Tamron f3.5 28-70mm Adaptall 2

Tamron 28-70 Zoom A2

 

Overview

Nice two touch compact zoom from Tamron in Adaptall 2 mount. For more info on Adaptall-2 see my Adaptall-2 page. The idea is basically that Tamron made mountless lenses that would accept “Adaptall Custom Mount” fittings that were camera-mount-specific. The adapter becomes functionally part of the lens and works basically as an OEM lens would, with a few caveats.

The glass on this lightweight zoom lens is beautiful, though the lens itself doesn’t seem as well constructed as the 2.5 28mm I have, let alone the marvelous 90mm SP. It reminds me of those semi-generic zooms on the lookalike Pentax/Canon/Minolta/Nikon SLRs I used to see at Costco, aimed at the broad consumer market. The front section on mine rocks slightly, simply due to the way the front half is attached to the second with two opposing brass screws. I also don’t know why there seems to be external bayonet tabs on the lip of the lens. To accept a proprietary fitted hood perhaps? I’m told that CF stands for Close Focus, as opposed to the SP series which has Super Performance.

Tamron 28-70 Front

Wish I could say it took pictures worthy of the appearance of the glass, initial tests showed great color rendition if not good sharpness, but that could be attributed to the problem outlned below:

Repairs

It doesn’t want to focus to infinity, which at first made me think I was doing something wrong. But how many ways are there to zoom and focus? I tried adjusting the focal range by loosening the set screws on the lens barrel and by turning it against the distance scale could *almost* get the 28mm end to reach infinity focus. Then the near scale was off by quite a bit. I took apart the top half of the lens and found that it was bottoming out before it could reach infinity focus, so now I think the rear element(s) is/are out of register. It may end up being a parts lens before I’m through with it.

Usage

The zoom-macro feature is very interesting. The focus ring and zoom ring are coupled in a very unique way that is kind of hard to explain. The focal range is limited by the relative focal length. But if you’re at the wide end, 28mm, where your focal range is limited to .7m to infinity, and you try to focus closer, turning the focal ring will actually zoom in on your subject acting as a macro feature until you reach 70mm and arrive at the near focus of .3m. Maybe that wasn’t so hard to explain 😉 It’s literally like having multiple lenses in one package.

As with all Adaptall-2 lenses, open up to maximum aperture prior to mounting or unmounting the adapter.

Truth in Advertising

Sold for parts since I couldn’t figure out the focusing problem, and have other zooms…

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