Removing element retainer to clean inside surfaces

[Dr Bellows]

Hi all,
I have a Schneider Symmar 150/5.6 convertible with slight haze in the rear element. I used a loupe to look at the lens surfaces, focusing progressively from the element nearest me to that furthest. The haze is definitely at some point between the external surfaces and appears as an overall swirl, like a cleaning mark.

It is entirely possible that this haze may not cause much loss of contrast, but if not too risky, I would like to clean it. Can anyone suggest a make/model of spanner wrench for the purpose of removing the element retaining ring? Can anyone suggest a procedure for doing this? I would imagine it safer to clamp the spanner in a vise and turn the lens element barrel by hand than visa versa.

Thanks,

[John Schneider]

I would suggest the spanner wrench made by SK Grimes. Built like a tank, extremely adjustable, and the angled jaws give lots of clearance.

If the lens cell retaining ring is loose, I get better control holding the wrench; if the ring is on tight I'll use a tiny bit of penetrating oil (make sure to wipe it up later) and clamp the spanner in the vise. In either event, I cover the exposed glass surface with several layers of low-tack (blue) masking tape.

I use reagent grade xylene to clean the lens surfaces, but then again I have access to it and a fume hood. Because it has an oxygen hanging off, acetone tends to pull water out of the atmosphere, which will cause streaks if you don't wipe it off when still quite wet. Be careful to lay out all the parts (there are often internal rings and spacers) so that you can put it back together.

[ic-racer]

Hmm....if you can see what looks like a swirl or cleaning mark, maybe someone has been there before. This may mean two things.
1) Someone has had the ring off already, so it could be easier to remove again and
2) Someone already tried to 'clean' it and it won't get any 'cleaner.' Which is to say the haze you see may just be residual fungus damage of the coating.

[natek83]

I was able to get the front retaining ring off with a flat head screw driver to clean the inside of the front element of a Schneider Componon-s 150mm. The tricky thing was to work the screwdriver on each side back and forth when the threads gripped one side. I also had to be extremely careful to not let the thing slip and nick the glass. Getting the retaining ring back in was much smother but I had trouble getting the element to seat correctly but once it did the ring went in easily. I had got it recently and it had some fungus or something on the inside. Luckily it has no coatings to be damaged and the fungus wiped off easily.

[Thebes]

I've worked apart several lenses with a two-screwdriver method that sounds similar to what natek83 describes. I have never messed one up but I would hesitate to do it with glass I valued. It helps to have some secure way of holding the lens since there is a mini-screwdriver in each hand... works ok in a pinch, but like I said it is kind of risky, Helps to have one's hands touching as this stabilized the screwdrivers and makes them into a better improvised spanner. I never managed to use a single screwdriver on anything needing a spanner unless it was already loosened.

[Frank Petronio]

The SK Grimes spanner tool is excellent but the large hardware stores near me stock a lighter but just as effective "General" brand tool that costs less and will work for lens mounting and camera repair.

The blue painter's tape is a good idea but a slip will still scratch through.

My camera repair manual shows Tomosy using rubber jar lid twisters, Kleenex, and rubbing alcohol. He may not be Don Goldberg or SK Grimes but I bet he did just fine with the basics.

http://www.amazon.com/Camera-Maintenance-Repair-Book-Comprehensive/dp/0936262869

[Thebes]

Speaking of blue tape, back when I worked making eyeglasses we used a blue plastic tape that stuck to cr39 and polycarbonate, did not leave a residue, and protected the lens fairly well. Does anyone know a source for this stuff and if it is safe for coatings?