Taylor Hobson and Cooke lens repair

[Tracy Smithson]

I recently purchased a Taylor Hobson and Cooke Series II lens 15 inch f/4.5. It has several aperture blades out of alignment. I have repaired this problem with other much smaller lenses. However, with this one I cannot figure out how to get at the blades after removing the rear lens element and the retaining band. Can anyone tell me how to proceed from this point to gain access to the blades for re-alighnment. I would appreciate any help.

[martin vollert]

hi tracy,
i'm in the position to purchase a 15inch series 2A f3.5 cooke lens. can you tell me how much you paid for yours, so i can make an apropriate offer.
thank you very much,
martin vollert
vollert@maui.net

[Tim Deming]

I'm not familiar with this particular lens, but in other large lenses I've worked on, the retaining ring for the aperature blades unscrews for removal. There might also be a retaining screw or pin holding it in place. Some good close-up pictures of the aperature mechanism from both sides might help get better advice. There is the possibility that the mechanism is welded in, but usually older lenses are very servicable

cheers

Tim

[David Vickery]

I am assuming that your lens is in a barrel.
I am not directly familiar with that particular lens but it should not be a problem to get it apart.
You may have to take out the front group and you may also have very tiny set screws in the barrel that may even be covered by paint or lacquer.
There will probably be a plate or ring that is held in with small screws that you get to from the front inside.

[Terry Costard]

Yes I too have the same lens with the same problem. To access the blades a rear retaining ring adjacent to the lens board side of the lens unscrews, I had to use a large pair of rubber gloves with great traction and plenty of strength to free it up, careful not to touch the blades. Clean the blades with white petrol, I then wipe the blades with a small amount of silicon grease and then polish the grease off, before assembly.
Hope this helps