Clean fungus prime lens

Sunnyf16 · 09-30-2011, 07:57 AM

I have an old manual focus prime Focal MC 135mm f2.8 & there's a bit of fungus inside at the rear element. It was quite easy to open the outer element. I just have to hand unscrew the black inner most ring. The fungus looks like it is on the inside of the 2nd element (from the mount) However I can't get to the 2nd element.

Just wonder if I need to remove the mount to get further into the lens.

The lens is cheap & not that good to justify professional cleaning which will cost more than the lens, IMHO.

Thanks

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**Just1MoreDave** · 09-30-2011, 11:35 AM

If I don't know anything about a lens, I just keep taking off parts I can get to, until I can access the problem. I haven't seen this lens before, so that's what I'd do. On some Pentax lenses, it's easier to remove the black light shield than remove the mount screws. The light shield is often held in by tiny screws in the side of the mount, under the bayonet tabs. Or just remove the mount.

The most likely designs for this lens have two elements in the rear, so sooner or later you'll find a way that the second element is held in. The usual methods are some sort of threaded ring with slots for a spanner wrench, or a threaded tube with no visible fasteners, that screws into the rest of the lens.

Sunnyf16 · 09-30-2011, 06:49 PM

Thx Dave,

I think I'll start with the tiny screws under the tabs & eventually get to it.
This is the first time I open a lens on a whim, actually. I want to make sure I can put it back together, if I can't fix the problem :-)

I'll take some photos along to way to make sure I can put it back

Sunnyf16 · 10-01-2011, 01:46 AM

Just want to report in what happened.

I took the small screws out under the tab & proceeded to dismantle the lens further. I opened another ring thinking the 2nd element is attached there somehow only to discover it held back tens of tiny ball bearings!

I quickly backed out by screwing the ring back since in the past, I've manage to take apart but not put back quite a bit of stuff or broke them further in the process. So I decided to forget it & clean the elements of dust & found that it rotated! Alas all I had to do was to tilt the lens over & the 2nd element fell out for me to clean.

So I managed to get the lens clean although can't get is sparkling. Need to get some pecpad or new microfiber cloth with purer alcohol or methanol. Will do that again.

**Just1MoreDave** · 10-01-2011, 01:33 PM

Well, points off for me for bad advice. I've never seen the light shield be anything but a light shield.

Sunnyf16 · 10-02-2011, 05:39 AM

Dave,

not your fault. the shield came off with the aperture lever & was fine. Its the next ring I unscrewed that held back the ball bearings. It had some light glue on the threads, sort of to prevent the ring from getting loose. Anyhow, no damage done. And it was "at my own risk".

If anyone wants to try this at home, suggest you try it with a cheap lens or broken lens first :-)

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09-30-2011, 11:35 AM	#2
Just1MoreDave Site Supporter Join Date: Feb 2007 Location: Aurora, CO Photos: Gallery \| Albums Posts: 6,340	If I don't know anything about a lens, I just keep taking off parts I can get to, until I can access the problem. I haven't seen this lens before, so that's what I'd do. On some Pentax lenses, it's easier to remove the black light shield than remove the mount screws. The light shield is often held in by tiny screws in the side of the mount, under the bayonet tabs. Or just remove the mount. The most likely designs for this lens have two elements in the rear, so sooner or later you'll find a way that the second element is held in. The usual methods are some sort of threaded ring with slots for a spanner wrench, or a threaded tube with no visible fasteners, that screws into the rest of the lens.

09-30-2011, 06:49 PM	#3
Sunnyf16 New Member Join Date: Sep 2011 Posts: 6 Original Poster	Thx Dave, I think I'll start with the tiny screws under the tabs & eventually get to it. This is the first time I open a lens on a whim, actually. I want to make sure I can put it back together, if I can't fix the problem :-) I'll take some photos along to way to make sure I can put it back

10-01-2011, 01:46 AM	#4
Sunnyf16 New Member Join Date: Sep 2011 Posts: 6 Original Poster	Just want to report in what happened. I took the small screws out under the tab & proceeded to dismantle the lens further. I opened another ring thinking the 2nd element is attached there somehow only to discover it held back tens of tiny ball bearings! I quickly backed out by screwing the ring back since in the past, I've manage to take apart but not put back quite a bit of stuff or broke them further in the process. So I decided to forget it & clean the elements of dust & found that it rotated! Alas all I had to do was to tilt the lens over & the 2nd element fell out for me to clean. So I managed to get the lens clean although can't get is sparkling. Need to get some pecpad or new microfiber cloth with purer alcohol or methanol. Will do that again.

10-01-2011, 01:33 PM	#5
Just1MoreDave Site Supporter Join Date: Feb 2007 Location: Aurora, CO Photos: Gallery \| Albums Posts: 6,340	Well, points off for me for bad advice. I've never seen the light shield be anything but a light shield.

10-02-2011, 05:39 AM	#6
Sunnyf16 New Member Join Date: Sep 2011 Posts: 6 Original Poster	Dave, not your fault. the shield came off with the aperture lever & was fine. Its the next ring I unscrewed that held back the ball bearings. It had some light glue on the threads, sort of to prevent the ring from getting loose. Anyhow, no damage done. And it was "at my own risk". If anyone wants to try this at home, suggest you try it with a cheap lens or broken lens first :-)