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Learning to repair lenses...

William Guy

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I'm looking to learn how to fully clean/repair lenses more than simply puffing with a blower and wiping with a cloth...

I have a bunch of old P

entax SMC lenses that I don't mind pulling apart (two of them have a little fungus) and want to use them to practice repairing old manual primes. Unfortunately I can't find much online, nor any books on the topic. I have even tried to find information on specific lenses (Pentax, Nikkor etc.) but still nothing detailed.

So essentially I am asking if anyone knows of books/websites etc. here I might be able to learn anything related to pulling lenses apart, cleaning/repairing them, and putting them back together again (all stages being vital!).

I understand that this is as much a science as a skill, with precision and math being vital... but surely the talented folks repairing lenses haven't all learnt through apprenticeship?

I've been pulling apart and re-assembling things since I was a kid (to various degrees of success), and sooner or later I'm just going to dive in... so please educate me before I make a mess!



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welcome to the forum William

I hope someone can help you out this this .......


I have followed a few youtube dismantling tutorials on some of my lenses, its fiddly work and you need to remember what went where....

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Cheers Andy!

Julian... That video is helpful, I'll try and dig up some videos more relevant to the Pentax glass that I'll begin with!

Any other lens repair info is very welcome; fixing loose focus rings, stiff aperture rings etc.


I know that there is a lot of science behind working on lenses, such as calibration. There are plenty of videos showing how to 'de-click' these old lenses (thankfully)... but little on the specifics of how to fully service them, such as checking and adjusting their mechanics.


All the best. Your replies are appreciated!

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I've opened a Nikon 50mm E Series prime lens and an old manual focus Sigma 80-250mm zoom lens (Pentax K). Neither of these were expensive, so it wasn't much of a risk. The 50mm E Series was easy to open up, and easy to get back together again.


The Sigma zoom however... I tried getting it back together for 30-40 minutes or so, but no matter how I tried assembling it, something with the zoom mechanism went wrong - I couldn't get it to zoom the whole range, just perhaps a third or a half of the original zoom range. It wasn't a lens that really mattered to me, so I didn't bother spending more time on it. But, from my own experience and from what I've heard from the camera service shops in town - zoom lenses in general are much more complicated if you need to open them up fully, and will take a lot more time to service.


Personally, I wouldn't open up any of my AF lenses. Even though I'm not fully certain that it is so - I'm expecting them to be more complicated and that there's a risk of misaligning something.


My own conclusion:

If it's older primes that aren't much worthy because of their current condition, I'd open them up and attempt service myself. Zoom lenses - I guess it depends on their design and what part of them that you need to service. The one I attempted service on had to be fully disassembled to clean the lens I needed to clean (oil spots). Had I not had to disassemble it entirely, it would have been a lot easier to assemble it since I wouldn't have needed to disassemble that zoom mechanism.


For cleaning elements, I'd ask some camera lens service shops. I asked at one of the local shops about cleaning coated elements here in Stockholm, and they were very happy about giving advice. According to them one of the best fluids for cleaning lenses (this was in the context of older lenses, I'm unsure if they advised it for only those or for newer lenses as well) was acetone. Before using something like acetone on a lens though, I'd strongly recommend to google around and find out more about the risks of using such a fluid for cleaning lenses. Here's one discussion about that at least: http://www.pentaxuser.co.uk/forum/topic/will-using-acetone-to-clean-a-lens-affect-smc-coatings--35361


Another good tip: Try to see if you can find some *very* cheap lenses in a second hand shop or such and use those for learning.

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This site is excellent for info on manual lenses and has good info on care and repair, getting a basic toolkit together and all that.






That forum is a goldmine! Should have everything that I need, or at least hold the right people to ask.



Many thanks!

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Yes very helpful friendly members there, frequented the site for many years.


Here's a SMC Tak breakdown, scroll down below the Canon FD bit:




And a short list ;-) of links to repair breakdowns and such:




Have you also tried pentaxforums?




Biggest contention I've found over the years has been what sort of lubrication to use for smooth focus and I settled on this, which has worked well:



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