Cooke Lens on a Graflex RB Series C

[Fotoguy20d]

Can anyone tell me how this lens is mounted to the board? I see what looks like a retaining ring behind the aperture assembly. Does the entire lens simply unscrew from this ring? I was able to remove the front glass from the aperture but everything else is securely stuck in place. Except that the rear glass needs to be cleaned, it's in great shape so I'd really like to remove it and clean it up. Also, what's the optical construction - looks like 4 elements in 4 groups.

Thanks,
dan

[Louis Pacilla]

If you could add some photos of the lens/lens board it would help us help you. By the sounds of the construction your lens is a Cooke Aviar.

[Fotoguy20d]

From what little I could find, I think it's a Series X. Its the only lens that comes with a Series C, the 6.5" f2.5. It doesn't look unlike the one shown, though. Still, I'm not sure if it's on there tight or I'm pushing on the wrong place. I read that these are magnesium and corrosion prone but it's very clean and the aperture blades turn freely so I suspect it's just on tight and has been there for a while.

Dan

[Louis Pacilla]

OK My bad. I was not paying attention when I posted the earlier. would still like to see a few photos of the lens so I can get an idea what the trouble may be.

Try this

[Fotoguy20d]

I shot a few photos last night. The front cell will unscrew from the aperture section. The rear cell doesn't unscrew, and the aperture ring doesn't unscrew either. I don't know what's supposed to release vs what's stuck from being there for 80 years, vs just snug and there's nothing to grab onto in that little space.

Thanks,
Dan

http://farm9.staticflickr.com/8330/8451312034_236ca8a18f_b.jpg (http://www.flickr.com/photos/52276513@N03/8451312034/)
P1010091 (http://www.flickr.com/photos/52276513@N03/8451312034/) by Fotoguy20d (http://www.flickr.com/people/52276513@N03/), on Flickr

http://farm9.staticflickr.com/8323/8450224369_4988c7b5de_b.jpg (http://www.flickr.com/photos/52276513@N03/8450224369/)
P1010092 (http://www.flickr.com/photos/52276513@N03/8450224369/) by Fotoguy20d (http://www.flickr.com/people/52276513@N03/), on Flickr

http://farm9.staticflickr.com/8046/8450224329_12433c7162_b.jpg (http://www.flickr.com/photos/52276513@N03/8450224329/)
P1010094 (http://www.flickr.com/photos/52276513@N03/8450224329/) by Fotoguy20d (http://www.flickr.com/people/52276513@N03/), on Flickr

[jocl123]

You just unscrew it. It is only stuck.
The lens flange can be then screwed off the Graflex.
Had one of those two years ago.

[IanG]

The only question is where's the f-stop control ?

While both my Cooke lenses unscrew simply I have two Aldis lenses that rotate in their mount to change the aperture but the pin that controls it is part of the camera (an Ensign Reflex) and needs removing to swap the lens.

Ian

[Fotoguy20d]

Ian,

from what I can see, the aperture is controlled by rotating the front element. I'm not sure that's the intention, but it works (as long as you don't rotate too far and break the lens element free from the mounting ring).

dan

[IanG]

Dan, all my sunken mount lenses rotate to control the aperture, two have lugs others you rotate the front which gets worn. Most uscrew if you rotate too far but two use a pin in the body to connect to the aperture mechanism.

My guess is yours should just unscrew from the mounting ring.

Ian