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Pentax SMC FA* 85mm 1.4 - Disassembly(partial) and fungus cleaning
Posted By: shyrsio, 01-30-2020, 08:18 AM

Hello everyone!
I happened to lay my hands on a copy of the FA *85/1.4 which was in a bit of a misery. Although physically mechanically it felt solid, the optics were riddled with fungus. The lens is the early version without the trims under the aperture ring and the old style hood. After consulting the internet for a while I noticed there weren't any guide to disassemble/repair the lens. From outside I could spot at least 4 layers of fungus through the elements. Anyway I decided to dive in and see if I could save the glass.
So here is a little guide to a partial disassembly of the lens, and I hope somebody else can complete the pieces to a total disassembly.
Disclaimer: this disassembly reaches the fifth element of glass from the front and is about the mechanical parts related.

Step 1: Using a spanner rotate the retaining ring atop the front element until it comes loose

Step 2: Unscrew the front elements block. To do this you need the spanner again. Attention: this element is calibrated which means you have to mark its position relative to the barrel. My copy had some sort of paste on the barrel and an little bulge on the lens group which left its mark on the paste, anyway, i marked both with a graphite pencil. when unscrewed pay attention when lifting the gals from the body, its quite heavy, I used a rubber glass sucker. I wiped the back surface and the fungus marks came off quite easily, there seems to be no visible damage from it.

Now the first element of the focusing group is exposed, this element is screwed tightly to the aperture mechanism.

Step 3: removing the element in front of the lens. This is a little tricky and requires some steady hands, since these are anti-reflective surfaces and they scratch easily..
* * * *
* * * Before I go on there is an optional step that I did which may not be required for step 3
* * *Optional Step 2B: Removing the focus ring and barrel* * * first make a vertical line through the front barrel, focus ring and body in both nearest and furthest focus points. Then remove the 6 retaining screws on
* * * the inside of the barrel. Now you can lift the focus ring/barrel combo. Side-note: I kept the focus ring in the manual focus position the whole time.
* * * now the barrel is shorter and the electronics are showing, also you have more working space for Step 3.

... the 4th element is glued to a metallic plate screwed atop the aperture mechanism. this unscrews using a spanner but i found out its too tight at first. There's an outer plate is held in place by 5 tiny screws. I unscrewed the 5 screws and noticed the aperture lost its spring mechanism. so screwed them back on while still loose, I tried the spanner again on the 4th element and this time was pretty loose, so I'd say, loosen the outer screws a bit before unscrewing this element.
I was happy to find out that this element also was recoverable from fungus. I cleaned it and I set is aside.

Step 4: For cleaning the front of the 5th element I simply opened the aperture totally and cleaned it with a cloth and detergent.*
Upon checking the lens through a light i noticed that all the fungus layers were gone. Thank god I didn't have to dig anymore. Apparently the last 4 elements are sealed tight together and there hasn't been contamination from fungus.
I put everything back in place in the reversed order and "voila".

Side note: there are now some tiny specs of dust inside the lens, but it's nothing in comparison to that ugly fungus.
If anybody has some word of advice about how to keep the dust outside, and also on what chemicals to use to prevent future fungus infestations, that would be very welcome.
PS: I really hope this thread helps somebody of you folks, I always feel grateful about the guides and advice's I find on this forum!

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01-30-2020, 10:27 AM   #2
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This is excellent, thank you.
01-30-2020, 11:32 AM   #3
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Wow, I hope I never need to go this far with my copy, however thanks for a great job with your description and photos on the procedure. You have a great lens there and no doubt will enjoy the pictures you take with it.
01-30-2020, 02:37 PM   #4
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QuoteOriginally posted by garywakeling Quote
Wow, I hope I never need to go this far with my copy, however thanks for a great job with your description and photos on the procedure. You have a great lens there and no doubt will enjoy the pictures you take with it.
I have to admit, it was a thrilling adventure, not knowing weather I would save it or brake it. but the outcome is amazing. this lens really deserves the praise it gets!

01-30-2020, 07:20 PM   #5
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QuoteOriginally posted by shyrsio Quote
I have to admit, it was a thrilling adventure, not knowing weather I would save it or brake it. but the outcome is amazing. this lens really deserves the praise it gets!
Yes it is a ripper, I went off it during the APSC years and once the K1 arrived it made it's way straight back to the camera bag
01-31-2020, 07:41 AM   #6
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That was brave and it paid off. Congratulations and thanks for sharing the information.;
02-02-2020, 11:48 AM   #7
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Hi, realy intertresting. I've 2 big dusts in the front lens of my FA 85mm.
Did you use a spanner tools ?

02-03-2020, 03:13 AM   #8
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QuoteOriginally posted by Le Fanfoué Quote
Hi, realy intertresting. I've 2 big dusts in the front lens of my FA 85mm.
Did you use a spanner tools ?
yes indeed, use the spanner for the first two steps.
03-06-2020, 01:28 AM   #9
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QuoteOriginally posted by shyrsio Quote
yes indeed, use the spanner for the first two steps.
Hi, I did it ! Bur you need a very good spanner, because all the rings are torked hardly.
and the second ring had glue to brake it.
problem to solve, the diaphragm brings dust to each operation ... I must reopen the lens, and suck all this dust ...
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03-06-2020, 03:18 AM   #10
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QuoteOriginally posted by Le Fanfoué Quote
Hi, I did it ! Bur you need a very good spanner, because all the rings are torked hardly.
and the second ring had glue to brake it.
problem to solve, the diaphragm brings dust to each operation ... I must reopen the lens, and suck all this dust ...
Glad you did it! Attention, the "glued" second ring has to be realigned to where it was i think.
03-11-2020, 07:53 AM - 2 Likes   #11
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QuoteOriginally posted by shyrsio Quote
Glad you did it! Attention, the "glued" second ring has to be realigned to where it was i think.
Hi :
http://www.pentax.le-fanfoué.net/010%20Pentax%20FA85mmf1.4.html
Sorry, I can't translate all this tutorial...
if it can help someone.


Fanfoué
05-22-2020, 01:50 AM   #12
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QuoteOriginally posted by Le Fanfoué Quote
Hi :
http://www.pentax.le-fanfoué.net/010%20Pentax%20FA85mmf1.4.html
Sorry, I can't translate all this tutorial...
if it can help someone.


Fanfoué
Thank you Fanfoué,
I wish I had seen it earlier!
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