 is just a thin double-threaded ring that doesn't change lens distance.

[GeneV]

And as you know, what limits cross-brand lens usage is the REGISTER, the lens-to-sensor working distance. Camera Mounts Sorted by Register lists these for many brands. Those with registers greater than the Praktica/Pentax 45.46mm COULD be mounted, but except for press-fitting a Nikon F-mount, most with registers under 50mm (such as Contax/Yashica, Petri, Ricoh, Olympus OM, Leica R, etc) are probably impractical to adapt. (They MUST be impractical, because I've never seen such adapters. Successful lens surgery would require exquisite machining.)

This place claims to adapt Contax for PK mounts. Leica & Pentax & Nikon | Leitax

[deadwolfbones]

Mine haven't, not when used with an infinity-focus (non-flanged) M42-PK adapter. The M39-M42 is just a thin double-threaded ring that doesn't change lens distance.

Aha, right you are: https://www.pentaxforums.com/forums/584175-post2.html



However, I do seem to recall someone trying to sell me a M39 Helios-40 and stating that it would not focus to infinity with his M39->M42->P/K adapter chain. Hmm...

[Lowell Goudge]

I have an optically corrected Nikon FI to PK mount.

I found it on Ebay reciently and posted a review on it.

it is essentually a 1.25 x Teleconverter.

Unless you have optical correction in an adaptor, you will not get a lens to work because except fro screw mount lenses, the other bayonette mount lenses need an adaptor with significant space between mounts to fit into the pentax mount, this screws up regestration distance and infinity focus.

once you get optical correction this is overcome, but yyou have the 1/2 stop and increased focal length, which really make adaptors useful on fast telephotos, especially when you conisder you are already giving up field of view with the ASP-C crop factor

[xjjohnno]

Dead wolfbones, the Zenit M39 mount has the same registry distance as the M42 and PK mounts. My Helios 40 adapted from M39 works fine re infinity focus. A pity my M39 Tair 11A doesn't.

[deadwolfbones]

Dead wolfbones, the Zenit M39 mount has the same registry distance as the M42 and PK mounts. My Helios 40 adapted from M39 works fine re infinity focus. A pity my M39 Tair 11A doesn't.

Hmm!

Maybe I'll have to look that guy up again.

[newarts]

For lenses with registry distance greater than 45.46mm it is usually not difficult to remove the OEM bayonet & replace it with a properly shimmed, flange type m42-PK adapter. This usually requires disabling the lens' auto-aperture lever.

I have done this with Nikon and OM lenses.

Lenses with shorter registry distance can often be converted; usually with more difficulty because the lens must be shortened somehow (Canon FD for example.)

Third-party lenses like Sigma, Tamron, etc, are often easy to convert because the manufacturer builds that capability into the lens for their convenience in making the same lens for different mounts.

[RioRico]

This place claims to adapt Contax for PK mounts. Leica & Pentax & Nikon | Leitax

I stand corrected -- and I should have remembered that I could *almost* force-fit a Contax-Yashica lens onto a PK mount. These Leitax mounts require only minor surgery (or pay Eu50 do have them do it). But at Eu58-75 per mount, plus Eu10 shipping, plus Eu5 per tool, plus other incidentals as needed, only rather valuable lenses would be worth converting. [Let's see, Dollar-Euro conversion rate today is just over US$1.35, so they run a minimum of US$92-115 each.] Still, if one has a bunch of Leica-R lenses without a body, it's probably most cost-effective to convert them -- if you don't mind manual aperture only. [bitch whine moan]

I have an optically corrected Nikon FI to PK mount. I found it on Ebay reciently and posted a review on it. it is essentually a 1.25 x Teleconverter.

Unfortunately, such "optical correction" all too often degrades IQ enough that the lens is no longer so special. I'd rather not convert my Nikkor into a Porst.

[MattGunn]

...most with registers under 50mm (such as Contax/Yashica, Petri, Ricoh, Olympus OM, Leica R, etc) are probably impractical to adapt. (They MUST be impractical, because I've never seen such adapters. Successful lens surgery would require exquisite machining.) Canon, Minolta, Miranda, Sony, Konica, other Leica and Olympus, are just plain impossible without the degradations you mention...

OM lenses are quite easy to convert even if there isn't a commercial adapter / conversion as with Laitax and the machining tolerences are not that tight, have alook at this thread: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/34323-zuiko-lens-club.html . Many of the "just plain impossible" lenses have been sucessfully converted too without losing infinity focus, see here: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/64271-impossible-lens-club.html With enough motivation and patience most lenses can be made to work.

[RioRico]

OM lenses are quite easy to convert even if there isn't a commercial adapter / conversion as with Laitax and the machining tolerences are not that tight, have alook at this thread: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/34323-zuiko-lens-club.html . Many of the "just plain impossible" lenses have been sucessfully converted too without losing infinity focus, see here: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/64271-impossible-lens-club.html With enough motivation and patience most lenses can be made to work.

As impossible, I meant other Oly lenses, like for the Pen-F series, not the OMs, which are impractical for mere mortals like me (lacking the right tools and skill). By impossible, I meant with usage of any add-on adapter. Sure, almost any lens can be fitted to almost any mount, given enough surgery. I *could* take a Leica LTM lens, hacksaw the tube, stick it in a PK extension base, carefully bonded with Liquid Metal or something, or just mount it on bellows -- but it would be ugly. Gruesome. Grotesque. Hey, it sounds better all the time!