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01-22-2016, 06:01 AM   #1
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New to Pentax DSLR - Screw mount adapter question?


I have several Pentax film cameras (Spotmatic, MX, etc.) and a ton of old Pentax lenses from a long time ago, and I recently have gotten the "bug" again, so I just bought a used K-r, mainly because I wanted to see if I could use the old lenses?

I know that there are mount adapters, but looking around, I am confused about which ones to get and which ones NOT to get. I've read some posts about people having problems where they couldn't get the adapters off after mounting them, and others where they couldn't get infinity, and I'd like to avoid both problems.

So can someone tell me what I should look for with adapters for the K-r... flanged vs. non-flanged, etc.?



01-22-2016, 06:21 AM   #2
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the best to get is the genuine Pentax M42 to K mount adapter; more problems are reported with knock-offs; you'll see threads where all of a sudden, you can't get the adapter off the camera body and have to resort to violence to remove it...
01-22-2016, 06:28 AM   #3
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Only the Takumar Spotmatic-era lenses will need an adapter. The rest will mount straight on. There's a
which shows exactly how to meter with the older lenses.

If I were you, I would spend the money necessary to get one of the genuine Pentax-branded adapters or a reasonable facsimile from the same era. It will be more expensive, but better in the long run. I think there are still a couple for sale in the forum marketplace right now; I can PM you the seller's name if you're having trouble finding them. Look for people selling M42 gear. The adapter is the same regardless of which Pentax bayonet-mount camera you are using - they introduced them almost as soon as they went from screw to bayonet mount back in the 70's and went on making them for some time (even after they dropped "Asahi" from the brand name), and provided the adapter itself is reliable, it makes no difference which camera you use it on.

If you're going to go aftermarket, make sure that you go for an adapter that is advertised as guaranteeing infinity focus. The adapters that need a special tool to get them off can be a problem; the older, "official" K mount adapters can have their retaining spring pulled in with a fingernail and easily rotated off. If you are in any doubt, try it out on your MX before mounting it on the DSLR - because the MX's mount structure doesn't have electrical contacts, there isn't anywhere near as much chance of doing damage if you find yourself struggling to take the adapter off. When you're comfortable with what you're doing, then try it on the DSLR.

The older Pentax K-mount camera manuals advocated threading the adapter onto the lens first and then mounting it as if it were a bayonet-mount lens. Make sure before you do this that you are able to get the adapter on and off your DSLR with ease.

Good luck.
01-22-2016, 07:11 AM   #4
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Sorry - I just wanted to make sure I'm using the correct terminology. All of the old lenses I have, and all of the Pentax cameras, use a screw mount. I'm pretty sure the Spotmatics I have do (screw mount). I'm not sure if the MX, which I got later (I was mostly using Spotmatics), is screw or bayonet mount? In any event, all of the LENSES I have are screw mount, I think. So, given that, is the Pentax branded M42-to-K mount adapter the best for the Pentax K-r? Any after-market ones that anyone can recommend specifically?

---------- Post added 01-22-16 at 07:15 AM ----------

AAHH! Googling, it looks like the MX is K-mount? Can someone confirm that?

Now that I find that, I vaguely remember that I may have some M42-to-K mount adapter that I might've bought back then to use the M42 lenses with the MX. I'll have to rummage around my library tonight.

If I DO have such an M42-to-K mount adapter, am I good-to-go to use that with the M42-lenses on K-r?

Also, does that mean that the lens I have on the MX will just work on the K-r, WITHOUT any adapter?


01-22-2016, 07:30 AM   #5
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Yes, the MX is K-mount. I know because I own one, and because I need the M42-K adapter to put Takumar lenses on it.

If you still have an M42-K adapter from your MX film days, that will be perfect. It should have "Pentax" or "Asahi Pentax" on it, or perhaps just "P/K", and it should mount and unmount from your MX with ease. Again, try it out on the MX first.

Older lenses that fit the MX without an adapter will go on ANY Pentax DSLR without an issue. If it's SMC Pentax, you're good to go right away. Anything with Takumar on it needs the adapter. If in doubt, take the lens, take one of the AF lenses from your K-r, and compare the mounts. If they look the same, you're good.
01-22-2016, 08:02 AM   #6
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Actually I didn't get any lens with the K-r... just the body. What mount is the "normal" lenses for the K-r (what are they called)? Are those just "K mount"?
01-22-2016, 08:10 AM   #8
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Pentax K-Mount Lenses Explained: The differences between various Pentax lens series

Pentax Lenses - Pentax Lens Reviews & Lens Database

The Pentax Camera Lens Compatibility Chart

Edit: Jinx

01-22-2016, 08:50 AM   #9
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The KALT adapter I have is as reliable as the genuine Pentax but it does require a tool. Mine was new old stock from eBay. I would suggest testing the adapter on the MX and getting comfortable with it before you mount to the digital camera.
01-22-2016, 09:16 AM   #10
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The K-r isn't the best dslr to use the legacy M42 lenses - exposures are way off. i wrote this piece about it:

I was much happier after upgrading to K5.
As a general rule all the pentax dslr's show some effect with a black non conducting lens mount. On my k5 the green button doesn't work - only a problem with the few 3rd party early K mount lenses and some TC's that were like this.
Just have to familiarise with these little idiosyncracies.

I use both original Japanese/OEM and cheap clone M42 adapters, I did have to take a fine file to a couple of rough edges on a couple of the cheap clones but otherwise no probs. I prefer to take off any clips and put the M42 adapter on the lens and mount it like a K lens. i use a bit of tape to "lock" the thread. Sometimes I find I need to shim the adapter a bit with a piece of tape otherwise it's too tight a fit.

Addendum: and mirrorless has significant advantages: accurate exposures (because always off the sensor), easy adaption (because of short registration distances), quick accurate focus with magnification/assist/peaking modes. I also have a Lumix G1 and a samsung NX20, both have very good evf (I wouldn't get one without) as well as fully articulating screen. But I have to say overall I prefer the results off my K5!!

Last edited by marcusBMG; 01-22-2016 at 12:51 PM. Reason: pic
01-22-2016, 09:32 AM   #11
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Thanks I'll look at that. I just grabbed the K-r because I've been wanting to try my old lenses with a DSLR for a long time, and finally got around to it and found a auction on Ebay ... I actually thought about a mirrorless, and had considered one of the 'Q' series but I wanted a viewfinder, so that led me to DSLR.
01-22-2016, 09:51 AM   #12
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I much prefer an A7 with old Pentax lenses over my K5. I use a direct M42 to E adapter for Super Takumar, and a Voigtlander PK to E for my K and M lenses.
01-22-2016, 11:20 AM   #13
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I think I found it:

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01-22-2016, 12:58 PM   #14
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Yep. That's the one. You're good to go.
01-22-2016, 01:00 PM   #15
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Thanks. Now, all I gotta do is to wait for the camera to arrive !!

---------- Post added 01-22-16 at 01:24 PM ----------

Ok, I just put the adapter on the MX and was able to take it off without any "drama".

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