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Audax2
Tinkerer
Username: Audax2
Post Number: 1
Registered: 07-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 04, 2007 - 07:04 pm: | 
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I was once shown how to open shutter blades fully on a Canon FD, when the lens is off the camera, by pressing down on one of the small pins at the back and moving one of the two protruding "blades", or whatever they are correctly called. The point, of course, is to make it easy to examine the lens for fungus, scratches and dust.
The problem is that I've forgotten how to do it. Can anyone remind me?
Thanks
Allan |
Fiftyfifty
Tinkerer
Username: Fiftyfifty
Post Number: 17
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 04, 2007 - 11:45 pm: |
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You can open the shutter blades by pressing the little stud on the inside of the mount near the top,this is on the spring not the locating pin, this will work on Breech mounted lenses but not on the newer ones.
I use an old lens mount taken of a scrap camera, this will work on all FD mounts, you may be able to cut the end out of a rear lens cap to do the same thing.
Hope this helps.
Doug |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 316
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 05, 2007 - 03:40 pm: |
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Perhaps the easiest way may be to put the lens on a body and open the shutter on the B setting to inspect the lens. |
Lucas
Tinkerer
Username: Lucas
Post Number: 20
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 06, 2007 - 12:05 am: |
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I use a rear lens cap with the center cut out. You just put the cap on the lense and you can inspect it for fungus or sticky irisblades.
Has saved me from buying dud objectives more than once, and fits easily in your pocket when roaming the fleamarket. |
Charlie
Tinkerer
Username: Charlie
Post Number: 81
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 06, 2007 - 05:50 am: |
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Just for clarity for people searching archives in the future I believe we're talking about diaphragm blades, not shutter blades. These lenses usually mount on a camera with a focal plane shutter which is in the camera body and doesn't have any blades. |
Audax2
Tinkerer
Username: Audax2
Post Number: 2
Registered: 07-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 07, 2007 - 05:47 pm: |
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Thanks to everyone for their helpful replies.
Charlie is correct : I did mean to say "diaphragm" blades.
Since my original post, I have worked out what I used to do: see below.
Opening the diaphragm blades on a Canon FD bayonet fitting lens with lens off camera.
Place the lens front down with the red dot on the back at 12 o’clock.
Note the following parts:
(1) A small pin to the right of the red dot at about 12.15 pm (Pin 1).
(2) A second small pin at about 4 o’clock (Pin 2).
(3) A vertical blade protruding from the inner ring at 6 o’clock (Blade 1).
(4) A second smaller vertical blade protruding from the inner ring at 10 o’clock (Blade 2).
(5) The lens release button on the lens barrel.
To open the diaphragm blades fully, proceed as follows:
(1) Put gentle clockwise pressure on blade 2.
(2) Push down on pin 1, with a very small screwdriver, or something similar, while holding the pressure on blade 2. The pin should stay down.
(3) Then press down on pin 2, and while holding it down, put gentle clockwise pressure on blade 2 again. The diaphragm blades will open fully.
To close the blades, proceed as follows:
(1) Press the lens release button inwards, and while holding it in position, push blade 1 in an anti-clockwise direction. The diaphragm will shut.
Thanks
Allan |
Glenn
Tinkerer
Username: Glenn
Post Number: 159
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 07, 2007 - 06:16 pm: |
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Yes, the above sequence will operate the diaphragm mechanism. However the use of a modified rear cap, as suggested by Lucas, is far simpler and does not risk damaging the rear element if the screwdriver slips. The correct 'tool' for the job is the Canon FD Macro Lenshood. This in fact, just looks like a rear cap with the centre removed, but is used when the FD lenses are reversed for bellows use. |
Audax2
Tinkerer
Username: Audax2
Post Number: 3
Registered: 07-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 07, 2007 - 10:43 pm: |
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I was going to try Lucas's method. I tried it first by putting a rear lens cap on, and observing from the front what happened. The diaphragm blades did not move at all, so I must be missing something here.
Allan |
Lucas
Tinkerer
Username: Lucas
Post Number: 21
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 09, 2007 - 01:08 am: |
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The original Canon FD rear lense caps have a stop you need to remove so the cap goes on untill you hear it lock. The third party cap I have converted did not have a stop maybe that is the problem. On my 50mm FD lense as I put on the modified rear lense cap the blades open all the way. You select a diaphragm value of your choice and if the lense is ok the blades will close and open accordingly as you manipulate the lever that protrudes most.
If you have an old FD lense with the silver ring nothing happens as you put on the cap, but the blades should move when the diaphragm is not set to its most open setting (3.5 or 2.8 depending on the lense) when you manipulate the lever.
If you have a lathe or acces to one, the conversion of a rear body cap takes about two minutes. |
Glenn
Tinkerer
Username: Glenn
Post Number: 160
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 09, 2007 - 03:56 pm: |
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The cap for the original breech-lock lenses does not have the stop on the cap lugs. The lugs are chamfered to allow the breech ring to grip and hold the cap. You will find that a well used cap can be inserted in a new FD lens bayonet ring and fully turned to activate the release button. The ramp on the lugs can be filed down if the fit is a bit tight. However this cap does not have the finger grip serrations around the outer circumference, so is not an ideal candidate for modification. The Canon cap for the new FD lenses has the finger grip and the lug stops can easily be cut off with a Stanley knife. The knife can also be used to cut out the end of the cap.
I think third party caps are/were produced to fit both breech and new FD lenses. Hence all the examples I have seen have the finger grip serrations but no stops on the lugs. |
Petercat
Tinkerer
Username: Petercat
Post Number: 11
Registered: 01-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 05, 2007 - 01:59 pm: |
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I just gutted a cheap 2X converter. Works well and the pins are easy to reach. |
