The Tamron 28mm f2.5 lens (model 02B) with the Adaptall-2 mount system is a lens I have owned since 1986. The lens was made in Saitama, Japan by the Tamron Co., LTD.
I purchased it at the time for my Yashica FX-70 35mm camera. I finally decided to give it a try on my Samsung NX1 using a C/Y (Contax/Yashica) to NX adapter (see photo below)
Below are the some specifications I found at AllPhotoLenses.com (click link for additional details on this specific lens:
I went out for a walk around the neighborhood about 1-1/2 hours before sunset. There were thin clouds obscuring the sun at times, but it poked-through for some of these photographs.
All the photographs shown here were "as-taken" JPEG's. There was no post editing with the exception of resizing from the large 23.4 megapixel APS-C sensor resolution. All photographs were handheld and no filters were used, except where noted below the photo with the settings.
Note: I did not record the aperture settings, but I stayed within a range of f5.6 to f11 for this series
1/80 sec / ISO100 / EV 0
1/125 sec / ISO100 / EV 0
1/125sec / ISO100 / EV 0
1/125sec / ISO100 / EV 0
1/125sec / ISO100 / EV 0
1/125sec / ISO100 / EV 0
1/125sec / ISO100 / EV 0
1/125sec / ISO100 / EV 0
1/125sec / ISO100 / EV 0
1/125sec / ISO100 / EV 0
1/125sec / ISO100 / EV 0
f/5.6 / 1/160sec / ISO100 / EV 0 / 0.9 ND Filter
f/11 / 1/160sec / ISO100 / EV 0
F5.6 + half-stop / 1/50sec / 0EV / ISO100 / 0.9 ND Filter
Note: It was interesting to find out that this lens had a minimum aperture setting of f32. I want to go back out in full sun and photograph this essentially "pin-hole" setting. I will post these photographs when available.
Additional information links:
https://www.pentaxforums.com/userreviews/tamron-adaptall-2-28mm-f-2-5-02b.html
https://www.youtube.com/watch?v=Itbnr3ckOwg
http://www.vintagelensesforvideo.com/tamron28mm/
http://lensbeam.com/obektivy/obektiv-tamron-28-mm-f-25-adaptall-2
https://en.wikipedia.org/wiki/Tamron#Adaptall-2_lenses_and_adapters