How I cleaned the fungus from inside my 50mm F1.7 (pics)
Apr 8, 2011
Well without any technical knowledge or particular skill, but a love of tinkering and investigating and an essentially 'free' lens that wouldn't have been any real loss had I failed...I decided to tackle trying to clean away some fairly bad fungus growing inside a lens I bought.
A quick description for those who don't know the story from another thread - I bought 2 SLR bodies and 6 lenses, plus filters, caps, boxes, manuals, cases, etc from someone looking to unload some old film gear - grand total was $100 for the whole thing. Of that, I was particularly after a few key lenses - namely a Konica 40mm F1.8, 50mm F1.7, Vivitar Series One 28mm F2.8, and Vivitar Series One 70-210 F3.5. Upon viewing them, all were in near-new shape, except the Konica Hexanon 50mm F1.7, which had the fungus. I was going to just buy the other 3 lenses, but then he offered to throw in a Chinon and two Chinon lenses (50mm F1.9, 135mm F2.8), both of which were in very nice condition too - and he didn't want to have any part left - so I offered to take it all at $100 - figuring the Hexanon 50mm F1.7 might end up in the trash...the money I spent was worth all the other lenses, so it wasn't a loss.
Which left me in the position of having a 'throwaway' lens - already written off in my head, and really nothing to lose in trying to clean it up. I've never opened up a lens before, so I dug around for some basic instructions online, and despite my own fears and the warnings of others, it didn't look too challenging. And again...nothing to lose. Besides, if it worked, the Konica Hexanon 50mm F1.7 is a bit of a legend as lenses go - routinely labeled one of the sharpest made.
So, here's what I did - this documents the process for this particular lens, but most lenses will have a very similar construction and similar process:
1. What a horrible documentarian I am! I failed to start off with a photo of the actual fungus!! I tried massively brightening this first shot and circled where it is - it was a fairly large patch with some spidery veins running off from it - it shows up here as a large dark shadow area, inside the front element:
2. The front name ring that surrounds the front element is simply screwed on - and to unscrew you need a simple spanner wrench...without one of those, often anything rubber with some traction can work the ring off by friction. I used the rear element lens cap, with an elastic band pressed between it and the ring - counter-clockwise turns and I felt it loosen pretty quickly:
3. Once that's off, you will see 3 screws inside. On the Konica, these held the black metal bezel that makes up the inner lens frame or tube, surrounding the element. I've tilted the lens to try to show the tiny little screws inside:
4. Once removed, the outer tube can be grasped, and turned counter clockwise - it unscrews from the lens - it's deeply threaded and takes lots of turns, but was quite easy and comes right off:
5. Now the lens element assembly is sticking out in the open...it too unscrews counter-clockwise, and is now quite easy to grab. Once you work it off, the lens element comes off as a single piece with the black surrounding plastic...the rear element can now be accessed:
Here's the actual front element assembly, after a cleaning. I carefully wiped the fungus off the lens' element with a damp microfiber towel - not rubbing too hard to avoid abrasions, and turning the towel often to avoid reusing a dirty section. I also went ahead and cleaned out the inside of the lens body. The aperture blades are fully exposed and accessible from the front like this - I closed them town to minimum aperture to avoid anything falling in by the center elements:
That was it - just put everything back in again in reverse - all quite easily. No worries about alignment as everything simply screws back in to its stopping points. I was shocked how easy this process was - I might even consider doing something similar with another older lens I have that has quite a bit of dust inside the front element.
Of course, I went back out and tested the lens just to make sure everything worked properly after my little tinkering! Next post...
