TT&H Cooke Anastigmat "Series III" lens with the jammed aperture. What to do?

[evgenys]

Hello friends,

Recently and by occasion I've acquired the old brass Taylor Hobson Cooke Anastigmat "Series III" 7 1/2 inches f/6.5 lens. The glass of the lens is in superior condition. In fact I didn't see such clear glasses without any disadvantages. But I can't say the same about the lens barrel which has the faulty aperture: I don't know why it was damaged, because aperture moves smoothly, but several of the leafs are jammed and some of the pivots are missing thus the leafs move incorrectly and don't form the regular circle of the aperture opening. The jammed leafs don't allow to move the aperture freely to the both ends (to fully open and to the f/64), so I could find that the only more or less right aperture opening is at f/11 (although even on this f/11 they form something like irregular figure between the circle and the ellipse).
I'd like to use this lens on my 1/2 plate camera, but I need to decide what to do with it. After some thoughs I see the following:

Get rid of this lens and find something other in the workable condition.
Use this lens at f/11 only.
Find the same lens with a dead glass (for cheap) but with the working aperture.
Remove the aperture leafs and cut the barrel to make the waterhouse stops.


I'd like to get your advices to help me to make the right decision. The questions (according to the list above) are:

Is this series of the Cooke lenses worth to use them? I searched this forum and googled the Internet but didn't find any specific, except that Series III lens is intended for the general photography (http://www.cameraeccentric.com/img/info/cooke_1/thumb/cooke_1_13img.jpg). So I guess they are good common lens without any specific features. Am I right?
Somewhere I read that Cooke Anastigmats are best performers at their closed apertures. f/11 is far from the f/64 available on this lens. So using this lens at f/11 only probably won't give me all the lens could perform, will it?
I don't know if there any good chances to get the same lens (especially with the dead glass) for the affordable price, taking into account the current "boom" prices on the old optics.
This way will restore the full functionality of the lens (at the least 90-95% of it), but will take some precision work and probably some $$. Is it worth to go this way?

Thanks in advance for your opinions.

[Steve Hamley]

5. Send lens to Carol at Flutot's or Adam at S.K.Grimes and have them fix it.

Should be about $50-75.

Cheers,

Steve

[evgenys]

5. Send lens to Carol at Flutot's or Adam at S.K.Grimes and have them fix it.

Should be about $50-75.

Cheers,

Steve

Thanks for the idea! Unfortunately I'll have to add $40 for the shipping to USA and back. In total it'll cost me $90-115. Plus the cost of the lens itself as I got it $20. In total the lens will cost me $110-135.
Is it the price of the same lens in the working condition?

[Jimi]

I'll give you $25 for the lens. :)

Seriously, though: it should be possible to remove the ring that holds the iris with the leaves, giving you a ready-made slot which you can use to insert a waterhouse stop.

[evgenys]

I'll give you $25 for the lens. :)

Seriously, though: it should be possible to remove the ring that holds the iris with the leaves, giving you a ready-made slot which you can use to insert a waterhouse stop.

Okay, I'll think on your proposal :)

Seriously: how to remove this ring? I disassembled the lens but couldn't find any screws, etc. that let me remove it. From the front of the lens there is the embedded ring which holds the middle glass element. From the back the ring which holds the back lens element looks like the solid piece of the barrel and is smaller than the aperture ring.
A bit later I'll post here a photos of the lens barrel to show you what I mean.

[Gene McCluney]

I am sure there are "some" qualified camera technicians in Russia, or continental Europe that can repair your lens.

[eddie]

use it the way it is.

you may not even notice the out-of-round iris. for $20 you can not go wrong.

let us know how you make out.

[evgenys]

Here I attached the photos of the lens barrel. I removed all glass cells. The problem is that I don't see any ways how to disassemble the barrel in its middle to remove the iris without breaking it. I can remove the rotating element of the diaphragm from the back with the pliers, but this way will totally destroy it.

[Jim Galli]

It is a very fine lens and you should definitely keep and use it. Typically somewhere in the exterior aperture ring there is a very tiny set screw. If you find it, take the set screw all the way out. Then with a little force CCW try to keep turning the ring after it passes the last number. It is on a thread and you can spin it completely off the lens barrel. When it is out of the way you'll be able to see there is a slot that could be used for waterhouse if the non working parts inside are removed. This is the cheapest solution and since the lens isn't terribly valuable, it makes the best sense. Later if you have a chance to buy an Ilex size 3 American shutter from the 1950's on Ebay, perhaps you can get a machinist to make some adapter bushings to mount the elements in a shutter. Modern shutter would have to be Copal 3 but pretty expensive. I have this lens mounted in the Ilex shutter. It is a wonderful performer and it is not necessary to stop down. It will be very sharp at f8 and f11!

[evgenys]

Jim, what surprises me is that I cannot find any screws on the aperture ring and on the exterior of the barrel on the whole. I guess that the barrel is molded thus it's impossible to disassemle it without any damage.
I think I'll break out (as the leafs are already damaged) the iris from the back of the barrel and will see what can be done to install the waterhouse stops.

[Jim Galli]

Look carefully at the black area on the ring that is the 'pointer'. Try scraping there with a knife to see if there is a screw hidden behind the paint.

[sun of sand]

What about focusing as wide open as you can get the iris
take off front element and slip in desired homemade aperture then screw back in

Like a waterhouse stop but without all the damage/potential for

Or instead of unscrewing element and having minor issues with dust
tape an aperture to the front of the lens
maybe results in less sharp photos that way but?

Free

[sun of sand]

I knew putting the aperture in front would degrade sharpness or not help with aberrations
whatever
but I don't know what exactly it does ..especially with complex lenses
I've only done this with simple achromats/doublet/meniscus types
Seems long focal length lenses don't matter as much, either
simple lenses have been sold this way and convertible lenses end up being used this way but that is a long focal length if not always a simple achromat doublet group
People say it cuts off angle of view or whatever if done with complex lenses and just doesn't work
?
I gave a quick test with an artar and works as aperture
if it cuts off field or limits movements or increases aberrations ..


I'm just saying since it seems I killed the thread

[sun of sand]

Not entirely on the subject but regarding paper aperture blades
To me they seem to be a thicker paper coated with glue

Any chance? I apply glue to homemade lens caps/shades after painting as it cuts down on the gloss of even flat paint and also provides a scratch resistant coating