Canon FD Lens question... - DPChallenge Forums

Canon RF 24-70mm f/2.8 L IS

10/01/2006 10:58:16 PM · #1

I have an old Canon lens I want to use for reverse macro shots. When off the camera the aperture is stuck about half way (f11?) Is there a way to get the app to open to the full 1.8 of the lens when it is off the camera?

I am willing to sacrafice the lens in order to do this!

KS

kirbic

Canon EOS R5

10/01/2006 11:19:04 PM · #2

If I'm not mistaken, FD lenses had a mechanical actuator that transferred movement from the camera to the lens, thus changing the aperture. If you can figure out how to actuate it, you should be able to open up the aperture.
I'm not so sure on the metohd of actuation, I've never played with any FD bodies/lenses

MadMan2k

Sony Alpha a6400

Tamron 70-180mm F/2.8 Di III VXD

10/01/2006 11:31:46 PM · #3

When it's on the camera can it open up? Does the camera have a DOF preview button? If so, try holding that down and taking the lens off at the same time, hopefully it'll stay at the aperture it was set at. This is the method people sometimes use for manual extension tubes to stop down lenses, maybe it'd work the other way?

10/01/2006 11:35:28 PM · #4

I do have access to an AE1 that I can try the DOF button however, shouldn't I be able to open and close the app with lens off the cam?

The lens has two metal "sliders"...one moves freely and the other stays in one spot...unable to move. I think these "sliders" have something to do with it!

Originally posted by MadMan2k:

Canon RF 24-70mm f/2.8 L IS

10/02/2006 10:45:11 AM · #5

The DOF button worked on cam...tried to remove lens with button engaged but the Aperture shut as I took the lens off!

Any other suggestions?

Skid

kirbic

Canon EOS R5

10/02/2006 11:04:50 AM · #6

The "sliders" are the key. Mounting the lens unlocks them. You need to figure out how that happens, and actuate the unlocking mechanism manually, then move the correct slider to the "full open" position and lock it there. You could just glue it in place, since you're not worried about using the lens again for its intended purpose.

10/02/2006 11:08:15 AM · #7

I hear ya bro...I have the lens here at work with the body and can see that when I push the "DOF preview" slider on the camera it is pushing the seemingly "un-slidable" slider.

I can't figure out how to slide that slider with the lens off the camera. I poked and pulled every which way...I'll keep trying!

Thanks,

Originally posted by kirbic:

10/02/2006 02:29:30 PM · #8

Ok...listen carefully because I searched high and low on the internet for the solution. I did not find one....however, I figured it out on my own...with the guidance of others on this site.

On my Canon f1.8 50mm FD lens there is a ring with three tiny philips screws. Place lens face down on table and unscrew each screw.

After screws are out:

Using a small flathead screwdriver or knife, simply pry up the round silver piece that the screws were "holding in".

With that piece out, you should now be able to "spin" the inside of the lens and "SEE" the diaphram moving.

Get the diaphram to where you want it and you're almost done. I chose the fully open f1.8 .

I'm not sure if mine "clicked" into place or not but just fiddle with it.

When the diaphram is open to where you want it, put the silver piece back in. You may have to rotate until you find how it fits.

Reinstal screws!

For reference:
I noticed that on the silver button on the lens that you have to press in order to get the lens off the camera is now in a permanant "raised" position, like it thinks it is on the camera.

BTW...this process is reversable, so you are not ruining any of your old lenses!

Now with this lens "open" I have a much eaisier time using it reversed on the end of my 60mm and 105mm. I am no longer looking through a "tunnel" at my subject, but can see it with ease!

I'll post some shots later tonight.

Kenskid

Message edited by author 2006-10-02 18:01:35.