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03-18-2011, 08:13 AM   #1
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How to take apart an M 50/1.4?

Hi All -

I have an M 50/1.4 with a little something between rear elements (probably fungus). I am considering taking it apart to clean, as an interesting project more than the best route to restoring it. (That would be sending it to be cleaned). Does anyone know of a good step-by step guide to disassembly?

Thanks! Nick

03-18-2011, 11:26 AM   #2
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QuoteOriginally posted by Nick Siebers Quote
Hi All -

I have an M 50/1.4 with a little something between rear elements (probably fungus). I am considering taking it apart to clean, as an interesting project more than the best route to restoring it. (That would be sending it to be cleaned). Does anyone know of a good step-by step guide to disassembly?

Thanks! Nick
There's a few videos on Youtube showing how it's done. One, is pretty quick, and the other is a little more detailed. However, there are a few step by step instructions as well.

This link will show you how to take one apart: Pentax 50mm repair 1

It's a Pentax -M 1:2 50mm but it will give you an idea what might be needed if you have to take it all apart.

Here are a few more links you might want to read 1st as well.

https://www.pentaxforums.com/forums/pentax-beginners-corner-q/72755-repairing...m-1-1-7-a.html

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/136247-cleanin...ml#post1421086

Here is a great link for maintenance and repair.
Maintenance and Repair Articles - PentaxForums.com

Have fun..
03-18-2011, 11:36 AM   #3
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QuoteOriginally posted by Nick Siebers Quote
I have an M 50/1.4 with a little something between rear elements (probably fungus).
If that's all you need to clean, you can likely get to everything necessary by simply unscrewing the rear element with a spanner wrench.

H2
03-18-2011, 11:50 AM   #4
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QuoteOriginally posted by pacerr Quote
If that's all you need to clean, you can likely get to everything necessary by simply unscrewing the rear element with a spanner wrench.

H2
I love the KISS method..

Do you know if everyone decided on what was the best cleaning agent to use to remove and kill fungus?

03-18-2011, 04:53 PM   #5
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Alas, I can get 2 elements out through the back but the fungus/stuff appears to be on the inside of the next one. May be time to send it to Eric, I suspect too much more manipulation on my part will leave it unrepairable. Hmmm.
03-18-2011, 05:16 PM   #6
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I haven't looked at the links yet but just in case you are having trouble getting off the front ring, a good way I figured out is to use the core of a toilet roll with Blu-tack attached to the rim. Press it on the ring and turn. Worked very well for me. A bent set of pincers can replace a spanner for the next step. I once cleaned a 50/2 and it was easy to get to all elements.

Last edited by Class A; 03-18-2011 at 08:34 PM.
03-18-2011, 07:52 PM   #7
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QuoteOriginally posted by Class A Quote
in case you are having trouble getting off the front ring, a good way I figured out is to use the core of a toilet roll with blue tag attached to the rim. Press it on the ring and turn.
I'm not following the blue tag. What blue tag? You wouldn't have a picture by any chance. I'm looking for whatever can make it easier for myself as well to remove parts without damage to them.
Thanks
03-18-2011, 08:36 PM   #8
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I meant something sticky. I got the product name wrong, it is "Blu-Tack". A used chewing gum would probably do as well (yuck ). The professional tool is a rubber ring of the size of the front ring. You cannot hurt the lens during this step as the tool necessarily needs to be a bit soft. Getting the ring below off it is more dangerous if you don't have a dedicated spanner tool. But with care you can do it without scratching the lens. I did it multiple times without problems.


Last edited by Class A; 03-18-2011 at 08:41 PM.
03-18-2011, 09:11 PM   #9
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QuoteOriginally posted by glee46 Quote
...I'm looking for whatever can make it easier ... to remove parts without damage to them...
Go to a nearby hardware or auto parts store with your lens(es) or at least their ring diameters. Tell 'em you want the fat-ist, sticky-ist, squishy-ist O-rings they have for those diameters. If they're not sticky enough, daub 'em with rubber cement. Then try to find that famous crutch tip or drain plug (or any cylindrical object) to press on the O-ring.

Find a set of leaf-type feeler gauges at a used tool place. With a little nippin', grindin' and filin' you can make any size leaf-type spanner wrench.

QuoteQuote:
The professional tool is a rubber ring of the size of the front ring.
Nope. The professional answer is the cheapest trick that'll get 'er done. It's the amateurs that get suckered into the catalog tools.

H2

[You DO understand that the LBA-equivalent here is to acquire a used 7x12" Harbor Freight machine lathe with 4-jaw chuck and allocate it to the camera budget fund, right? But it's gotta be used and less than the cost of a bargain K100D.]
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