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10-16-2012, 01:25 PM   #1
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Anyone knows how to clean the oil on the aperture blade?

Hi everyone,
My so loved Pentax 50mm f1.7 is dying.
Damn this morning when I examine into it I found the aperture blades are oiled =(
Why this happen to me!!!
Anyway I'm thinking reparing it. However most tutorial I found so far is to M50,.no F 50.
i have a set of 6 screwers. Anything else needed? or do is there any threads there I can follow?

Please let me know
Thanks!
Heartbroken Bing

10-16-2012, 01:55 PM   #2
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I've cleaned some lenses, but they're all manual focus lenses.

I would not attempt to perform surgery on a priced autofocus lens, especially if I hadn't done that before.

You may want to send it to Eric.
10-16-2012, 02:01 PM   #3
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Eric?
10-16-2012, 02:01 PM   #4
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Check this out, its not a F50 but a FA50 and it can be a starting point.
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/197889-fa50-di...djustment.html

Also this, basics are same
http://members.shaw.ca/hargravep/70-210.htm
and
http://ricehigh.blogspot.com/2011/01/disassemble-old-takumar-f-28-80-zoom.html

10-16-2012, 02:37 PM   #5
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lets start with have the blades slowed donw, or otherwise causing inconsistent exposure?

if no, leave it alone,

If yes, the cost of that lens does not warrant sending it anywhere so give it a go, I got an M50/1.7 for $30 a few months back, and passed recently on an A50/1.7 for $50 so 50/1.7's are cheap.
10-16-2012, 03:24 PM   #6
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QuoteOriginally posted by Lowell Goudge Quote
the cost of that lens does not warrant sending it anywhere so give it a go, I got an M50/1.7 for $30 a few months back, and passed recently on an A50/1.7 for $50 so 50/1.7's are cheap.
F50, as hinted by the OP, is not cheap, at least by my standards:

QuoteOriginally posted by hongzhibin1987 Quote
...most tutorial I found so far is to M50,.no F 50.(
10-16-2012, 03:35 PM   #7
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QuoteOriginally posted by jmarkku Quote
Eric?
This Eric -> Linky.
10-16-2012, 04:04 PM   #8
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QuoteOriginally posted by SOldBear Quote
F50, as hinted by the OP, is not cheap, at least by my standards:
My bad, i mis read the post

10-16-2012, 04:16 PM   #9
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+1 for Eric, he has CLAed oil from my K85/1.8 ($35.00) and K20/4 ($40.00) and they are perfect now.

Phil.
10-16-2012, 08:46 PM   #10
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If you focus to the minimum distance you should see three screws on the barrel just above the manual focus ring. Unscrew those (mine were very tight, be careful and use a JIS screwdriver) and your lens will look like this:



From there, you have to remove the front group of lens elements to access the aperture blades. I can't remember exactly what the F50/1.7 looks like here. I would try to unscrew the beveled piece around the front element. It may come off and expose three screws like in the photos of an FA lens disassembly above. Anyway, don't unscrew anything because that will remove an assembly that includes all the lens elements and aperture in the center, with no access to the blades. You need lens spanners to get the front group out, or an improvised tool, used in the square slots in the photo. Or maybe you can get a good grip on it and the group isn't too tight. Then you can access the front of the blades. The rear lens group has visible spanner slots (the outer ones) just inside the light shield. You might have more room if you remove the light shield too, really tiny screws in the mount side below the bayonet lugs.

After that, get some cotton swabs and a solvent for oil, such as lighter fluid (naptha) or mineral spirits. The blades can be cleaned in place if you repeat the cleanings several times, that's what I usually do. I'm not sure how to remove individual blades on the F series. That gets a little fussy but it is more thorough.

Warning: at first, it looks like you should stick a flat blade screwdriver into slots in the focus ring and pry it off. Don't fall for this. I am convinced this is a trick by Pentax lens designers.

Last edited by Just1MoreDave; 10-16-2012 at 08:52 PM.
10-16-2012, 08:57 PM   #11
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Original Poster
Hi Guys,
I was so flattered that so many pantaxian replied this thread...this made me the day =)
And, I will just send an email to Eric, and see how many he will charge on this case.
I really like the F50, that's why I dont event think of selling it.
To ultraviolet: Thanks for the links. Even I probably won't disassemble it by myself it is so cool to see how pros doing these;
To Soldbear: Thanks very much for Eric's!

To others: Thanks, and many thanks for answering my question.
Best,
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