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M42 adapter for Pentax LX
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PostPosted: Mon Jun 20, 2016 10:37 am    Post subject: M42 adapter for Pentax LX Reply with quote

Hello firends!

I am pretty excited as I have aquired a Pentax LX body. However, nearly all the lenses I intend to use on it are M42. I assume I get a high quality Pentax K to M42 adapter that I install indide the camera mount to accomodate this?

If so, can somebody point me at a preferred type? Are there any downsides in terms of metering or other practical issues when I use M42 lenses on a LX body?

Thanks for any advice Smile


EDIT:

Also, does using this adapter mean I can't use lenses in auto mode? No open lens metering?


PostPosted: Mon Jun 20, 2016 5:42 pm    Post subject: Reply with quote

Any flangeless M42-PK adapter should do. If you want to be absolutely careful get the Pentax brand ones though I haven't seen any difference. Not to say of course that some random brand may have some problem.

I have put M42 lenses on my LX but I cant say I've actually shot anything that way.

Stop down metering and stop down shooting are your only options, much like putting M42 lenses on a DSLR.


PostPosted: Mon Jun 20, 2016 6:56 pm    Post subject: Reply with quote

The Asahi Pentax M42 Super-Multi-Coated lenses have aperture coupling to M42 camera body -- if M42-K adapted S-M-C lens aperture coupling works with K-mount body -- anybody know? -- then open aperture metering should be possible, however, to make a photo will still require manual stop down mode where you set lens aperture and shutter speed.


PostPosted: Mon Jun 20, 2016 8:28 pm    Post subject: Reply with quote

" if M42-K adapted S-M-C lens aperture coupling works with K-mount body -- anybody know? "

I have never heard of such an adapter. The official M42-PK adapter from Pentax is a simple mount adapter ring, as are all the copies that I have seen.

An adapter to convert the linear pin to the vertical lever on PK would be complex and I don't see how such a thing could fit in a PK camera.


PostPosted: Mon Jun 20, 2016 8:39 pm    Post subject: Reply with quote

Ok thats cool, I don't really mind stop down metering. Smile
I have so many cameras that I sometimes confuse myself though, hence double checking.

I will try a cheapo adapter first as the genuine pentax ones are really rather expensive!


PostPosted: Tue Jun 21, 2016 4:44 pm    Post subject: Reply with quote

luisalegria wrote:
" if M42-K adapted S-M-C lens aperture coupling works with K-mount body -- anybody know? "

I have never heard of such an adapter. The official M42-PK adapter from Pentax is a simple mount adapter ring, as are all the copies that I have seen.

An adapter to convert the linear pin to the vertical lever on PK would be complex and I don't see how such a thing could fit in a PK camera.


A misunderstanding. Wink The aperture coupling is a lever that moves radially as the aperture ring is turned. PK lenses appear to have the same lever. Of course the aperture pin of M42 lenses cannot be depressed by K-mount camera body! Laughing That is why I added the sentence about having to utilize camera's stop down manual mode to make the photo, even if the aperture coupling does work. If the Pentax M42 aperture coupling LEVER does work with K-mount body, then the camera should be able to meter wide open -- again, to make a photo, however, the camera lens must be manually stopped down...


PostPosted: Tue Jun 21, 2016 11:37 pm    Post subject: Reply with quote

I have the Pentax brand adapter ring and, as Luis states, it is just an adapter. It doesn't interface with the lens's aperture control at all. Stop-down metering is no big deal though.


PostPosted: Wed Jun 22, 2016 2:54 am    Post subject: Reply with quote

cooltouch wrote:
I have the Pentax brand adapter ring and, as Luis states, it is just an adapter. It doesn't interface with the lens's aperture control at all. Stop-down metering is no big deal though.


Right, the simple adapter only adds "fins" to the M42 screw mount.

On this PK lens, the aperture coupling lever is seen in the slot on the left side:



With M42-PK adapter attached does this same lever on Pentax M42 S-M-C lens couple to the PK body, just like a PK mount lens aperture coupling lever?


PostPosted: Wed Jun 22, 2016 3:39 pm    Post subject: Reply with quote

I recommend getting an original Pentax adapter - from my personal experience they feature significantly higher level of workmanship.

There will be no open aperture metering - it is done in drastically different way on M42 and K bodies.


PostPosted: Wed Jun 22, 2016 3:48 pm    Post subject: Reply with quote

Gardener wrote:
I recommend getting an original Pentax adapter - from my personal experience they feature significantly higher level of workmanship.

There will be no open aperture metering - it is done in drastically different way on M42 and K bodies.


A very generous forum member is going to donate one to me, so it seems I am covered!
Smile

Can't wait to put it all together and go on a photography spree!


PostPosted: Fri Jun 24, 2016 2:38 am    Post subject: Reply with quote

Gardener wrote:
I recommend getting an original Pentax adapter - from my personal experience they feature significantly higher level of workmanship.

There will be no open aperture metering - it is done in drastically different way on M42 and K bodies.


I'm not sure what you mean by "done in drastically different way".

The coupling of the lens aperture ring setting to the camera body is similar on both types of lenses. Both use a lever moving in an arch. However, the lever position is different -- with M42 the lever is inside the M42 threads; with PK, the lever is outside the mount fins. So yes, "there will no open aperture metering of S-M-C M42 lens adapted onto PK mount camera".


PostPosted: Fri Jun 24, 2016 3:43 pm    Post subject: Reply with quote

visualopsins wrote:
I'm not sure what you mean


The part where the camera needs to close the aperture to obtain correct exposure.


PostPosted: Fri Jun 24, 2016 8:39 pm    Post subject: Reply with quote

Gardener wrote:
visualopsins wrote:
I'm not sure what you mean


The part where the camera needs to close the aperture to obtain correct exposure.


Right, that's why I said to make the photo still requires manual stop down of lens and setting of shutter speed. If the lever had coupled, however, there is no reason why the camera could not meter properly with lens wide open.


PostPosted: Fri Jul 08, 2016 8:41 am    Post subject: Reply with quote

Hello! Yes, normally, you lose the ability to use autofocus on those lenses, but with them, you can make excellent photos. As for the adapter for the M42, I use the most simple one. I got it together with Helios (http://helios44-2.com) and 58mm f/2. This adapter totally satisfies me, and I do not have any discomfort. Sometimes, the lens spins a little relatively to the camera, but it's not a big problem. Good luck!


PostPosted: Fri May 12, 2017 1:28 am    Post subject: Reply with quote

visualopsins wrote:
Gardener wrote:
visualopsins wrote:
I'm not sure what you mean


The part where the camera needs to close the aperture to obtain correct exposure.


Right, that's why I said to make the photo still requires manual stop down of lens and setting of shutter speed. If the lever had coupled, however, there is no reason why the camera could not meter properly with lens wide open.


The levers are in the wrong locations relative to each other (K mount left side, M42 above) and to the radial distance from the lens axis, and can never engage each other. Also their degree of movement per stop closed down is different.


PostPosted: Wed Jan 10, 2018 9:09 pm    Post subject: Reply with quote

Bit of an old post but...

Using M42 lenses on the LX is great. Leave the camera on Av, the switch on the lens to manual. Focus wide open. Shut down aperture to required value, then shoot. It is actually much easier to use M42 lenses on more modern Pentax cameras (i.e., the so-called crippled K-mount, including digital) than it is to use the K and M series lenses where you have to use manual and the green button to meter.

K.