How do i service a lens

[Falkenberg]

just got this old Zeiss Anastigmat nad the aperture is very hard to work. I was thinking about oiling it. Do I just take off the front lens element and place a drop of oil on the blades or is there an other a better way ?

[Dan Fromm]

The problem you have probably isn't due to, um, diaphragm blades needing lubricant. It most likely due to crud in the barrel, between the diaphragm control ring and the barrel. I don't know how to get your lens' diaphragm control ring off, I do know that if you oil the diaphragm you'll regret having done so.

[Falkenberg]

Hmm, that was what I feared. I dont want to ruin it. I have tried to google any references for the lens, but there is no detailed instruction on how to take the lens apart. It is useable as it is. The glass is very nice and clean.

[Emulsion]

There is a superb camera and lens repair forum at:
http://www.kyphoto.com/cgi-bin/forum/discus.cgi

The forum is called "Maintenance and Repair".

If you haven't already done so I would suggest asking on that forum as well.

Emulsion.

[orto]

First try to get to the aperture. If (!) you manage to do so, then clean it, rather than oil it. If you don't get to the aperture, send it for cleaning. You oil a shutter mechanism, never the aperture or shutter blades. They work best clean of everything.

[Whiteymorange]

On the old lenses I've fiddled with, the problem has always been in the outside ring of the iris adjustment, not with the blades. I sometimes use a tiny drop of oil outside a brass lens, where the knurled ring for changing aperture is, but never on the blades. It attracts dust, eventually sticks the blades together and generally screws things up. I have used a small amount of graphite, rubbed from a soft pencil point onto the leaves of the iris and then carefully smudged with my finger. No problems yet, at least on the ones I didn't completely ruin in getting to the iris in the first part! (First rule of Whitey's world: Never screw around with anything that isn't already broken.)

[Dan Dozer]

I've worked on two lenses that had similar problems - a Cooke with a very hard to turn appature ring and a Dallmeyer that the appature was stuck in one position. In both conditions the problem was that the anchor mechanism that was holding the appature blades in the barrel. One was screwed in too tight and one was in crooked causing the diaphragm to bind.

In both instances, I had to get to the inner workings of the lens where the appature was, so either the front or rear lens needed to be unscrewed. There usually is either a tiny (and I mean tiny) screw on the outside of the barrel or a threaded ring that is removed with a spanner wrench. Removing either of these two things will likely not hurt anything, but make sure that you stop short of taking out the appature blades. If the blades come out, you can clean them and put them back in, but it could be a process that takes several very frustrating hours getting them all back in. If you do try to take out the blades, my experience is that the larger the lens is, the easier it is to get the blades back in. Small lens are much more difficult to reassemble.

If all this sounds too intimidating, take it to professional to get it worked on.

[Falkenberg]

I have so far removed some oily stuff from the blades and have oiled the outer ring and now it all moves. a little harder at both ends, but it works. I am thinking about having it cleaned professionally. A shop here in Copenhagen have offered to do it quite cheap.