GN Topcor M 50mm f/1.4 test

[blotafton]

First off it's a big lens with 62mm filter thread. Focus throw is very short. Similar to the Minolta Rokkor 58mm f/1.2 stopping down to f/2 makes a big difference.
Taken with a Sony a7.

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[caspert79]

I can't say I'm in love to be honest. Bokeh is very busy!

[kiddo]

[blotafton]

I do agree on the smoothness assessment. Closer focus will make it smoother.
Notice how the shape of the bokeh changes shape towards the edges. It follows a trend I have observed, which is that lenses with this characteristic often have more busy bokeh. Also seen in my Planar vs Prakticar comparison thread.

So far with my limited usage I'd say that it's somewhat similar to my Prakticar 1.4/50 ver. 1. Including softness/glow towards infinity at f/1.4.

[caspert79]

I'm curious whether the bokeh will improve at f/2. So far I have seen mixed results with Topcor lenses. Is the lens from this link the same as yours? Bokeh is pretty smooth here.
http://www.flickriver.com/photos/astroman-photo/sets/72157626245790731/

[blotafton]

[y]

Thanks. It's always nice to see a relatively rare 50 in action.

Btw does your copy focus smoothly?

[caspert79]

Massive improvement @f/2!

[blotafton]

The focus has too much resistance but is consistent. The rubber has lost it's grip on the inside and wants to slide free. This makes it somewhat hard to focus. But nothing a MF veteran can't handle

It's much worse on my 58mm 1.8 Topcor, there the rubber just fell off.

[John Shriver]

Unless you've cleared it with UV light, the glass is stained tea-brown by the radioactive element with thorium in it. Mine make the geiger counter sing. (As does my radioactive screw-mount Summicron.)

It is necessary to remove all the grease and re-lubricate the cam focusing system, the original grease reacts with the brass cam and turns to "green glue". The path in is pretty obvious, and I think I've posted instructions before.

[blotafton]

Mine must have already been UV cleared because there is only a slight brown color and I could use my normal white balance.

New lubrication would be nice!