problem with fd lenses.. help please?

[Andrew Todd]

i have a weird problem... i havent used my fd lenses in a while.. ive been using nikon. but a few months ago i had no problems with them.. now for some reason i cant get them on the fd mount... but its only the fd lenses with the silver ring around the bottom.. like these ones :
http://pondriv.sunnyday.jp/camera/le...ns/fd_5018.jpg

i have the letus35xl version 1 and version 2. and it doesnt seem to work for either anymore.. I know its not the lenses.. cuz i use them on my slr still camera every day.. but i know its not the mount.. cuz i have 2 mounts here and they worked a few months ago no problem... frustrating.. its as if the mount wont sit into the fd lens flush.. and its every lens.

[Andrew Todd]

no one? i feel like an idiot.. i cant understand this.. i used all fd lenses 2 short films ago.. now they wont go on...

[Frank Hool]

sounds like mystery, but are You sure that You don't have any other Canon lens at home... like from front of Digital Photocamera which use EF-S bayonet mount. Those won't mount into FD-mount.

[Andrew Todd]

im just using my old set of fd lenses.. same old-model fds that i used on my first letus35a and 35xl... and my old canon t70 slr.

[Bob Hart]

Andrew.

Check closely the circumferential groove where the lugs for the Canon lenses go.

If you have used the reversable mount for Nikons and had to bring it forward for backfocus, then tightened the thumbscrew firlmly to stop the mount from coming loose, the end of the screw may have bruised the machining on the Canon side of the mount enough to stop your Canon lenses from fitting.

If the mount is a different one from the one you successfully used, then there will be other reasons and my comments might best be ignored.

[Andrew Todd]

im trying it on the mount that i used to work on my 35xl and the brand new mount that just came with my 35xl v.2 and its just the fds with the silver ring. i dont see any indentations that would prohibit the lens from mounting properly

[Andrew Todd]

allright...i figured out the problem.. but not the solution.. half of the fd lenses work .. half dont.

http://andrewtodd.zoto.com/img/45/9f...81953ea45-.jpg

the problem is the little pin.. shown on the left hand side of lens in this pic.. its stuck up on half of the lenses.. stopping the mount from sitting in

[Tony Tibbetts]

I have a 35mm FD lens with the silver ring and I have had no problem mounting it on my Letus. Also, the silver ringed FD lenses mount a little differently. You have to turn the silver ring independently from the lens, whereas the other FD lenses you turn the whole lens itself to mount the lens.

[Bob Hart]

Silly question, but does that little pin draw back if you move the aperture ring after setting manual aperture, or even draw back if you move the mounting ring to the free and locked positions or backwards.

It might be a secondary locking device for the lens to locate into a drillhole in the camera if the camera itself does not have pin lock. If it is, it will may move back when the mount ring is turned, but maybe only if given a starting helping hand.

It might be something like a automotive trunk lid latch which can be inadventently triggered into the closed position and then you can't shut the trunk until you manually unlatch it again with the key or cable release.

Try testing it by applying gentle pressure on the pin while moving both those rings in turn.

I have two third party Canon lenses here. One is a Carl Zeiss Jenazoom. The other is a MTO 1041mm mirror. Inside the Carl Zeiss mount face there are three things sticking out which are not lens controls.

One is a small screw which appears to be a keying device to stop the lens turning. Another is a small latch on a leaf spring. This appears to be a detent for retaining the lens mount collar in the released position as it fits into a relief in the collar when the collar is in the released position.

If the collar has become turned clockwise as viewed from the front, after the lens has been taken off, even if you offer the lens up to the mount with the bayonet lugs correctly matched, the lens will sit high on the little screw. The red telltale on the ring must line up with the white reference mark on the lens barrel in the released position.

There is a THIRD and this may be the most likely cause of your problem. It is a very fine mechanical signal pin which I found only the Carl Zeiss lens. This is situated about 85 degrees clockwise from the keying pin on the back of the lens as viewed from the rear.

If your lens aperture ring is set to "A" on the Carl Zeiss, then this pin will lock in the high position and prevent the lens from mounting. Move the aperture ring to the widest aperture setting - eg f3.5 or lower number. This should release the pin to move back into the housing and allow the lens to mount.

There appears to be some interaction with a lever which limits the automatic aperture actuation, probably a manual over-ride function

Another possible cause may be that you may be attempting to mount the lens 1/3rd to 2/3rd of a turn around from its normal mounting position.

Quyen's mount permits this with the Nikon lenses. The normal donkey trap of short and long cutouts doesn't always work. If this is happening, the key on the lens body will sit high because there will be no matching hole in the Letus mount face.

With Quyen's Canon mount implementation, the mount appears to be fine in this regard so my best bet is that the mechanical signal pin is your problem.

The lenses which move freely probably have neither a locating pin or mechanical signal pin or the locating pin may be spring assisted and capable of being released by another matching pin on a particular camera body model.

I don't know enough about Canons so do not regard my comments as authorative.

[Andrew Todd]

quyen solved my problem as always... the pin comes out if the lens is set to Auto.. i was using these lenses alot lately with my slr and forgot to take it off auto.. thanks :)