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Some success finally with the SMC 50/1.4
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PostPosted: Thu May 20, 2010 1:54 pm    Post subject: Some success finally with the SMC 50/1.4 Reply with quote
I have battled with this lens for a while.

It focus' past infinity on my camera, and what is in focus in the viewfinder, is not in the images. It back-focuses by a considerable margin.

This was taken close to wide open, sorry i didn't take notes! Either 1.4, 2 or 2.8.

There was a considerable yellow cast to images that was corrected in lightroom




PostPosted: Thu May 20, 2010 2:02 pm    Post subject: Reply with quote
If the focus differs between your viewfinder and sensor, isn't that an indication of a miscalibrated focusing screen?


PostPosted: Thu May 20, 2010 2:20 pm    Post subject: Reply with quote
beautiful smooth whites roses!


PostPosted: Thu May 20, 2010 2:22 pm    Post subject: Reply with quote
If you have the original (AF) focusing screen, that problem is common. It's not really back-focusing, just the screen unable to cope with a lens more open than f2.8.

Your lens would benefit of a good UV bath to de-yellow the back element. Mine regained an half-stop after the "operation".


PostPosted: Thu May 20, 2010 2:34 pm    Post subject: Reply with quote
Scheimpflug wrote:
If the focus differs between your viewfinder and sensor, isn't that an indication of a miscalibrated focusing screen?


I would have thought that, but other lenses have nowhere near the same issues.

poilu wrote:
beautiful smooth whites roses!


Thanks poilu.

Jieffe wrote:
If you have the original (AF) focusing screen, that problem is common. It's not really back-focusing, just the screen unable to cope with a lens more open than f2.8.

Your lens would benefit of a good UV bath to de-yellow the back element. Mine regained an half-stop after the "operation".


Great information Jieffe, i did not know about this! I will try focusing at 2.8, then open back up Very Happy

I had planned on leaving the lens in direct sunlight, then had second thoughts about the heat causing other issues. Can you tell me more about UV baths?


PostPosted: Thu May 20, 2010 5:47 pm    Post subject: Reply with quote
rpo83 wrote:
[Great information Jieffe, i did not know about this! I will try focusing at 2.8, then open back up Very Happy

I invested in an Ebay split-focus screen and never regretted it. Works fine at full aperture. For my other DSLR, I bought a broken Minolta SRT and cut the screen. Works fine too.

Quote:
I had planned on leaving the lens in direct sunlight, then had second thoughts about the heat causing other issues. Can you tell me more about UV baths?

Some members here used uv lamps to de-yellow their lens. I simply disassembled the rear lens and let it on a window sill for a few weeks.

This way, no risk of overheating the helicoid grease and faster results (as the light doesn't have to travel through several layers of glass before reaching the yellowed element).
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