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GN Topcor M 50mm f/1.4 test
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PostPosted: Thu Feb 14, 2019 12:36 am    Post subject: GN Topcor M 50mm f/1.4 test Reply with quote

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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PostPosted: Thu Feb 14, 2019 3:28 pm    Post subject: Reply with quote

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


PostPosted: Thu Feb 14, 2019 3:39 pm    Post subject: Reply with quote

caspert79 wrote:
I can't say I'm in love to be honest. Bokeh is very busy!

That's the first thing that came3 into my mind also, even though ,after watching it few3 more seconds, there the nice glue behind the subject isolation. I wouldn't call it very sharp lens wide open, but i do believe the conditions weren't the most apropriatte to show the best of this lens,and i3 still believe this lens has good potential for portraits


PostPosted: Thu Feb 14, 2019 5:28 pm    Post subject: Reply with quote

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.


PostPosted: Thu Feb 14, 2019 5:40 pm    Post subject: Reply with quote

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/


PostPosted: Thu Feb 14, 2019 6:04 pm    Post subject: Reply with quote

caspert79 wrote:
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/


There was a noticeable improvement in my opinion. It is the same lens as in the link and I think the photos correspond well to my results. I think it's a matter of differences in light, subjects and compositions that we see here.

My samples were not taken with great care and they have been heavily adjusted.

F/2 sample

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PostPosted: Thu Feb 14, 2019 6:14 pm    Post subject: Reply with quote

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

Btw does your copy focus smoothly?


PostPosted: Thu Feb 14, 2019 6:19 pm    Post subject: Reply with quote

Massive improvement @f/2!


PostPosted: Thu Feb 14, 2019 6:47 pm    Post subject: Reply with quote

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 Smile

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


PostPosted: Fri Feb 15, 2019 10:52 pm    Post subject: Reply with quote

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.


PostPosted: Sat Feb 16, 2019 6:58 pm    Post subject: Reply with quote

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!