Last night I managed to find some time to take out the Elmar 90mm f/4 screw mount lens (serial number 148xxxx) from my lens pouch and check to see whether it was usable on my FED-2 camera (which it was). However, I managed to wipe the front element with the soft lens cloth but I had a lot of difficulty trying to clean the back element with the cloth because the back element of the lens is so far into the barrel that the best that I could do is stuff the lens cloth down into the barrel and try to wipe. I wasn't all that successful. Questions:

1) What is the best way to clean the rear element of the Elmar lens? I was thinking about using that dust computer aerosol can to blow air and thus wipe off dust from the rear element.

2) Does light haze affect picture quality substantially?

3) How does one distinguish between light haze and fingerprint marks on the rear element?

All the same, I plan to shoot some test rolls using the lens and report back on the quality.

Alfie

-- Alfie Wang (leica_phile@hotmail.com), December 06, 2001

Answers

1) Doesn't this lens unscrew at about one third back from the front, so the front elements can be mounted on a Visoflex? See if it doesn't, then the real element will be accessible. 2) Yes, flare and loss of contrast. 3) Given the difficulty of access, fingerprints are unlikely. Of course they have a distinctive pattern of whirls, and haze tends to be uniform. Shining a flashlight through the lens from behind will highlight issues of fungus, haze, etc.

-- Phil Stiles (Stiles@metrocast.net), December 06, 2001.

I did shine a light through the lens here at work. They aren't fingerprints at all but a very light web of dust(?) on the rear element. I don't know how to distinguish or tell the difference between haze and fungus. However, it doesn't look like fungus to me because there isn't any firm spots which suggest to me that fungus would have etched the glass through.

Alfie

-- Alfie Wang (leica_phile@hotmail.com), December 06, 2001.

On further notice, it looks like there is a "blank clear stripe" in the middle of the lens which lies between the front element and the aperture ring. That particular part of the lens seems to have a very light haze/film across? I think that if I can get a digital picture then I will post the results to explain it through.

-- Alfie Wang (leica_phile@hotmail.com), December 06, 2001.

Unscrew the optical group from the focusing mount. On my Hektor it comes apart just behind the aperture control,

-- John Collier (jbcollier@powersurfr.com), December 06, 2001.

Alfie, I have the same lens. The front 1/3 of the lens screws off of the mount. Grip a part of the front that doesnt move and the same with the back and turn it counter-clockwise. The back will now be easier to clean. Mine has a small amount of haze and surface cleaning marks when observed with a strong light otherwise is see thru clear. It takes good pictures with decent contrast and saturation. A very small amount of either haze or cleaning marks only seen with a strong light source usually doesn't affect performance from my experience.

-- Gerry Widen (gwiden@alliancepartners.org), December 06, 2001.

Thanks guys! I will clean as much of the lens out and will be presenting some photos from it then :)

Alfie

-- Alfie Wang (leica_phile@hotmail.com), December 06, 2001.

Hello Alfie, to clean recessed lens elements the Lens Pen by Ritz cameras is very handy. It has on one side a soft brush and o the other a sort of silk cloth mounted on a rubber element. This silk cloth is also very handy to clean lens elements which are close to sometimes greasy threads (a brush will be more or less unusable if it comes into contact with grease). You get it in every Ritz camera store for about 8.00$. Johannes

-- Johannes Fleischhauer (j.fleischhauer@vsao.ch), December 06, 2001.

You can also wrap 2 or 3 sheets of lens tissue neatly over the end of a Q-tip (use a long-handled one like you see in the doctor's office if need be). Replace the tissue every few wipes. This technique also works well when lens cleaner fluid is needed, as the cotton retains it well. Wipe very gently, of course. Check often to make sure the wood stick isn't about to poke through the cotton.

-- Bob Fleischman (RFXMAIL@prodigy.net), December 06, 2001.