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Old Aug 21, 2010, 10:35 AM   #1
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Default Tamron Adaptall Mount

I am considering getting the Tamron 28-105 F2.8 that requires an adaptall mount. Is this a generic mount for Pentax or do I need a specific mount for the lens? Does the mount degrade the lens like a teleconvertor? Thanks in advance.

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Old Aug 21, 2010, 3:40 PM   #2
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I am considering getting the Tamron 28-105 F2.8 that requires an adaptall mount. Is this a generic mount for Pentax or do I need a specific mount for the lens? Does the mount degrade the lens like a teleconvertor? Thanks in advance.
Hi pboerger,

I'm familiar with the Adaptall 2 system, but I don't see this lens listed in their offerings. I also cannot find this lens listed under the Adaptall heading. I'd inquire further to get a more specific description of the lens before buying it. The only Tamron 28-105/2.8 lens I've heard of is an AF lens, and AF lenses are only available in dedicated mounts for each mfg.

I've found that the best source for info on Adaptall lenses is at:

http://www.adaptall-2.org/

FYI, the Adaptall 2 (A2) system consists of 2 classes of MF lenses (the standard A2 and the SP A2 which were the "professional grade"). The lenses were made with a generic A2 mount on the lens and adapters for the various SLR mfg mounts available at the time would allow the lens to be fitted to just about any SLR camera made. These adapters did not have any optics, and did not degrade images to any degree. They just compensated for differing register distances and mounts of the different camera mfgs.

For Pentax K mounts, there were two different adapters made, the PK and the PK/A. The first had no electrical contacts, and only allowed for fully manual exposure. The latter had the contacts, and would mimic the function of "A" series lenses, allowing for auto/program exposure and camera body control of the aperture. All of the A2 adapters were officially discontinued a few years ago.

Because of the high degree of backwards compatibility of Pentax DSLR bodies to "A" series lenses, the PK/A adapters were quickly snatched up, and their value on the market rose accordingly. I was lucky enough to have realized the potential of these lenses and was able to find a number of adapters at local camera shops before the rush. I paid an average of @ $20 USD for my PK/A adapters, but it's not unusual to see them on the used market for $100 and up now. PK adapters are more common, and can usually be bought for @ $30 USD.

I currently have and use 4 different A2 lenses: an SP 300 f2.8 LD (IF), an SP 180 f2.5 LD (IF), an SP 80-200 f2.8 LD, and an SP 500 f8 Cat. IMO, all of these are easily at least in the same class optically as the best currently available lenses in their respective FLs and speed classes.

Scott
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Old Aug 21, 2010, 8:00 PM   #3
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Thanks very much for the reply. This isn't simple, is it? Below you will see what I am considering from B&H. Is this a correct combination? What am I getting here?
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Old Aug 22, 2010, 12:17 AM   #4
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hi pboerger,

I stand corrected! This is a surprise to me -- it's a currently offered lens, is listed on the Tamron site, and it's an Adaptall 2. My impression was that the whole Adaptall 2 line had been discontinued by Tamron. I'm assuming that it's the same optical formula as the AF model. The AF model has received mixed reviews AFAIK, with most of them being either very good or very poor, with little in between. This seems to indicate possible QC issues, so I'd think it would be a good idea to get your hands on an adapter before ordering the lens. You'd want to be able to test the lens right when you get it so you can take advantage of the return policy if the lens doesn't perform well. If the lens doesn't work out, if you buy the adapter for the right price, you shouldn't have much trouble getting your money back out of it. Of course you could always keep it in case another A2 lens catches your fancy.

The A2 80-200/2.8 is a truly great lens if something longer might work for you, and it can be found for a lot less than the AF alternatives. . .

Scott

I just noticed that it's a refurb -- I'd say that this might increase the possibility that it's a good one optically.
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Old Aug 22, 2010, 1:42 AM   #5
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I'll second what Scott says about the 80-200/2.8 It's the lens I have on my E-1 most of the time now. I was able to get an Adaptall to 4/3rds mount with AF confirm from KEH but they don't have one for Pentax. I can't really comment on the quality of the 28-105 but if don't need the length for a fraction of the cost you can get the SP 35-80 which is one of the sharpest zooms they ever produced. If it were me I'd go with that and the aforementioned 80-200. Oh, wait, I did

John
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Old Aug 22, 2010, 3:10 AM   #6
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I'm sorry folks, but I'm not understanding. Does this combination work?
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Old Aug 22, 2010, 6:29 AM   #7
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I'm sorry folks, but I'm not understanding. Does this combination work?
Hi pboerger,

This lens would work with your KX as an Manual Focus "A" series lens with the PK/A adapter (able to use Auto Exposure/Program modes, with full control of the aperture using the e-dial on the camera body instead of the aperture ring), and as an MF/manual exposure lens with the PK adapter. Although there's no "A" position per se on the aperture ring of the PK/A adapter, the smallest aperture setting on the adapter acts as the "AE" position, allowing metering wide open and automatically closing down the aperture for the exposure.

The problem is that this listing is for the lens only, and they apparently do not have any adapters for Pentax in stock, so you'd have to find one elsewhere before you could mount the lens on the camera and use it at all. This is why I suggested that you get an adapter before ordering, or you'd not be able to test or use the lens until you did, and the return period would likely run out before you could put the lens through its paces.

I know it's weird. Here's a link to a page where the first pic is a shot of the lens and the adapter separated:

http://www.mattdentonphoto.com/cameras/adaptall-2.html

An appropriate adapter must be mounted on the lens body before the lens can be mounted on a camera body. It's actually an ingenious system, and Tamron had to jump through a lot of hoops to make it work so well with so many different mounts. Here's a link to a Tamron brochure that illustrates most of the different mounts that the Adaptall 2 system works with:

http://www.adaptall-2.org/brochures/...979/page17.jpg

Hope that makes things a bit clearer. . .

Scott

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Old Aug 22, 2010, 10:53 AM   #8
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It is clear. What is clear is that I would not touch something this complicated with a 10 foot Bigma. The link to Matt's site was more than interesting. Quote: "NOTE: for Tamron lenses with a max aperture of f4.5 or slower, use aperture priority AE or manual modes when a viewfinder-indicated aperture value is faster than the original max aperture to avoid accidental underexposure. Don't ask me, that's what the manual says."

No thanks. And thanks for the information that kept me from being a very unhappy shooter. Unfortunately, there is no other f2 lens in that range. I have the primes, but was looking for a zoom. 50mm is to far to start and too close to end.
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Old Aug 22, 2010, 11:55 AM   #9
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It is clear. What is clear is that I would not touch something this complicated with a 10 foot Bigma. The link to Matt's site was more than interesting. Quote: "NOTE: for Tamron lenses with a max aperture of f4.5 or slower, use aperture priority AE or manual modes when a viewfinder-indicated aperture value is faster than the original max aperture to avoid accidental underexposure. Don't ask me, that's what the manual says."

No thanks. And thanks for the information that kept me from being a very unhappy shooter. Unfortunately, there is no other f2 lens in that range. I have the primes, but was looking for a zoom. 50mm is to far to start and too close to end.
It's really not complicated at all. You buy a lens, a mount for the body you need and put the two together. Then when you want another lens you buy it and switch mounts back and forth. I have 3 Adaptall2 SP lenses as well as the 1.4TC and an extension tube made from an ugly grade 2x TC. Granted I don't have the "A" option so everything as manual for me so it's simple, just mount the lens, set the aperture and let the camera choose the shutter speed. Like I said, the 80-200/2.8 is my primary lens now.

John
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Old Aug 24, 2010, 6:53 AM   #10
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You might also want to look at a (somewhat) similar Pentax lens in this range - the A 35-105 F3.5
Just a bit slower F-stop than you were seeking, but a really fine sharp lens with great color rendition too. Often available used at $100 or less...
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