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01-14-2014, 11:46 PM   #1
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Does 'CLAing' a lens destroy it?

Would like to hear others opinions. My take is - it probably will.

Recent example - 2 F1.4 50mm 8-element M42 Takumars. One clearly was 'CLA'ed' (holes drilled in serial ring). Other was not - came off its original Spotmatic.

There is a striking difference in sharpness between the two (seen in text when used with a Q with Fotodiox adapter. Multiple shots - hand held - but multiple shots were taken to offset shake and focus errors. Best of each shown.). First - CLAed - 2nd No CLA.

We all know that elements are not completely symmetrical. At manufacture, special collimating equipment is used to orient for best results. Does this happen with the typical CLA? Maybe there are exceptions - but my guess is - no.

What are your opinions? Will you by a 'CLAed' lens? Or never?

Your experiences??

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01-14-2014, 11:57 PM   #2
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Sounds like a crappy CLA. Why would anyone drill holes in lenses?!
01-15-2014, 12:03 AM   #3
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QuoteOriginally posted by Giklab Quote
Sounds like a crappy CLA. Why would anyone drill holes in lenses?!
It is a last resort for a very stubborn name ring.

Is the CLA'ed one ever sharp? It is possible that they might have reversed an element when they reassembled it.
01-15-2014, 12:23 AM   #4
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Nothing wrong with CLAing a lens, it is no big deal. You just have a lens someone did something stupid to, and yeah they probably put it back together wrong. I've never had one become unsharp by taking it apart and putting it together again...

01-15-2014, 12:26 AM   #5
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Just because they say it was CLA`d does not mean the work was done competently. Without knowing who did the work, a knowledgeable repair person or a ham handed amateur, I don`t think you can say one way or the other.

If someone offered me a lens CLA`d by Eric I would not hesitate a second.
01-15-2014, 01:19 AM   #6
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Even brand new, modern lenses exhibit sample variations.

You cannot make any conclusion from this, especially when you do not know how the CLA'ed lens performed BEFORE the operation.
01-15-2014, 01:29 AM   #7
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QuoteOriginally posted by elliott Quote
It is a last resort for a very stubborn name ring.

Is the CLA'ed one ever sharp? It is possible that they might have reversed an element when they reassembled it.
I recently had some correspondence on Takumar Club thread about a much better method to get a stubborn vanity ring off.
https://www.pentaxforums.com/forums/122-lens-clubs/31601-takumar-club-821.html post #12306.
01-15-2014, 02:17 PM   #8
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Too many unknowns here to jump to a conclusion. Don't even know WHY it might have been opened to begin with.

A properly done CLA should be beneficial in any case -- presuming it was necessary at all.

01-15-2014, 02:48 PM   #9
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QuoteOriginally posted by cahudson42 Quote
One clearly was 'CLA'ed' (holes drilled in serial ring).
Sounds like a botched repair attempt. Any repair tech worth his salt can remove the face ring without drilling. In fact, most good repair techs can do their work with little indication when they are done that they were there at all.

I would do a close inspection of the inner elements of the suspect lens using a loupe and oblique light. I betcha one or more of the inner elements are scored.


Steve
01-15-2014, 03:11 PM   #10
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It is Clean - Lubricate - Adjust.

There is no 'D' in CLA.

Just sayin'
01-15-2014, 03:53 PM   #11
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QuoteOriginally posted by jatrax Quote
If someone offered me a lens CLA`d by Eric I would not hesitate a second.
+1, he does real good work. I had some fungus and some light oiling on the aperture blades.
Came back as good as new.
01-15-2014, 10:09 PM   #12
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QuoteOriginally posted by cahudson42 Quote
One clearly was 'CLA'ed' (holes drilled in serial ring).
No one who knew what a CLA is would drill holes in a lens. That's like drilling holes in a car hood to get at the engine, instead of opening it with the latch.

Phil
01-15-2014, 11:10 PM   #13
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QuoteOriginally posted by gofour3 Quote
No one who knew what a CLA is would drill holes in a lens. That's like drilling holes in a car hood to get at the engine, instead of opening it with the latch.
This is assuming that the lens has not been tampered with previously. I have come across some lenses that were "repaired" where the person used super glue instead of proper thread locker on the retaining rings. Usually, some solvent and/or careful use of heat will loosen the rings but sometimes it's not practical (e.g. plastic bezel) to do so or it just plain refuses to budge.

Also, if the lens has been dropped or knocked, such that the filter attachment area is misshapen, even slightly, then friction force is not enough to generate the torque required to remove that front bezel.

Last edited by tom1803; 01-15-2014 at 11:34 PM.
01-16-2014, 05:42 AM   #14
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QuoteOriginally posted by tom1803 Quote
This is assuming that the lens has not been tampered with previously. I have come across some lenses that were "repaired" where the person used super glue instead of proper thread locker on the retaining rings. Usually, some solvent and/or careful use of heat will loosen the rings but sometimes it's not practical (e.g. plastic bezel) to do so or it just plain refuses to budge.

Also, if the lens has been dropped or knocked, such that the filter attachment area is misshapen, even slightly, then friction force is not enough to generate the torque required to remove that front bezel.
In those cases wasn't the lens already functionally 'destroyed' by the first 'CLA' or before the 'CLA'?
01-16-2014, 01:24 PM   #15
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QuoteOriginally posted by monochrome Quote
In those cases wasn't the lens already functionally 'destroyed' by the first 'CLA' or before the 'CLA'?
In either case, I would consider it unethical to resell a lens that had been "repaired" in that way.


Steve
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