M42 to K mount

Jobs · 09-08-2006, 01:47 PM

I'm planning on jumping on the Pentax SLR bandwagon, but had a question about using M42 scrwe mounts on the K. I assume that the official Pentax adaptor is no different than most generics, and that all I need to do to make the SR effective is to input the focal length of the lens.

I'm just curious, since I can't seem to locate an official adaptor, and saw one the other day for $10. If that will do the trick, that really expands the possabilities...

regken · 09-08-2006, 02:01 PM

Am running into the same thing. The Pentax adapter is hard to find. I read a couple of threads that some of the generic adapters cause problems so I kept looking for the real thing by calling KEH. $38, price is high but I have a little better feeling about it.

Ken

Rufus T. Firefly · 09-08-2006, 03:58 PM

I got mine from Adorama. Click Here It's the official Pentax one for $21.50 plus shipping. The off-brand ones may not sit flush with the camera body and cause the lens to not focus to infinity. Some do work but I can't tell you which ones will.

roy · 09-08-2006, 04:42 PM

ditto on what rufus said. if you get one off ebay, be sure to ask the seller if you lose infinity focus. if they say yes or ''i don't know'' walk away. best to get it at adorama. that way it's sure thing...

Adam · 09-08-2006, 05:01 PM

I believe you can also get the adapter directly from pentax- I got one last year

Here's a copy of the manual in case you're interested in that:

carpents · 09-08-2006, 05:57 PM

Originally posted by Jobs

I'm planning on jumping on the Pentax SLR bandwagon, but had a question about using M42 scrwe mounts on the K. I assume that the official Pentax adaptor is no different than most generics, and that all I need to do to make the SR effective is to input the focal length of the lens.

I'm just curious, since I can't seem to locate an official adaptor, and saw one the other day for $10. If that will do the trick, that really expands the possabilities...

I have a Kalt brand (from B&H) and another 'generic' brand that both work fine with most of my lenses. The real Pentax adapters work better with my 300/4 (very heavy) and my Russian lenses (not built to the same tolerances as the Asahi Takumars).

For $10, why not? As a side note - I removed the little locking pin in mine and keep them on the lens, effectively using them as a bayonet lens. This didn't work on my Jupiter-9 however because there wasn't sufficient friction on the base of the lens to keep it in place. On that lens I made a notch with a rotary tool aligned with the locking pin on the camera so now it clicks into place - no problems!

--Sean

shades · 09-08-2006, 06:04 PM

Some find it easier to screw the adapter onto the lens first, then bayonet the whole thing onto the camera.

When detaching it you need to unscrew the lens first, then remove the adapter as per the instructions.

Rupert · 09-08-2006, 06:57 PM

Get the genuine Pentax adapter, it is not much more but it is much better and easier to use. I learned the hard way, you don't have to.

Rufus T. Firefly · 09-08-2006, 06:58 PM

Originally posted by shades

Some find it easier to screw the adapter onto the lens first, then bayonet the whole thing onto the camera.

When detaching it you need to unscrew the lens first, then remove the adapter as per the instructions.

I followed the instructions at first placing the adapter into the camera and then screwing on the lens. But the aperture markings and distance scale were off to the side. Of course it didn't effect the operation; just looked odd. If I screw the adapter on first and then insert it lines up with markings on top.

JCSullivan · 09-09-2006, 05:10 AM

Some third party adapters are cheaply made so be on the lookout. Also, if you're going to use it with a M42 bellows be ready for a difficult time because the flash housing on top of the camera (istD) juts-out causing interference.

cmv · 09-12-2006, 09:09 PM

http://www.pentaximaging.com/purchase/

Click on: Purchase Our Products -> Shop Online -> Teleconverters/Mount Adapters (under SLR Accessories)

You want "Mount Adapter B" which appears to be $30. If anyone orders please share the shipping cost and how long it takes to get to you. I'm thinking of picking one up soon.

edit: Adorama deal sounds better though! But visit the Pentax site. It is interesting to see what they have listed in the online store.

tswill2 · 09-20-2006, 12:12 PM

If you are taking macro anyway, you could space the bellows out with a 1 cm extension tube.

tswill2 · 09-20-2006, 12:18 PM

Both the M42 and the K bayonet use the same flange distance. that is the distance from the face of the flange to the "film" (or digital sensor).
Pentax K 35 mm still Bayonet 45.46 mm
M42 lens mount 35 mm still Screw (42 mm×1mm) 45.46 mm

Therefore ANY flange on a screw adapter is going to shift the focus in from infinity. If you stop down, hyperfocal DOF will effectively negate the difference.

Ole · 09-20-2006, 02:54 PM

The Pentax M42 screw mount to K adapter is sitting flush with the face of the bayonet mount so screw mount lenses focus all the way to infinity.

HogRider · 09-20-2006, 03:34 PM

If you are brave, you can do the following: Buy a few cheap M42 to K mount converters. The flush sitting ones, but no need to buy the expensive ones. Then remove the little leaf spring and mount them permanently onto a Screw mount lens. (No glue needed - just screw them on REALLY tight)

Here is a PDF file that explains exactly what do to. Save it to your PC in case the site goes away one day. It might come in hand, in the future.

http://www.rit.edu/~andpph/photoforum/pdf/lens_conv.pdf

You can modify the lens so it "clicks' and sits tight on the camera. Basically it turns into a K mount lens, but without the automatic aperture function.

I have done this successfully with multiple lenses. Never had a problem. Only important thing is, that you take your time and also tape off the rest of the lens, so little metal dust and filings cannot get inside the lens.

09-08-2006, 01:47 PM	#1
Jobs New Member Join Date: Sep 2006 Posts: 6	M42 to K mount I'm planning on jumping on the Pentax SLR bandwagon, but had a question about using M42 scrwe mounts on the K. I assume that the official Pentax adaptor is no different than most generics, and that all I need to do to make the SR effective is to input the focal length of the lens. I'm just curious, since I can't seem to locate an official adaptor, and saw one the other day for $10. If that will do the trick, that really expands the possabilities...

09-08-2006, 05:01 PM	#5
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	I believe you can also get the adapter directly from pentax- I got one last year Here's a copy of the manual in case you're interested in that: Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

09-08-2006, 05:57 PM	#6
carpents Veteran Member Join Date: Sep 2006 Location: West Chester, PA Photos: Gallery \| Albums Posts: 1,420	It Probably Works, Though Originally posted by Jobs I'm planning on jumping on the Pentax SLR bandwagon, but had a question about using M42 scrwe mounts on the K. I assume that the official Pentax adaptor is no different than most generics, and that all I need to do to make the SR effective is to input the focal length of the lens. I'm just curious, since I can't seem to locate an official adaptor, and saw one the other day for $10. If that will do the trick, that really expands the possabilities... I have a Kalt brand (from B&H) and another 'generic' brand that both work fine with most of my lenses. The real Pentax adapters work better with my 300/4 (very heavy) and my Russian lenses (not built to the same tolerances as the Asahi Takumars). For $10, why not? As a side note - I removed the little locking pin in mine and keep them on the lens, effectively using them as a bayonet lens. This didn't work on my Jupiter-9 however because there wasn't sufficient friction on the base of the lens to keep it in place. On that lens I made a notch with a rotary tool aligned with the locking pin on the camera so now it clicks into place - no problems! --Sean

09-08-2006, 06:57 PM	#8
Rupert Veteran Member Join Date: Sep 2006 Location: Texas Photos: Gallery \| Albums Posts: 25,123	Save yourself frustration Get the genuine Pentax adapter, it is not much more but it is much better and easier to use. I learned the hard way, you don't have to.

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09-08-2006, 02:01 PM	#2
regken Veteran Member Join Date: Sep 2006 Location: Bangor, Maine Photos: Gallery Posts: 1,377	Am running into the same thing. The Pentax adapter is hard to find. I read a couple of threads that some of the generic adapters cause problems so I kept looking for the real thing by calling KEH. $38, price is high but I have a little better feeling about it. Ken

09-08-2006, 03:58 PM	#3
Rufus T. Firefly Junior Member Join Date: Sep 2006 Location: Marshfield MA. Posts: 35	I got mine from Adorama. Click Here It's the official Pentax one for $21.50 plus shipping. The off-brand ones may not sit flush with the camera body and cause the lens to not focus to infinity. Some do work but I can't tell you which ones will.

09-08-2006, 04:42 PM	#4
roy Inactive Account Join Date: Sep 2006 Location: D/FW area, Tx. Photos: Gallery Posts: 1,710	ditto on what rufus said. if you get one off ebay, be sure to ask the seller if you lose infinity focus. if they say yes or ''i don't know'' walk away. best to get it at adorama. that way it's sure thing...

09-08-2006, 06:04 PM	#7
shades Inactive Account Join Date: Sep 2006 Posts: 17	Some find it easier to screw the adapter onto the lens first, then bayonet the whole thing onto the camera. When detaching it you need to unscrew the lens first, then remove the adapter as per the instructions.

09-08-2006, 06:58 PM	#9
Rufus T. Firefly Junior Member Join Date: Sep 2006 Location: Marshfield MA. Posts: 35	Originally posted by shades Some find it easier to screw the adapter onto the lens first, then bayonet the whole thing onto the camera. When detaching it you need to unscrew the lens first, then remove the adapter as per the instructions. I followed the instructions at first placing the adapter into the camera and then screwing on the lens. But the aperture markings and distance scale were off to the side. Of course it didn't effect the operation; just looked odd. If I screw the adapter on first and then insert it lines up with markings on top.

09-09-2006, 05:10 AM	#10
JCSullivan Veteran Member Join Date: Sep 2006 Location: Windsor, Canada Posts: 3,056	Some third party adapters are cheaply made so be on the lookout. Also, if you're going to use it with a M42 bellows be ready for a difficult time because the flash housing on top of the camera (istD) juts-out causing interference.

09-12-2006, 09:09 PM	#11
cmv Senior Member Join Date: Sep 2006 Location: Chicago, IL, USA Posts: 147	http://www.pentaximaging.com/purchase/ Click on: Purchase Our Products -> Shop Online -> Teleconverters/Mount Adapters (under SLR Accessories) You want "Mount Adapter B" which appears to be $30. If anyone orders please share the shipping cost and how long it takes to get to you. I'm thinking of picking one up soon. edit: Adorama deal sounds better though! But visit the Pentax site. It is interesting to see what they have listed in the online store.

09-20-2006, 12:12 PM	#12
tswill2 Junior Member Join Date: Sep 2006 Location: Ocala,FL&Boonville,NY Posts: 31	If you are taking macro anyway, you could space the bellows out with a 1 cm extension tube.

09-20-2006, 12:18 PM	#13
tswill2 Junior Member Join Date: Sep 2006 Location: Ocala,FL&Boonville,NY Posts: 31	Both the M42 and the K bayonet use the same flange distance. that is the distance from the face of the flange to the "film" (or digital sensor). Pentax K 35 mm still Bayonet 45.46 mm M42 lens mount 35 mm still Screw (42 mm×1mm) 45.46 mm Therefore ANY flange on a screw adapter is going to shift the focus in from infinity. If you stop down, hyperfocal DOF will effectively negate the difference.

09-20-2006, 02:54 PM	#14
Ole Administrator Join Date: Sep 2006 Location: Copenhagen, Denmark Photos: Gallery \| Albums Posts: 4,408	The Pentax M42 screw mount to K adapter is sitting flush with the face of the bayonet mount so screw mount lenses focus all the way to infinity.

09-20-2006, 03:34 PM	#15
HogRider Veteran Member Join Date: Sep 2006 Location: Arizona, USA Photos: Gallery Posts: 608	If you are brave, you can do the following: Buy a few cheap M42 to K mount converters. The flush sitting ones, but no need to buy the expensive ones. Then remove the little leaf spring and mount them permanently onto a Screw mount lens. (No glue needed - just screw them on REALLY tight) Here is a PDF file that explains exactly what do to. Save it to your PC in case the site goes away one day. It might come in hand, in the future. http://www.rit.edu/~andpph/photoforum/pdf/lens_conv.pdf You can modify the lens so it "clicks' and sits tight on the camera. Basically it turns into a K mount lens, but without the automatic aperture function. I have done this successfully with multiple lenses. Never had a problem. Only important thing is, that you take your time and also tape off the rest of the lens, so little metal dust and filings cannot get inside the lens.