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Cooke Triplet 5 3/4" (146mm) f/4.5 from Graflex
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PostPosted: Tue Jan 25, 2011 5:27 am    Post subject: Cooke Triplet 5 3/4" (146mm) f/4.5 from Graflex Reply with quote

This is the lens that came on my RB Tele Graflex



It is of course a triplet, a Cooke triplet like millions of others, but this is a Taylor, Taylor Hobson Cooke, Cooke triplet ! As best I can tell it dates from about 1919-1920. Kodak, which owned Graflex at the time, sold these as a premium lens option on the Graflex and Graphic cameras. The lesser cost lenses were Kodak Anastigmats (maybe triplets also?) and Bausch&Lomb Tessars. Its funny that a triplet was considered a superior choice to a Tessar.

5 3/4" is an odd focal length even for US/UK cameras. I believe this was required by the need to clear the mirror plus the extra depth of the revolving back on the 3 1/4"x 4 1/4" (quarter-plate) Graflex SLR. This does seem to be the shortest focal length that will give infinity on that camera. A side benefit of the longer length is that this lens will cover 4x5 with some room for movements.

I have disassembled and cleaned the lens, which was in very good shape, except for the unfortunate fact that the aperture ring is frozen. I have been unable to loosen it so far, and I don't want to ruin the finish on the lens barrel. It seems that Cooke barrel lenses often have this problem, and it is said that their barrels can be fragile.

I mounted it as usual on a drilled plastic M42 lens cap and put it on bellows. I have a very good slip-on hood that fits perfectly over the barrel, so there were no issues there.

Performance is mixed. It is not really sharp at f/4.5, but it is more than good enough for large format work I think. Any modern (in the last 50 years) 135mm lens for SLR's will probably do better at f/4. But none of those will cover 4x5 of course. I have also had better results from several large format Tessars - Bausch&Lomb, Zeiss, Ilex, etc., so I don't see any superiority in this Cooke. But maybe I have not precisely reassembled it, I believe Cooke was quite particular about element spacing. It does give a rather different effect that I can't quite describe.

All shot at f/4.5 -





















The bird -



Crop -



PostPosted: Tue Jan 25, 2011 8:41 pm    Post subject: Reply with quote

Nice old performer. It have own charm. That horse pic looks great to me. Good shadows and very well done handled by the lens.
What camera did you use for that samples?


PostPosted: Tue Jan 25, 2011 9:12 pm    Post subject: Reply with quote

Goes to show that good grinding is better than a picture Wink when it comes to lens making at least Laughing

It's amazing how well this old lens does with a fraction of its designed image area


PostPosted: Tue Jan 25, 2011 9:19 pm    Post subject: Reply with quote

The camera is a Pentax K-x

I don't know if its good grinding. I think the usual Tessar from those days could probably do better even wide open. I have a bunch of slightly later Tessars that for sure can.


PostPosted: Wed Jan 26, 2011 12:27 am    Post subject: Reply with quote

You get some beautiful result from this old lady. Congrats!


PostPosted: Tue Jul 02, 2013 9:03 pm    Post subject: Reply with quote

Pretty nice, just a tad on the soft side, but i expect stopping it own will make it very sharp, I have the same lens and mine is stuck at f8, I find it to be a sharp old thing.


PostPosted: Tue Jul 02, 2013 9:32 pm    Post subject: Re: Cooke Triplet 5 3/4" (146mm) f/4.5 from Graflex Reply with quote

luisalegria wrote:
.... maybe I have not precisely reassembled it, I believe Cooke was quite particular about element spacing.


I once did some ray-tracing of a Cooke triplet and the lens separation is indeed critical. But of course, this is true with any lens design. With lenses of this age, maybe there was some element of fine tuning each lens to get the best performance. A premium lens like the TTH could have been individually tweaked. Production engineering in those days would not have the tolerances we can get now or even got in the 1960's. Thus, simply fitting the glass elements back in their rings may not give the optimum result. I am speculating somewhat.

Lovely results, nonetheless.

Mark