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03-31-2011, 09:23 PM   #1
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M50 f1.4 - Is there hope or just a paperweight???

Hi,

I picked up a M 50mm f1.4 while going through the second hand camera shops in Vietnam to be used with a K5 body. From the reviews on this forum, these lenses are supposed to be quite well respected, and for the price that was on offer, I took the stab to try and clean it up. So now for the question time:
  • From the photos below, is that a decent fungal infection, delamination, or am I looking at another problem all together?
  • Do you think there is potential for it to be fixed, or would I be wasting my time and money?
  • As I will be working in Vietnam for a while longer, and the local shops are not too willing to help out with servicing, would it be possible to take it apart, clean it up, and put it back together without any/too many special tools???
Thank you in advance for all the help.

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03-31-2011, 09:30 PM   #2
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I came across this.....
03-31-2011, 09:38 PM   #3
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Fungus can get bad enough to etch lens coatings. You can't tell whether that's happened until you clean it. So that's one possible bad outcome, not fatal but less good. There's some risk to DIY repair too, if you choose that. It looks like someone has already taken the lens apart or tried, because paint is missing from the spanner slots.

To see if separation is likely, I look at a lens diagram to see where the glued elements are. That's here:



My guess would be fungus, on the surface just behind the aperture blades, because it seems to be highly curved.
03-31-2011, 10:02 PM   #4
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Definitely fungus...

...and it does also looks like someone has attempted a disassembly.

Mike

03-31-2011, 10:10 PM   #5
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I took the lens to a Canon service centre the same afternoon that I bought it, they did open it up slightly, hence the pain missing and the marks, however, they were not too keen to fully disassamble it, as it was not a Canon.
03-31-2011, 10:37 PM   #6
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I am guessing it is possible to have different types of mold and mold probably looks different in different circumstances but I have cleaned out mold from 2 smc tak 50mm and neither of them looked like that. The mold was more like strong hair like tendrils. The 50mm tak come apart pretty easy but you need a spanner wrench to get those slotted retaining rings off.

And like it has been stated mold can etch the coating and I have also heard it can etch glass (although I have never seen this)
04-01-2011, 09:57 AM   #7
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Looks like fungus to me. I have a similar issue and couldn't QUITE get to where I needed to clean it. Haven't decided what to do next.
04-01-2011, 12:14 PM   #8
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That looks to me like it might be fungus on the back side of the glass nearest the aperture disk. If so, it wouldn't be difficult to try to clean it yourself. I'd try pulling the REAR lens group to see what's to be seen through the wide open aperture disk first. Unscrewing the rear element(s) as a group is often easier and quicker than messing with the front group.

A pair of machinist's micrometer calipers with the tip of the blades touched up with a file to fit the ring slots make a good substitute for a true spanner wrench. Sturdy draftsman's dividers - preferably the screw type - also work after a fashion.

Someday I hope to find a lemon 50mm with glass in such condition it can't reasonably be cleaned up and "make lemonade" with it by trying various coatings and masks on selected inner elements to make a true soft focus portrait lens.

Would that be any better than a diffuser filter? I doubt it. But it would be instructive to experiment with the idea and it would provide a retirement job for a once proud lens.

H2

Incidentally, I've got an SMC-A 50/1.7 with a badly hazed rear group that's looking to "mate" with another A-50/1.7 with a damaged barrel or bad front element. PM if you have a candidate.

04-02-2011, 08:39 AM   #9
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QuoteOriginally posted by 1r0nh31d3 Quote
The 50mm tak come apart pretty easy but you need a spanner wrench to get those slotted retaining rings off.
I've used scissors instead of spanner wrench, worked fine
04-03-2011, 06:23 AM   #10
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Its a paperweight.

These lenses can be had quite cheaply.

IMO its not worth the time, effort and money required to fix it if it can be fixed.

Opinions may vary.

Tom G
04-03-2011, 08:24 AM   #11
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Paperweight.
Sacrificial offering.
I hope it was real cheap.

If you want the experience of working on a lens, this is a good candidate. You probably can't muck it up any worse than it is already.

If it was my lens, this is what I would do: Disassemble the glass. Try to clean it. If successful, rejoice! And reassemble. If unsuccessful, discard the glass. Remove the NEW OPTICAL LENS from a one-buck thrift-shop Diana clone. Put that 'lens' onto the M50 body, used as a focusing helicoid. Hey, I might even be able to save the iris!

Anyway, it's probably just a 'parts' lens now. Good luck!
04-03-2011, 08:51 AM   #12
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QuoteOriginally posted by PentAdam Quote
I took the lens to a Canon service centre the same afternoon that I bought it, they did open it up slightly, hence the pain missing and the marks, however, they were not too keen to fully disassamble it, as it was not a Canon.
I live in Vietnam (Saigon, not Hanoi) too and the going rate for a full-service CLA for this type of lens is about 50,000 - 100,000VND (about $2.50 - $5.00). Big stores won't touch those as it's not worth their time, you will have to find those who offer the service at home. Ask around, there should be plenty of places like that in Hanoi as the Hanoians love manual focus lenses.

Good luck!
04-03-2011, 09:53 AM   #13
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Write this lens off. That is a pretty serious fungus problem, and what's plainly visible to me is that the barrel itself is highly suspect. Looks to be covered in gunk and lint and possibly fungal hyphae of its own. The odds of successfully sterilizing that entire lens are pretty low.

However, I second earlier suggestions to play with this lens as a learning experience. Could be a lot of fun to tear it apart!
04-03-2011, 10:32 AM   #14
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QuoteOriginally posted by v5planet Quote
Write this lens off.
I like this repair, but it is for a Super Tak 50mm f1.4. But may not be too different.

http://web.aanet.com.au/bayling/repair.html
04-03-2011, 08:04 PM   #15
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I dropped the lens of at a Local Pentax dealer, there are no guarantees, but will only cost a few dollars for the labour, so I will see how well it scrubs up, and will post a few "After" photos to complete the "Before and After". Judging by the few Super Takumars in pristine condition that were also there, at this stage I am still quite hopeful.

On another note, say that a lens in its dirty mouldy state, has been tried on relatively new body, what are the chances of the mould/fungus spores finding a new home inside the camera body?????
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