Soligor C/D 28-80mm f3.5-4.5
This is a nice lens. My copy was most likely made by Sun Optical. It's built very well. Focusing and zooming are smooth. My copy has a little zoom creep. The C/D line was Soligor's best and this lens shows why.
At 28mm it is sharp from f4. Corner sharpness is average.. At 28mm f5.6 it is sharp with better corner performance. At 80mm f4.5 it is usable in the center but the corners are soft. F5.6 tightens it up.
Macro is engaged by a slide button and it engages very smoothly. Macro at 28mm is excellent from f4 up. At 80mm it is soft until f8. It is not true macro but it enables you to do some product photography. It produces a 1:4 macro ratio. I found this lens difficult to focus on the T2i, primarily because it is a one touch zoom. This also becomes an issue in macro mode. It is difficult to hold focus .
Some lenses just aren't practical for use on D-slr's. However, this is a nice lens, and if you manage the focusing issues, it will produce some nice images.
f5.6 - sharp
ISO 400 - f4 - 28mm
ISO 400 - f4 - 100% crop - 80mm
ISO 1600 - f4..5 - 100% crop - 80mm
ISO 400 - f4.5 - 80mm
ISO 1600 - f3.5 & f5.6 - 50% crops
ISO 1600 - f4.5 - 100% crop - 80mm
ISO 400 - corner fringing