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Fungus Cleaning on a Bronica Zenzanon 75mm f2.8
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PostPosted: Fri Jul 09, 2010 10:37 am    Post subject: Fungus Cleaning on a Bronica Zenzanon 75mm f2.8 Reply with quote

I took apart a Zenzanon 75mm f2.8 lens.

Here is a tutorial written by someone else.

www.buonaluce.com/Slens.pdf

If you look at Pic 5 and 6, the inner and outer optical elements are shown.
However, you will will find that each one has 2 elements.
I am unable to separate these 2 elements no matter what I try.

Has anyone been able to separate these elements on your samples ?
I added a small album with pics of the rear lens element.
picasaweb.google.com/anmol.mishra/RearLens#


So the front and the rear element have 2 sets of the 2 notches where we can use the callipers or a machinist divider or a lens spanner wrench.
I tried to take them apart but ending up scratching the glass - so I stopped for a bit.
I am hoping that they are not glued together - but it does look like that.

Any ideas how to proceed ?


PostPosted: Sat Jul 10, 2010 6:10 pm    Post subject: Reply with quote

In newer lenses many times makers used glue to fix elements.. I met this trouble also and I left in as is. I heard this block can separate with slow heating I don't how you can do it , perhaps in water if you can increase temperature slowly , no idea.


PostPosted: Sun Jul 11, 2010 1:13 am    Post subject: Reply with quote

Hi Attila. I googled this some time ago. Some people tried to put a lens in an oven and slowly increase the temperature.
Some recommended using acetone to dissolve the glue. And some others had a rig with a UV-C lamp that they swore by.
I am sure you are aware of these methods. The fungus is minor and only on the edges. However, I am keen on cleaning them as its my first project.

Would you recommend any of these methods ?


PostPosted: Sun Jul 11, 2010 11:33 am    Post subject: Reply with quote

Definitely NO, high risk for nothing. I have 4-5 yrs experience with fungus infected lenses already if not impact picture quality don't need to clean at all. It is not growing if you not store it in swamp Smile I have several dry boxes for lenses , due humidity is frequently higher than 60% in my home. I bought big transparent plastic boxes and store lenses inside in small open plastic boxes without front cap at least and use old used UV filters as transparent cap on lens front. Also I did put humidity remover into in mass amount this help to keep humidity around 30-40%. I have a dedicated plastic box for fungus infected lens, lenses are in mixed stage some of incredible fungused wait for cleaning some of them has just one small spot.
First lens went to box 4 yrs before with one small spot and even nice company like full mushroom farm , spot didn't grow at all. So finish this project now and enjoy your great lens.If you won't put next to healthy lenses store her separately as I do.


PostPosted: Sun Jul 11, 2010 1:15 pm    Post subject: Reply with quote

Storing them separately is indeed a great idea.I have some containers I can use.

As an idea, I found on ebay an Aquarium UVC lamp assembly for 40 bucks with a 25w bulb. I will cut the front open and place some of my lenses inside.
I will post details later.

I reassembled the lens - and I know I did it right as the infinity aligns with the marker. Also, I can change the iris. Very Happy Also I used up ALL the screws so its all great. However, now there seems to be 2x iris'es, one which is permanently closed and the other that can open and close as needed.
So no light is entering my lens at all. Any idea what I may have done ? There is a small part of a spring that may have fallen from this assembly as well. Shocked


PostPosted: Sun Jul 11, 2010 2:13 pm    Post subject: Reply with quote

Unfortunately I don't have any clue.


PostPosted: Sun Jul 11, 2010 4:50 pm    Post subject: Reply with quote

Thanks anyway. I posted pics anyways.
The 2 aperture levers do not move all theway anymore.
There are 3 pics here
http://picasaweb.google.com/anmol.mishra/Zenzanon#
First pic shows f5.6
Second pic shows the shutter at that aperture. Note that the first shutter is at 5.6 while the second one is closed off.
Third pic shows the shutter at wide open aperture. Note that the first shutter is open while the second one is still closed.