lucaas - does your aperture ring unscrew from the barrel? (don't try too hard)
I didn't think they did - but on the early RV below (courtesy of a google search) it obviously does... I wondered if your aperture ring could have been swapped at some point?
And I mentioned this above in this thread....Originally Posted by goamules
Garrett
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Here is a TTH assessory for these you don't see every day. A lens cap. And since the lens is in the rear, the cap goes on the rear, using the patented thread. I've seen one...this one I have, but I'm sure they're out there.
Garrett
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Ah, on my RVP the aperture ring / iris assembly doesn't unscrew (or doesn't want to anyway).
Anyone with historic glass knowledge?
Not just the ring; the entire barrel, just next to the lens board flange.
On mine the barrel unscrews from the very thin section containing the lens (as you say, just next to the lens board flange) but the ring doesn't separate from the barrrel.
That is correct.
Everything that has been assembled, can be disassembled. Even if they glued the iris part on....but they didn't.
Garrett
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I've started a list of RV (Rapid View), RVP (Rapid View Portrait) and CAP (Cooke Achromatic Portrait) lenses - it's at RV, RVP & CAP serial numbers.
The details have been compiled from these forum pages (and members), and trawling the web (Bill, you will see that I picked up on your post on another thread about Clarence White's RVP kept at Princeton). I am including lenses from casket sets that are a complete lens (supplied with another complete lens, usually a RR or WAR I think) but not (as yet) casket sets where there is one interchangeable barrel to make different configurations.
If you can add any please PM me, include ALL of the engraving if you could, and the max aperture as recorded on the aperture ring. A little obsessive but I'd also be interested to know if the aperture ring is (gently) removable from the barrel (not the lens section at the base), and (in the case of RVs and RVPs) how f11 is written on the aperture ring (as 11 or 11.3).
Observations
1) The VM suggests that there was a restart of serial numbers at some point. These lenses seem chronologically correct in serial number order, based on the company and location engraved on them.
2) The VM mentions that when they launched their patent squared-off thread end TTH stated that some 20,000 older TTH lenses could be updated with this feature (Am Photo 02/09/1892, p160 is the VM ref). This seems somewhat at odds with the serial numbers and date range recorded.
3) Apparently there are no surviving factory records of TTH serial numbers and dates. The Cooke (anastigmat) Portrait lens are later, so that serial number spreadsheet list doesn't help.
4) The engraved company name and location can suggest a range of years of manufacture.
I'm still intrigued by the range of Equiv Focal lengths for a given plate size, given the very apparent precision of TTH. I know nothing about lens construction, old glass etc but came across ''The Book of Photography - Practical, Theoretic and Applied' by Paul N. Hasluck (published 1907) which has some pages about lens manufacture at TTH. The book is around 880 pages so I've extracted the relevant sections into a subset - it's also shared from Google Drive as Lenses: Their Construction. No doubt methods and techniques will have been honed but they can't be that far from those used when these lenses were made.
A very good point. A premise I often use myself, as I'd far rather take something apart and repair it than buy a new one (especially if the item in question is old and well and solidly made).
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