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01-07-2013, 02:54 PM   #1
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Which Adaptall II adapter for K10D

I am new to Pentax and recently purchased a used K10D body, I have a number of MF Tamron SP lenses that I would like to use on this body in the Auto Aperture Mode, Searching the auctions and KEH I see some Tamron Adaptall II adapters with electrical contacts, that are quite expensive, while the others without are not. I am assuming those with the contacts are for Tamron SP auto focus lenses. Am I correct that the cheaper standard focus Adaptall II will allow the Tamron MF lens to operate in the AE mode on the K10D?

01-07-2013, 03:04 PM   #2
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I don't think there is such a thing as "Tamron Adaptall adapter for autofocus lenses." All of them are for manual focus lenses. I'm sure someone will correct me if I'm wrong.

To use Av mode, you need a lens, or an adapter, with electrical contacts.

There are ways to use lenses without electrical contacts in Av mode (e.g. not attaching it all the way to meter in stop down mode), but I found them cumbersome.
01-07-2013, 03:10 PM   #3
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Adaptall

There are two kind of Adaptalls for Pentax

1. Just the regular adaptall 2 that make the lens behave like a K or M lens.
There is a K.M and the P/K mount one.
Prices for this goes from $10 - $50. Average price is $20-$30 all depending on condition of the adapter.

2. There is an adaptall 2 with the Electrical contacts. It makes any Tamron Adaptall 2 lens behave as the Pentax-A lenses.
It says in the mount as PK/A.
Prices for this goes from $50 - $135. Average price is $75-$80 all depending on condition of the adapter.

There is not such things as AF adaptall.

I always recommend the PK/A version since the aperture can be used.

I have the K.M., the P/K and the PK/A


I hope it helps.
01-07-2013, 03:26 PM   #4
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The KA Adaptall mount with contacts will give "in body" aperture control to all Adaptall lenses SP or otherwise. Av mode then becomes available as SOldBear points out. I agree they are sought after and a bit expensive but you only need one adapter that can then be used with multiple lenses. The normal K adapter without contacts works just fine with "green button" exposure methods. I have both types and they work fine with my K10D, and there are some great Tamron lenses available for good prices (seconhand of course).
Cheers

01-07-2013, 03:42 PM   #5
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Thanks everyone for the great help.
01-07-2013, 04:00 PM   #6
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Has anyone used the generic kind (e.g. Fotodiox) that has no mechanics at all? I'm assuming that still allows the lens to be stopped down (which means it would have to hold the level down on the lens 100% of the time), so it would operate like an m42 in manual mode? I think I would prefer that in some cases.
01-07-2013, 05:18 PM   #7
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QuoteOriginally posted by vonBaloney Quote
Has anyone used the generic kind (e.g. Fotodiox) that has no mechanics at all? I'm assuming that still allows the lens to be stopped down (which means it would have to hold the level down on the lens 100% of the time), so it would operate like an m42 in manual mode? I think I would prefer that in some cases.
Third party adapters are by far the cheapest (avg 15.00 on eBay) and operates like an m42 lens (stopped down metering). If you are shooting with any of the mirror lenses, this is all you need or if you are like me and forget to press the green button to meter with KM mounts. The viewfinder getting dark as the lens is stopped down may bother some people but with a good split prism focus screen, I can get fairly accurate focus down to f8 and smaller depending on the lighting conditions.
01-07-2013, 05:50 PM   #8
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QuoteOriginally posted by excanonfd Quote
Third party adapters are by far the cheapest (avg 15.00 on eBay) and operates like an m42 lens (stopped down metering). If you are shooting with any of the mirror lenses, this is all you need or if you are like me and forget to press the green button to meter with KM mounts. The viewfinder getting dark as the lens is stopped down may bother some people but with a good split prism focus screen, I can get fairly accurate focus down to f8 and smaller depending on the lighting conditions.
I use m42s all the time so I am used to that. I have the huge 70-350mm 05A and it has a focus-shift when stopping down due to spherical aberration. So you get better results when focusing at your intended stop rather than wide-open. Right now I have to hold down the optical preview when focusing.

01-07-2013, 06:15 PM   #9
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Keep in mind that most Adaptall lenses, like the old K and M Pentax lenses, have apertures that close in a linear function to the diameter of the iris. True A lenses (and all afterwords) have apertures that close in linear function to the area of the iris.

The end result is that, even with A contacts in the adapter, you will get erratic exposure measurements, sometimes more than 1 stop, depending how far you stop down the lens. A good test to see if the lens+adapter has that condition will be to take a series of exposures in AV mode by setting the F-stop in camera and let it calculate the exposure. With linear area, all images will me more or less correctly exposed. With linear diameter, the wide open and fully closed will be correct and all other will be off.

Best way to use an adaptall lens is using the aperture ring and the green button, or use one of the cheap adapter without an aperture level in AV mode, that essentially behave like an M42 manual lens.
01-12-2013, 11:05 PM   #10
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I also use some Tamron Adaptall II lenses with my K10D and they work great with the PK/A adapter. I have a 300mm prime, a 60-300, a 70-210 (?), and very nice 90mm SP Macro which takes beautiful pictures, as do all of the them.
01-13-2013, 12:44 AM   #11
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QuoteOriginally posted by demp10 Quote
Best way to use an adaptall lens is using the aperture ring and the green button, or use one of the cheap adapter without an aperture level in AV mode, that essentially behave like an M42 manual lens.
It's well-known that "aperture ring and green button" metering with M lenses is not accurate, especially for K10D and K20D. K7 and K5 are slightly better, but still far from accurate.

The smaller the aperture, the more pronounced the overexposure error.

Stoped-down lens and Av mode is not much better either.
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