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01-19-2009, 06:59 AM   #1
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Small problem with Auto Chinon 50mm f/1.4

I've got me a Chinon 50 mm 1.4 for a few bucks and I had some little time to play with it. Although I'm quite content with the results (see below), there is a little problem with this lens as I noticed as soon as I had it in my hands: there is a little backlash (is this the right word???) in the aperture ring, influencing the aperture a little. So, given a certain aperture, the ring can be twisted a little, moving the blades also. BTW: this does not happen when full open!

Anybody any idea whether this could be fixed? Has any of you experience in doing it yourself? Help most welcome!

So, as promised, some first results, in which I played a little with DOF and bokeh... All with lens wide open, ISO 400, handheld. Uploaded they look to be a soft, but this is very much less so at original format....

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Last edited by Rense; 01-19-2009 at 07:04 AM. Reason: Wrong picture included... fixed
01-19-2009, 07:05 AM   #2
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does this matter?

the light meter should take care of this unless it is excessive (i.e. more than 1/3 of a stop.)
01-19-2009, 07:16 AM   #3
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QuoteOriginally posted by Lowell Goudge Quote
does this matter?

the light meter should take care of this unless it is excessive (i.e. more than 1/3 of a stop.)
Hmm, I don't know. It is certainly not excessive, but noticable. What you say means that after measuring exposure (in my case pressing the K20's green button) I should not touch the aperture ring, not even slightly. Or not? Knowing myself that seems quite unrealistic..... But probably you're right, probably it doesn't matter and is it only the odd feeling of a somewhat wobbly aperture ring that disturbs me....
01-19-2009, 07:38 AM   #4
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Hi Rense,
you could check the screws on the backplate. See if they are not loose, also if somebody before has 'used' them.
Then, you could try to unscrew the back, carefully lift off the backplate and hopefully have access to the aperture ring and the problem with it.
On the lenses I have had, loose things always came from loose screws or threads.
All success (your photos look like the glass is really good!),
Georg (the other)

01-19-2009, 07:40 AM   #5
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any lens-porn photos?
01-19-2009, 08:37 AM   #6
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QuoteOriginally posted by elkarrde Quote
any lens-porn photos?
A quicky, not the very best, but for you addict....







01-19-2009, 08:40 AM   #7
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QuoteOriginally posted by georgweb Quote
Hi Rense,
you could check the screws on the backplate. See if they are not loose, also if somebody before has 'used' them.
Then, you could try to unscrew the back, carefully lift off the backplate and hopefully have access to the aperture ring and the problem with it.
On the lenses I have had, loose things always came from loose screws or threads.
All success (your photos look like the glass is really good!),
Georg (the other)
Hi Georg, thanks for your tips. I already looked at the screws, but couldn't see loose ones. Don't have a fitting screw driver however, so a real check isn't possible without the risk of dammaging things. But I will try to tighten them certainly, or open the lens otherwise. Thanks again! R
01-19-2009, 12:11 PM   #8
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QuoteOriginally posted by Rense Quote
A quicky, not the very best, but for you addict....
thanks, that's one nice-looking lens!
and fast glass is a fast glass, regardless of it's manufacturer..

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