What is SM mount?

*gawan* · 07-17-2008, 05:41 PM

I read somewhere about a Pentax SM mount. Is this the same as M42 screw mount or something different?

garth1948 · 07-17-2008, 05:51 PM

Yes. You will need a Pentax screw to k mount adaptor,

*gawan* · 07-17-2008, 05:55 PM

Yes for being same or being different? That is, do I nee a M42 screw mount to K adapter?

Just wanted to know if there was a differing SM screw mount also, so not to make mistakes...

*Nesster* · 07-17-2008, 06:25 PM

Pentax screw = Pentax SM (Screw mount) = M42

They are all the same thing

*Blue* · 07-17-2008, 07:32 PM

Originally Posted by gawan

Yes for being same or being different? That is, do I nee a M42 screw mount to K adapter?

Just wanted to know if there was a differing SM screw mount also, so not to make mistakes...

Be aware though that there was a screw mount used by Pentax prior to the M42. It was called M37 and was used on Takumar lens from the early to mid 1950s.
Here is a history link> Early Pentax Takumar Lenses

While you probably won't encounter the m37 that often, its a good habit to refer to it as m42.

*gawan* · 07-18-2008, 02:31 AM

Thanks guys, I think I got it now

RioRico · 07-19-2008, 10:58 PM

Be careful with M42 (screw) -to-K- (bayonet) adapters. Some have a flange around the base of the adapter, which makes it easy to unmount from the camera, but it pushes the lens about 1mm further from the sensor or film plane. With many M42 lenses, you can no longer focus to infinity.

Other adapters, usually marketed as Infinity-Focus, lack that flange, but have a grumpy little spring to hold onto the camera body. These adapters DO allow the lens to seat and focus correctly. But you'll notice that each adapter is supplied with a thin steel 'key' for removal from the camera body. You may spend several infuriating minutes trying to remove the [expletive deleted] adapter.

I use both sorts. The flanged adapter mounts an old M42 bellows; or any M42 lens used with non-auto extension macro tubes; or any lens in a portrait session where I don't care about infinity. The flangeless [expletive deleted] adapter goes onto my K20D when I expect to use screwmount lenses all day.

Good luck.

*Mike Cash* · 07-19-2008, 11:29 PM

I must be blessed. I can pop my Roxsen adapter off with a fingernail in about two seconds with no tool and without looking at it. What on earth are you using that would necessitate the deletion of expletives?

stevebrot · 07-19-2008, 11:42 PM

Originally Posted by RioRico

Be careful with M42 (screw) -to-K- (bayonet) adapters. Some have a flange around the base of the adapter, which makes it easy to unmount from the camera, but it pushes the lens about 1mm further from the sensor or film plane. With many M42 lenses, you can no longer focus to infinity.

Other adapters, usually marketed as Infinity-Focus, lack that flange, but have a grumpy little spring to hold onto the camera body. These adapters DO allow the lens to seat and focus correctly. But you'll notice that each adapter is supplied with a thin steel 'key' for removal from the camera body. You may spend several infuriating minutes trying to remove the [expletive deleted] adapter.

I use both sorts. The flanged adapter mounts an old M42 bellows; or any M42 lens used with non-auto extension macro tubes; or any lens in a portrait session where I don't care about infinity. The flangeless [expletive deleted] adapter goes onto my K20D when I expect to use screwmount lenses all day.

Good luck.

One additional point regarding adapters...the authentic Pentax-brand adapter seats into the body, but does not require any tool more sophisticated than a fingernail to remove.

Another option is to semi-permanently attach an adapter onto your lens using a product such as Loktite. You must remove the retainer spring from the adapter first and then file a notch into the lens mount to engage the body's retaining pin. This technique works for any lens with a wide enough base to engage the retaining pin (my Jupiter-9 fails in this respect). You might also want to think twice before marring any lens that is potentially valuable as a collector's item. There are members of this forum that have done this modification and are very happy with the result.

Steve

ChrisN · 07-20-2008, 01:58 AM

Don't forget that Pentax also made a limited number of the 43 LTD lens with 39mm LTM (Leica Thread Mount) for the Leica rangefinder. I believe these were only sold in the Japanese market but a number have made their way overseas - very highly sought after, of course. See smc PENTAX L 43mm f/1.9 Special Chrome Leica L mount - eBay (item 180262225398 end time Aug-05-08 22:00:00 PDT)

*gawan* · 07-20-2008, 04:43 AM

Originally Posted by RioRico

Be careful with M42 (screw) -to-K- (bayonet) adapters. Some have a flange around the base of the adapter, which makes it easy to unmount from the camera, but it pushes the lens about 1mm further from the sensor or film plane. With many M42 lenses, you can no longer focus to infinity.

Other adapters, usually marketed as Infinity-Focus, lack that flange, but have a grumpy little spring to hold onto the camera body. These adapters DO allow the lens to seat and focus correctly. But you'll notice that each adapter is supplied with a thin steel 'key' for removal from the camera body. You may spend several infuriating minutes trying to remove the [expletive deleted] adapter.

I use both sorts. The flanged adapter mounts an old M42 bellows; or any M42 lens used with non-auto extension macro tubes; or any lens in a portrait session where I don't care about infinity. The flangeless [expletive deleted] adapter goes onto my K20D when I expect to use screwmount lenses all day.

Good luck.

I think I have the "flanged adapter", if you mean the kind with an wide plate colar? Also use it with a M42 bellows to camera. But I am actually also interested to find a lens to camera adapter, so it sems that I do need a different model in addition! Thanks for your clarification.

*Nesster* · 07-20-2008, 05:45 AM

Originally Posted by ChrisN

Don't forget that Pentax also made a limited number of the 43 LTD lens with 39mm LTM (Leica Thread Mount) for the Leica rangefinder. I believe these were only sold in the Japanese market but a number have made their way overseas - very highly sought after, of course. See smc PENTAX L 43mm f/1.9 Special Chrome Leica L mount - eBay (item 180262225398 end time Aug-05-08 22:00:00 PDT)

Now, if there was a mistaken delivery of a M39 43 as a M42, for a plain 43 price, I'd keep my mouth shut and lock all doors, bar all windows, before letting out a long bloodcurdling yowl: finally the universe has decided to smile in my back yard and I'm going to be RICH!

Then, I'd calmly mount it on my FED-3 and stroll around taking photos for a month or two.

*Blue* · 07-20-2008, 10:19 AM

Originally Posted by Nesster

Now, if there was a mistaken delivery of a M39 43 as a M42, for a plain 43 price, I'd keep my mouth shut and lock all doors, bar all windows, before letting out a long bloodcurdling yowl: finally the universe has decided to smile in my back yard and I'm going to be RICH!

Then, I'd calmly mount it on my FED-3 and stroll around taking photos for a month or two.

I here you.

RioRico · 07-22-2008, 03:37 PM

Originally Posted by Mike Cash

I must be blessed. I can pop my Roxsen adapter off with a fingernail in about two seconds with no tool and without looking at it. What on earth are you using that would necessitate the deletion of expletives?

I got some cheap Chinese M42-PK Infinity Focus adapters on eBay. I know nothing about Roxsen or other quality adapters. Thanks -- now I must search further.

At least one of those [expletive deleted] adapters has a safe home: on a Russian Rubinar 1000mm mirror. The lens body is too wide to fit onto the K20D lens mount, because of the camera's nameplate overhang. The endpieces (minus tubes) from a cheap macro tube set push the Rubinar out the requisite 11mm for clearance, and probably extend the lens's focal length to about 1100mm. The [expletive deleted] adapter is now permanently married to the macro mount, where it can cause no further frustration. Unless it breaks...

I'm sometimes too cheap for my own good. Sigh...

RioRico · 07-22-2008, 04:29 PM

Originally Posted by gawan

I think I have the "flanged adapter", if you mean the kind with an wide plate colar? Also use it with a M42 bellows to camera.

Yes, that's it.

But I am actually also interested to find a lens to camera adapter, so it sems that I do need a different model in addition! Thanks for your clarification.

A "lens to camera adapter" ?? Do you mean an adaptor that stays on the lens, rather than usually being on the camera?
__________________________________________________ _______________

Meanwhile, I have questions on using M39 lenses on my K20D.

I have a few M39 (Leica thread mount / LTM) lenses. Industar-61, Jupiter-9, Leitz Elmar 90/4 -- and some enlarger lenses to mount on my M42 bellows -- and a couple more Russian M39s are en route. And I have a few M39-M42 adapters. [WARNING: Buy those from China, not Ukraine or Russia, as the latter are absolute junk.] When I put the M39-M42 and M42-PK adapters on the Jupiter-9, I am happy, because the lens will focus to infinity. But when I mount the Industar-61 or the Leitz Elmar, I am most unhappy, because they become macro lenses.

Thanks to the "Camera Mounts Sorted by Register" page, I understand that with the Leica M39/LTM register of 28.8mm and the M42/PK register of 45.46mm, it's easy to mount Pentax lenses on Leica cameras, but not vice-versa, right? Except some Russian M39s, but not all of them, right? How can I tell which Russian M39s will work, or is that just a crapshoot? On the K20D Custom menu, 35. AF Adjustment, I changed the focusing position, but without luck. Maybe that only works with AF lenses, not this screw-mount stuff, eh?

So, the questions: 1) Has anybody here successfully mounted LTM lenses on a PK mount?
If so, 2) Did the fitting require hardware or software diddling, or both, or something else?
Or, 3) Since I don't plan to own/use a LTM film camera, should I just sell the LTM lenses?
HELP!!