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05-14-2021, 11:00 AM   #1
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6x7 105/2.4 no infinity focus

Just received a lens from eBay, seller did not disclose yellowing of the lens, and so I decided to address this myself, though just found out today that the lens has no infinity focus - very blurry at infinity

With that said, does anyone know what might cause this, and or whether its even worth trying to fix?

05-14-2021, 11:17 AM   #2
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Have you ever taken a lens apart?
If so You can probably "fix" it.
The yellowing is not really a problem, but it too can be addressed- without disassembly.

Any other problems?

How is the close focus? Got a picture of something you've made to post?

Of course the simple thing is to just return it for a refund.
05-14-2021, 11:31 AM   #3
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Hi and thanks so much for responding.

I have taken two 42 lenses apart in the past, one to clear aperture blades, and the other to remove a stop bearing, for cine-conversion.

Beyond that, I haven't had any experience with lens disassembly.

As for returning the lens, that is not a possibility, as I opened a case for the yellowing, which was then closed as I took too long to return the lens - and so now, I am no longer able to return the lens.
05-14-2021, 11:32 AM   #4
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I don't know about your lens, but I have a vintage lens where the lens element in the back was inserted the wrong way after a cleaning.
Close focus was okeyish, but infinity was unuseable.
If you don't want to return the lens, this might be worth trying.

05-14-2021, 12:48 PM   #5
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QuoteOriginally posted by JohnBee Quote
Hi and thanks so much for responding.

I have taken two 42 lenses apart in the past, one to clear aperture blades, and the other to remove a stop bearing, for cine-conversion.

Beyond that, I haven't had any experience with lens disassembly.

As for returning the lens, that is not a possibility, as I opened a case for the yellowing, which was then closed as I took too long to return the lens - and so now, I am no longer able to return the lens.
Sounds like you have enough experience and knowledge to disassemble the 67 lens.
I would suspect it has been apart before and someone re-assembled it incorrectly. The focusing helicoid may be a thread or two off; or as mentioned above, the elements may be inserted wrong.

You have nothing to lose !

A lesson for all of us here; to be sure and test all functions of a new purchase while it can be returned/adjusted.
05-14-2021, 05:33 PM   #6
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QuoteOriginally posted by DonV Quote
Sounds like you have enough experience and knowledge to disassemble the 67 lens.
I would suspect it has been apart before and someone re-assembled it incorrectly. The focusing helicoid may be a thread or two off; or as mentioned above, the elements may be inserted wrong.

You have nothing to lose !

A lesson for all of us here; to be sure and test all functions of a new purchase while it can be returned/adjusted.
Hi and thanks again for all your help with this.
With that being said, do you have any tips on how I could adjust the helicoil to get the focus right?

ie, would mounting it on a digital camera allow e to check the focus capabilities of the lens?

---------- Post added 05-14-21 at 10:12 PM ----------

Also, I forgot to ask this, but is there a way to tell if any of the elements are improperly installed in the lens?

Last edited by JohnBee; 05-14-2021 at 05:42 PM.
05-14-2021, 06:59 PM   #7
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You will have to try the helix position by trial and error, but you won't have to put it all the way back together to check it.
It always helps to be the first one to take it apart, but mark the alignments anyway- that way you won't duplicate the "wrong" ones.

Reversed or misassembled elements should be pretty obvious; I think it is more likely the helix position.

You didn't say if it would focus at any distance, if it will - what distance and what does the scale indicate? Is the picture sharp at some setting?

05-14-2021, 07:14 PM   #8
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QuoteOriginally posted by DonV Quote
You didn't say if it would focus at any distance, if it will - what distance and what does the scale indicate? Is the picture sharp at some setting?
I will check and report back

---------- Post added 05-14-21 at 11:56 PM ----------

QuoteOriginally posted by JohnBee Quote
I will check and report back
Okay, I have tested and infinity in in focus, at about 5ft

---------- Post added 05-15-21 at 12:00 AM ----------

Also, the lens will focus up-to about 13-14" at it's nearest setting
05-14-2021, 07:38 PM   #9
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Since the minimum focus is supposed to be about 39", I'd say there is a strong likely-hood that the helix is one or two threads off.
05-14-2021, 07:53 PM   #10
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QuoteOriginally posted by DonV Quote
Since the minimum focus is supposed to be about 39", I'd say there is a strong likely-hood that the helix is one or two threads off.
That is an encouraging analysis
With that said, would I need any special tools to get to, or adjust the helix?

Last edited by JohnBee; 05-14-2021 at 08:20 PM. Reason: spelling errors
05-15-2021, 06:56 AM - 1 Like   #11
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Correct size screw driver(s), spanner, perhaps rubber ring to remove a trim ring; nothing extraordinary.
10-01-2021, 11:58 PM - 3 Likes   #12
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Just wanted to update this thread in case someone else encountered the same issue.

After buying a spanner and successfully removing the rear element of the lens, I learned that it was backward - after reversing and trying it out again, everything proved to be normal - lens focused as it should.

Following this, came the arduous task of reassembling the lens without dust and blemishes - which turns out to be an arduous task, as cleaning and assembling a lens without dust and smudges is most difficult to do without specialty cleaning wipes - as conventional methods do not work well - at least not in my own experience.

In addition to this, this lens also had what I'd consider, severe yellowing, and to the point of affecting image quality, and so I decided to try a UV treatment.
I also learned that this was only applicable to the rear element stack, and so I took advantage of the lens being apart to place each individual element on a UV lamp, as this would spare the lens from excessive heat and potentially damaging something in the process - plus it was much easier to construct a shroud and holder out of carboard and aluminum foil for the individual lens elements than with the entire lens itself.

With that said, I did the deed using the following UV lamp; "Everbeam 395nm 10W UV LED Black Light" - which I purchased on Amazon for 19.99 CAD
All in all, the deyellowing process took aprox 3 days per element, resulting in crystal clear elements afterward - night and day difference and very satisfying to do imo.

Well that's about all there is to report on this - all in all, an eBay seller tried to rip me off, and somehow managed to get away with my money on both eBay and Paypal - luckily, my CC company was able to get me the money back, though I had to invest in a drive spanner, lens ring removal tool and UV light, which totaled aprox. 160 CAD with shipping and fees, as well as the money lost to customs due to not returning the item for a refund - no physical return = no duty and customs refund...

Having said all that, and on a brighter note, I did however, end-up with a moderately good 105/2.4 67 lens, and so I guess it's not all bad news

- hope this helps someone somewhere and thanks for the help

Last edited by JohnBee; 10-04-2021 at 10:48 AM.
10-02-2021, 09:29 AM   #13
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Thanks for the update
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