It took me a while to track down a Topcor-S in a good shape. Finally I managed to score a mint 2nd iteration (which seems to be the most common) with super clean optics.
It arrived yesterday so I wanted to take it out for a spin immediately but it was pissing down all day so I had to wait.
This morning was still rather cloudy so no sun peaking through the trees for better bokeh effect but I was impatient so rather thn waiting for a better weather / light I went out and run a quick comparison between Topcor and Biotar.
I used Sony a7 with K&F adapters. Shot everything full open at f2.
For the sake of comparison I stacked both vintage lenses against a modern SONNAR 55mm f1.8 (shot at f2)
Very quick run down on the differences between the 2 lenses:
- SIZE
Topcor is much smaller, which is good for me usage wise but I'm not savvy enough to know how that would affect optics
- APERTURE RING
Topcor : 2-16 Regular, clicky
Biotar : 2-22 Unclicked with a pre-set ring
- FOCUS THROW
Topcor : Very short. Shorter than collapsible Summicron, which I believe is somewhere in the ballpark of 180°. Topcor is probably somewhere aroun 90°, maybe a tad bit more.
Biotar : Super long, I think it was nearly 360°. Strangely enought I felt Topcor was a lot easier to precision focus.
- CLOSE FOCUS DISTANCE
Topcor : 100cm
Biotar : 45cm
This one clearly goes to Biotar. 1m is not nearly close enough. It might turn out to be a serious problem for close up portraiture.
- SHARPNESS
This is highly subjective but I felt Topcor was a lot sharper full open.
I am surprised how close the Topcor is to Biotar. I still feel the Biotar produces tiny bit nicer images but Topcor is definitely in the ballpark. Very happy with it... I suppose it's safe to say that Topcor-S is the LTM Biotar, next time anybody asks.
Pictures run in order of:
1. SONNAR
2. BIOTAR
3. TOPCOR












