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Vivitar 28mm f2.8 .. a cleaning attempt.
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PostPosted: Wed Dec 02, 2015 12:01 pm    Post subject: Vivitar 28mm f2.8 .. a cleaning attempt. Reply with quote

Hi,

I was wondering if someone who knows this lens and is familiar with the structure and disassembling of this lens can provide some info/guidance on how the optics can be disassembled to clean off fungus.

I did make a small album that can be found at the link below. Key may be the lens schematics in the first picture.
http://s72.photobucket.com/user/parodias/library/Vivitar%2028mm?sort=6&page=1

I have no experience with disassembling a lens but I thought it could be fun to give it a try instead of throwing the lens in the garbage. I was able to buy it real cheap, I think.

I have no intention to disassemble the mecahnical part if I can avoid it. There is nothing wrong with it, it is working perfectly all right, only fungus has been noticed, so I want to make an attempt to get rid of that.
I am also well and extensively documented on how to (theoretically) deal with fungus so people can skip that part Wink (I have a long standing professional experience in bio-chemistry & molecular biology which may help a bit Very Happy)

I followed instructions found on youtube (although getting off the name ring was a tough experiment) to disassemble the lens into 2 parts but that does not get me far enough.
In the schematics (first pict in the album) these "2 parts" can be identified the sections 1+2, making one unit, and section 3 the lens unit at the back of the lens.
https://www.youtube.com/watch?v=B0-2B1jiKFQ

In the album, disassembled parts, that top unit, 1+2, can be seen in pict 4. The arrow A points to my presumed opening point but it turned out that the whole body can be unscrewed at point B yielding the two separate lens units 1 and 2 on their own.

The lower and upper lens parts of this unit, 1 and 2 in the schematics can be viewed in picture 5.

Upon further inspection, the fungus, which look like a mild attack(? maybe?), is always situated in between the lens elements of each unit 1, 2 & 3 so I need to disassemble each unit in order to clean the glass. I cleaned the glass parts that are accessible this far and it doesn't change anything to the fungus views inside the lens units, which, IMHO, makes it quite clear where the infections are.

Questions that remain unsolved till now:
- Top unit (schem. #1) can probably be easily put apart because there is a notched retaining ring that can be unscrewed ? (picture 6)
- For the lower part of this unit (schem. #2) I have no clue on how to proceed ! (picture 7) I will provide more pictures of this piece as it may open from below ?
- My nightmare(?) the back unit (schem. #3). (Picture 3 also fungus visible here!) there is a double ring, both with notches. I suppose that the outer one serves to disassemble the whole back lens unit? while the inner one is used to dismount the individual lenses?
So, what to do ? Leave the unit in place and only make an attempt to get out the inividual lenses for cleaning ?
My inexperienced logic would tell me that the latter process would, maybe, cause the least impact on the lens unit alignment or does this bear no relevance?
But I do not know. The only problem I may run into is that, if I remove the whole lens unit, I have no "spanner" system to hold the removed lens unit in order to dismantle the glass.
Thank for reading & looking,
TIA


PostPosted: Wed Dec 02, 2015 5:13 pm    Post subject: Reply with quote

Picture 3. The two notched rings, a lens spanner is pretty much essential - I think the inner ring will only release the single rearmost element. You might be lucky and all the fungus is on that one.
Again, I think that to get to the inner elements the outer notched ring has to be removed - but I'm not sure if the lens group will come out without the flat black baffle plate being removed - there are three tiny JIS screws going in sideways right at the rear of the lens. You'll need the proper JIS screwdrivers for these as they are very small. I would try not to remove the Canon breechlock mount - three larger silver screws inside the mount ring - as there is a world of springs and tiny ball bearings in there that is best left alone. But getting the baffle off will let you see more, I have a Pentax one here without the baffle and I can see how it comes apart, but it's a Close Focus version and the Pentax mechanics are different to Canon. ( I have a Canon and Minolta as well but I don't really want to take them apart )
It's been a long time since I took one of these apart, and it was the Pentax Close Focus version.


PostPosted: Wed Dec 02, 2015 8:39 pm    Post subject: Reply with quote

Thank you very much for your input.
I had another look at the rear of the lens and I see what you mean about removing that black back plate. You are most probably right that it should be removed for easy working. You are also confirming my readings ie to stay away as far as possible of dismounting the FD mount ! .. but that was not my intention in the first place as the mechanical part of the lens seems to work flawlessly.
My attention has already been drawn to the fact that I need JIS screwdrivers in order not to damage the screws so I may order a set of these on Amazon together with a spanner wrench.
I also found a discussion on this forum about the disassembling of the "cousin" lens aka the close focus model. It is funny that a form of "blueprint" for this lens cannot be found by a general search.
PS I went for Canon FD (or Minolta MD) mount lens(es) for the simple reason that I already have adapters to mount these on my Sony A6000. I somewhat, want to avoid starting a collection of mount adapters, although the purchase of an M42-2-NEX may, possibly, be very difficult to avoid !
PS2 yr sig says "lenses for sale" ?? Wink


PostPosted: Tue Dec 22, 2015 2:26 pm    Post subject: Reply with quote

I have an additional Q ..

The parts that screw together and that make the "inside" of the lens, are originally held with some kind of "lacquer" to prevent "auto-unscrewing". This seal is obviously broken when disassembling. It seems to weaken with iso-prop.

Are there any suggestions about what to use to restore the seal? or is this not needed ?

thanks !


PostPosted: Tue Dec 22, 2015 4:09 pm    Post subject: Reply with quote

Rigel wrote:
I have an additional Q ..


Are there any suggestions about what to use to restore the seal? or is this not needed ?

thanks !


Nail varnish or Nail polish (what you call it depends on what country you live in )
Acetone is usually better than isoproponal to soften the old lacquer, this also works on nail varnish but be careful not to get it on any plastic parts of the lens.


PostPosted: Tue Dec 22, 2015 7:15 pm    Post subject: Reply with quote

Thank you for chiming in.

Nail polish has been mentioned to me, indeed, but being a chemistry engineer myself I have my doubts about this material as it may tend to start peeling off as its adherence to metal, and maybe more specific to rough coated metal, may be far from ideal... so I am a bit reluctant to use it. Wink
By principle I avoid "nail polish remover" type fluids which are either based on acetone or ethyl-acetate (worst case: both) ... as such I avoid those solvents in their pure state as well.
Maybe I need to test it by just trying ... Smile