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04-16-2009, 09:05 PM   #1
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An Adaptall to M42 adapter modification

I just received a Tamron 24mm 2.5 that was fitted with an Adaptall to M42 adapter. I knew beforehand that I need to “fix” the pin in the base of the adapter to allow using the aperture ring; otherwise the aperture will always remain wide open when mounted on my K10d. This M42 adapter is a good alternative to the P/KA (full auto but expensive) or the PK (manual mode). It is semi-auto with Av mode & stop down metering. And I think it might even cost less than the PK adapter.
The Mod is easy and is the same idea as the other M42 lenses conversion.

Unscrew the three screws on the base of the adapter and removed the pin.


Wrap a short section of plastic wire isolation to keep the pin permanently depressed.


Re-install the pin to the base of the adapter.





04-16-2009, 09:40 PM   #2
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I too have an Adaptall-2 M42 mount and have considered doing the same fix. My only problem is that I sometimes use the mount on my screwmount cameras!

Steve

BTW...That is one CLEAN looking 24/2.5...at least the side in your picture is clean...
04-16-2009, 09:58 PM   #3
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QuoteOriginally posted by stevebrot Quote
I too have an Adaptall-2 M42 mount and have considered doing the same fix. My only problem is that I sometimes use the mount on my screwmount cameras!

Steve

BTW...That is one CLEAN looking 24/2.5...at least the side in your picture is clean...
I am just glad that I have an option other than the PKA. The lens overall condition is excellent.

04-16-2009, 09:59 PM   #4
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Now that is a nice looking lens (wipes drool from mouth and chin)...

Steve

04-17-2009, 07:27 AM   #5
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A nice contribution to this topic.

An alternative that doesn't require disassembling the lens is to us a fitted length of insulation stripped from #10~12 electrical wiring. Split it down the length and you can slip it over the pin with a little fiddling. A small drop of something "sort 'a sticky" inside the insulation makes this a semi-permanent mod that COULD be removed if necessary (requires disassembly to clean the pin) but ensures the spacer won't slip off the pin.

H2
04-17-2009, 07:40 AM   #6
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QuoteOriginally posted by IS050 Quote
I am just glad that I have an option other than the PKA. The lens overall condition is excellent.

curious question on the lens. My copy, (bought in 1982) has developed som backlash (play) in the focusing collar. How does your copy behave?
04-17-2009, 09:12 AM   #7
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QuoteOriginally posted by Lowell Goudge Quote
curious question on the lens. My copy, (bought in 1982) has developed som backlash (play) in the focusing collar. How does your copy behave?
Lowell, The focus on mine copy is very smooth, did not have the backlash you mentioned. Both in and out of the lens are clean and function as it should.

QuoteOriginally posted by pacerr Quote
A nice contribution to this topic.
H2
Hi Pacerr, this is a good idea, thanks for sharing.
04-19-2009, 02:10 AM   #8
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Hi IS050

I've come across your post and because I've an Tamron Tele-Converter 2X Pentax M42 that I would like to use with the Tamron SP 90mm, I'm thinking about buying an M42 to PK adapter and "fix" the converter as you did with the M42 mount; You stated that this fix will act as "a semi-auto with Av mode & stop down metering" but I'm a bit confused about the meaning of your words; could please explain if I wil be able to auto meter and adjust the aperture in the camera (like in an PKA mount)?

Thanks in advance,

MB


Last edited by Manel Brand; 04-19-2009 at 02:12 AM. Reason: clarity of arguments
04-19-2009, 05:05 PM   #9
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QuoteOriginally posted by Manel Brand Quote
Hi IS050

I've come across your post and because I've an Tamron Tele-Converter 2X Pentax M42 that I would like to use with the Tamron SP 90mm, I'm thinking about buying an M42 to PK adapter and "fix" the converter as you did with the M42 mount; You stated that this fix will act as "a semi-auto with Av mode & stop down metering" but I'm a bit confused about the meaning of your words; could please explain if I wil be able to auto meter and adjust the aperture in the camera (like in an PKA mount)?

Thanks in advance,

MB
MB, it seems like you will need two adapters. An Adaptall to M42 (for the "fix") and M42 to K adapter. The semi-auto means that you manually stop the lens down (on the lens itself) and the Av mode will calculate shutter speed, so the camera is semi-auto metering base on the aperture your select and adjust the shutter speed. I could be incorrectly describe this as Semi-Auto but this is how it work after the modification of the adapter. Hope this help.

David
04-20-2009, 11:26 AM   #10
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QuoteOriginally posted by IS050 Quote
MB, it seems like you will need two adapters. An Adaptall to M42 (for the "fix") and M42 to K adapter. The semi-auto means that you manually stop the lens down (on the lens itself) and the Av mode will calculate shutter speed, so the camera is semi-auto metering base on the aperture your select and adjust the shutter speed. I could be incorrectly describe this as Semi-Auto but this is how it work after the modification of the adapter. Hope this help.

David
Hi David

Thank you for your answers.

Yes, you are right about the Adaptall to M42 and I believe I got one that could be used for that matter; not absolutely sure because it says "for Fujica" but I think it's an M42 adaptall mount; however, I was thinking about doing "the fix" on the converter and leave the minolta mount alone, as it seems more difficult to disassemble and could be used later with an M42 to PK adapter (if I'm lucky enough to find more bargain Tamron gems); in fact, I can't see any screws at all on the mount, but the converter it's pretty straightforward; it has 3 screws (like yours) that, if removed, give me full access to the "pin to fix".

If you don't mind, I would like to ask you to take a look at some photos of the mount and the converter and ask for your advice on how to fix them, the way you have suggested on your first post.

Hoping to hearing from you soon,

Manuel

Last edited by Manel Brand; 04-20-2009 at 12:41 PM. Reason: Correction of terms
04-20-2009, 12:58 PM   #11
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QuoteOriginally posted by Manel Brand Quote
Hi David

Thank you for your answers.

Yes, you are right about the Adaptall to M42 and I believe I got one that could be used for that matter; not absolutely sure because it says "for Fujica" but I think it's an M42 adaptall mount; however, I was thinking about doing "the fix" on the converter and leave the minolta mount alone, as it seems more difficult to disassemble and could be used later with an M42 to PK adapter (if I'm lucky enough to find more bargain Tamron gems); in fact, I can't see any screws at all on the mount, but the converter it's pretty straightforward; it has 3 screws (like yours) that, if removed, give me full access to the "pin to fix".

If you don't mind, I would like to ask you to take a look at some photos of the mount and the converter and ask for your advice on how to fix them, the way you have suggested on your first post.

Hoping to hearing from you soon,

Manuel
MB, I'm afraid I don't know hot to fix the minolta mount you have, the only advice I can offer is the fix of the Adaptall to M42 adapter on this posted. Perhaps someone who has that knowledge can help better than I do.

Thanks
David
04-20-2009, 02:10 PM   #12
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Ok David, thanks anyway; BTW, sorry about the confusion I've made; It's not "Minolta" but "Fujica" and I'm pretty sure now that's a M42 mount (Fujica as produced some lenses with the M42 mount and then shifted to Fujica X bayonet in 1980). As I've said, I want to fix the converter, not the adaptall mount, and the converter it's definitly a Pentax F M42 mount, just like yours M42 Adaptall. I will be posting some images of the converter; if someone want to take a look at them and make some considerations I would be grateful.

Thanks

MB

Last edited by Manel Brand; 04-20-2009 at 02:55 PM.
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