Unfungusing a Minolta MD 50mm 1.7

Jesito · Expire: 2015-01-07

After watching the thread from Ian (http://forum.mflenses.com/viewtopic.php?p=1214663#1214663) where he shows the sharpness of this lens, I was impelled to try mine.

Unfortunately the lens was stocked some 10 years and developed fungus.
This is the way I've been able of cleaning them.

There were marks on both sides of the lens.
The top element showed something that I'm not sure were fungus. It might well be some nesting from some small insect:

On the bottom side it was a little different, infestation in a couple of spots (difficult to see in the picture) with spiderweb like shape:

To access the top block, the first step is to unscrew the label plate with a rubber tool:

Then remove the three screws that hold the filter thread holder:

Then remove the filter thread holder, and remove the three screws that keep the lens block in place:

Once the block freed, cleaning is done with hands cream for half an hour, washing and drying and setting it in place again:

The bottom lens block is easy to remove: just unscrew these three screws and you are done:

Just remove the baffle on top and pick the block with a suction cup:

The cleaning process is the same: hand cream for 20-30', careful washing and drying and setup in the reverse sense.

Then you have a clean, useable lens:

Hope this will be useful for someone else.

Regards.
Jes.

Orio · Expire: 2012-12-04

Why the hand cream, Jes?

Attila · Expire: 2025-11-18

Many thanks Jes!

bob955i · Joined: 15 Apr 2007 Posts: 2495

Jesito · Expire: 2015-01-07

Jesito · Expire: 2015-01-07

indianadinos · Expire: 2011-12-05

inombrable · Joined: 20 Mar 2012 Posts: 545 Location: Salamanca, Mexico

Totally agree,

I've cleaned quite a lot of lenses with fungi and amonia and isopropanol didn´t have any effect on them but cold cream after 10 minutes did the job and left the lens looking great.

Even once it helped to clean a rear element with haze from a vivitar zoom i fixed, not completely but it reduced the haze A LOT.

Nelson · Posted: Sat Apr 21, 2012 7:28 am Post subject:

sorry

what is "hand cream"

something to wash the hands as a soap ?
or is it a cream to protect the hands when weather is cold ?
thank you

Jesito · Expire: 2015-01-07

iangreenhalgh1 · Expire: 2014-01-07

Thanks for this info Jes, I have a couple of lenses that have fungus that ISO Alcohol wouldn't remove, I shall try the cream!

Jesito · Expire: 2015-01-07

xe0ps · Joined: 20 Apr 2013 Posts: 2

Is there a way to open lens block itself? I have fungus on bottom of 1st lens Sad

Attila · Expire: 2025-11-18

xe0ps · Joined: 20 Apr 2013 Posts: 2

Attila · Expire: 2025-11-18

I think this is glued block you can't clean it at home for sure, to pay for clean not worth it, enjoy little fungus not impact picture quality.

Lloydy · Expire: 2022-01-01

I agree, clean what you can and don't worry too much about a tiny bit inside a sealed block. I've cleaned leses, with the excellent 'cold cream', and left the hard to get at elements alone. It's always improved the lens to get the large infestation out, but a little shouldn't be a disaster to the image.

Aanything · Expire: 2014-05-30

+1
I have a super takumar 3.5/35 that came with fungus - a lot of it.
I cleaned it all, except the face of one element that is part of a sealed group: the lens works like charm, and I can't imagine it being more sharp or contrasty than it is now.
So, my advice is: store the lens right (in a dry, exposed to uv and dust free ambient) to make fungal growth as slow and difficult as possible, and clean what you manage without risking any damage to the lens.
There are good chances that you'll end up with a perfectly usable lens, with no noticeable differences from a clean one.

sammo · Joined: 04 Jan 2012 Posts: 223 Location: CH and SI

I never tryed to use cold cream for cleaning fungus. It was almost always cleanable with 50% aqueous IPA. If it wasn't then 100% IPA or water and soap did the trick. ....or I was lucky until know and never encountered "hard to clean" fungus?

VTGCS · Joined: 23 Apr 2014 Posts: 2 Location: Bogota, Colombia

Hi, I'm sorry for posting on this thread which has been dead for a year and a day exactly... i've been a regular of this forum for about 2 years but this is my first post. I just wanted to thank you because I could fix my minolta 50mm 1.7 with these pictures.

THANKS!

clie · Joined: 18 Sep 2014 Posts: 5

I've managed to clean the lens block.
A lot of trouble but it worked. This lens is so cheap, its better to buy another one. However if anyone is game, here's how to disassemble the sealed lens block.

There are 3 elements.
You cannot access the elements from the front. Go via the back.

I melted the glue from the base of the block using paint stripper. Just soak the bottom element. The bottom element just dropped out after 2 days.
The 2nd element is held together by a ridge on the plastic rim. This was the most difficult as there is no retaining ring - its just snaps into place. It's too tight to suck it out with a suction device. To get this out, I made a small hole to the side of the block in between the 1st and 2nd element, push a tooth pick inside and pushed the lens out. Be careful not to scratch the elements doing this.

Putting them back was was easy - the 2nd element just snaps into place with a little finger pressure. The 3rd element had to be re-glued. I used silicon, then repainted it black (the paint stripper had removed all the black paint).

No more fungus Smile

philslizzy · Joined: 07 Aug 2012 Posts: 4745 Location: Cheshire, England

I'm sure I read somewhere on this forum that an acid in hand cream/cold cream is what moves fungus. perhaps uric acid or boric acid that is harmless to minerals but works on organic materials.