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07-09-2010, 04:45 PM   #1
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Tamron Adaptall question

I'm picking up a Tamron SP lens to use on my *ist DS2, and I obviously need an adaptall mount to use with it. My question is, do I need a P/KA mount, or can I get away with a cheaper p/k? The price gap is huge, $20 for the pk, $100 for the pka. Thanks!

07-09-2010, 04:57 PM   #2
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The P/K adapter works fine though you must use it like an "M" lens. Stop down metering in M mode. I was lucky to get a couple PK/A for cheap a long time ago, before used pentax stuff went through the roof.
07-09-2010, 05:38 PM   #3
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Also consider getting the m42 mount since it will allow easier operation in Av mode than the P/K adapter would. That's assuming you have a m42 adapter like many of us do. However, the PK/A is great since it allows the A functions. Get you a P/K or m42 mount and be patient and you can get the PK/A cheaper. I saw one go recently for $89 BIN with a lens attached!
07-09-2010, 09:18 PM   #4
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Thanks guys! Don't know why I waited so long to join this forum

07-10-2010, 04:18 AM   #5
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Blue, only fly in the M42 adaptall (there's also an ES adaptall for the ES/F/ES-II cameras) is: no auto/manual switch. In order to use the M42 adaptall -> K adapter -> camera in any but wide open mode is to mess with the mount aperture pin.

(How do I know this so well? I wanted to do some macro, and so screwed in my 52bb 90mm macro onto the K100D, used flash, and then wondered why the spiders came out so over exposed and with no DOF )


Glacian, once you get over the manual exposure / stop down hurdle with digital, it really is not so bad: usually I just do one stop down reading and then simply adjust the shutter speed up or down as needed - and as chimped from the LCD on the camera. For me there was a psychological hurdle abandoning all the automation the camera provided, but once over it, it's fun and fast.

That said, if you do find a K-A adapter cheap, it's worth it. Like Blue says, sometimes they are 'hidden' mounted to a lens.
07-15-2010, 12:09 AM   #6
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QuoteOriginally posted by Blue Quote
Also consider getting the m42 mount since it will allow easier operation in Av mode than the P/K adapter would. That's assuming you have a m42 adapter like many of us do. However, the PK/A is great since it allows the A functions. Get you a P/K or m42 mount and be patient and you can get the PK/A cheaper. I saw one go recently for $89 BIN with a lens attached!
I am trying to figure out how AV mode would be easier with the m42 mount and m42 to K adapter versus Adaptall PK/M mount and I am unable to do so (I don't have m42 mount). Please explain.

Thanks,
07-15-2010, 06:15 AM   #7
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Av is not available with K-M mount lenses, you have to use manual metering. Or rather, Av will only work wide open, as there's no communication between aperture set on lens and the camera body.
Av works with screw mount lenses if you are able to set the lens on M/manual aperture - that is, the lens stops down as you move the aperture ring. Thus, as far as Av is concerned, it thinks you're metering at the wide open stop all the time. (Usually, we have to dial in some exposure compensation to get the readings right.)

However, as I explain above, the Adaptall-2 screw mount adapters do not support the M/manual aperture setting. Therefore you'd have to modify the mount to hold the pin in - not a difficult thing to do, there are illustrated instructions on a thread here somewhere.
07-15-2010, 07:08 AM   #8
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QuoteOriginally posted by Blue Quote
Also consider getting the m42 mount since it will allow easier operation in Av mode than the P/K adapter would. That's assuming you have a m42 adapter like many of us do. However, the PK/A is great since it allows the A functions. Get you a P/K or m42 mount and be patient and you can get the PK/A cheaper. I saw one go recently for $89 BIN with a lens attached!
just remember on the M42 adaptors there are at least 2, one that gives auto aperture only, with no auto manual switch, and which requires a mod to keep the aperture pin activated, and one meant for the SP2 and Spotmatic F with wide open metering, this second version seems to be a little clumsy with an external gear to convert the aperture movement to the lever movement needed for the pentax cameras.

07-15-2010, 08:24 AM   #9
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QuoteOriginally posted by Lowell Goudge Quote
just remember on the M42 adaptors there are at least 2, one that gives auto aperture only, with no auto manual switch, and which requires a mod to keep the aperture pin activated, and one meant for the SP2 and Spotmatic F with wide open metering, this second version seems to be a little clumsy with an external gear to convert the aperture movement to the lever movement needed for the pentax cameras.
As I have 3 different m42 mounts I'm aware of this. What I didn't mention was that the basic m42 mount can have the pin cemented down (or otherwise) and it solves the problem of lacking the A-M switch. Then its easier to operate in the Av with the green button. BTW, while the Spotmatic II debuted with S-M-C lenses, it was the Electro Spotmatic, ES, ESII and Spot F bodies that support open aperture metering as long as they have an S-M-C, SMC or the geared version of the adaptall mount.
07-15-2010, 08:27 AM   #10
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QuoteOriginally posted by excanonfd Quote
I am trying to figure out how AV mode would be easier with the m42 mount and m42 to K adapter versus Adaptall PK/M mount and I am unable to do so (I don't have m42 mount). Please explain.

Thanks,
With the basic mount (the one without ES/ES II, Spot F support), the pin can be glued down to alleviate the lack of an A-M switch. It will then work by using the aperture ring to manually stop the lens down. This will allow more straight forward use of the Av mode on our dSLR bodies than with K and M lenses. This is a good option if you find this type of m42 mount for $10-15. There is no comparison for a PK/A mount on many of the Tammy lenses though. For use on the Mirror lenses, the P/K mount is more than enough. However, on a lens like the 24mm, I'd rather have a m42 mount with the pin modified/glued than a P/k.

Last edited by Blue; 07-15-2010 at 08:33 AM.
07-15-2010, 05:42 PM   #11
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QuoteOriginally posted by Blue Quote
With the basic mount (the one without ES/ES II, Spot F support), the pin can be glued down to alleviate the lack of an A-M switch. It will then work by using the aperture ring to manually stop the lens down. This will allow more straight forward use of the Av mode on our dSLR bodies than with K and M lenses. This is a good option if you find this type of m42 mount for $10-15. There is no comparison for a PK/A mount on many of the Tammy lenses though. For use on the Mirror lenses, the P/K mount is more than enough. However, on a lens like the 24mm, I'd rather have a m42 mount with the pin modified/glued than a P/k.
I read this three times through and could not make sense of it at all. Then I thought what can't I do in AV mode with PK/M mount? I grabbed the nearest SP lens, replaced the PK/A mount with PK/M mount, and mounted the lens on the K10D. Set the mode to AV and voila la, can't adjust the aperture (stays wide open at all times). It's interesting though in manual mode both shutter speed and aperture are adjustable but metering needs to be set via the green button time and time again as the shoot changes.

It occurred to me then mounting a P645 lens to the DSLR via the P645 to PK adapter would create same situation as what you have described via m42 mount. I proceed to try that as well and bon! It is really ironic that a completely manual lens coupled to the modern DSLR could be used with a certain degree of automation and the more modern lens need to be shot at manual mode to get the same degree of control.

This has been an interesting lesson, thank you. I think I will pick up at least one aftermarket PK mount from eBay.
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