Controlling the Apature on the SLR Lens
 

I just received my Letus35 XL.

In testing it, I have an image in the viewfinder. The Letus35 XL is properly mounted to the Canon XL H1.

When I mount a Canon FD Lens to the front of the Letus, the manual apature controls on the lens do not change the iris.

The lens mount has a Canon FD side and a Nikon side. The lens mounts snugly (fits well) into the mount.

When the lens is mounted the iris is fully open. It remains fully open no matter what manual apature is selected on the lens.

If I have the lens properly mounted on the Letus35 XL lens adapter ring, but without the adapter ring mounted on the front of the Letus, then I can manually move one lever on the lens and then the lens's iris properly closes down to the selected apapture.

I have tested this with 3 separate geninue Canon FD lenses: a 50mm f1.4, a 50m f1.8, and a 24mm f2.8. I am awaiting delivery on other lenses.

It seems that I must be making a "new user" mistake, or I have a misunderstanding.

I assumed that I would be able to change the apature (iris) on the lens by just moving the apature control on the lens.

Any assistance or advice will be greatly appreciated.

Dan

I have Nikons so don't take my word for it on Canons. I believe the workaround is to make small plugs or wedges and prop the little lever on back of the Canon lenses into the open position. I understand that the iris then moves with the movement of the aperture ring.

Check to see if the movement of the aperture ring is directly linked to the lever. If this linkage is firm and not via an over-ride spring, forcing the aperture ring may bend something.

If, once you have selected an aperture setting and you change it and the iris holds back onto the first setting it may be necessary for you to use a small spring or band to apply pressure to the aperture lever.

Stick with your Canon lenses. (The reverseable mount is not so good with the Nikons and it is better to use the purpose built Nikon mount.)

Dear Bob,

Thanks for the advice. I had no idea that I would have to make some shims or wedgies.

On my cheaper lenses, I used JB weld to adhere the lever to its open position and a rubberband to hold it in place while it dried. Probably not a good idea for more expensive lenses.

Dear Ben,

Thanks for the information.

I think I will make something out of the super strong plastic that protect many items these days, these are the packages that are almost impossible to open! If that does not work, I will try using a credit card.

I made something out of cork last night that worked, but I do not want to use it permenently.

Dan.

There's a bit of Letus35XL footage in this clip.

http://www.youtube.com/watch?v=NXyJZHPYPP0

Wide master was Sony Z1P, the 2nd wide was Canon XL1, roving close-up was Canon XL2 with Letus35 and f1.4 85mm Nikon. The very first shot through the booth window was FX1 with AGUS35.