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Thread: Rapid View Portrait (RVP) Pictorial lens

  1. #91

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    Re: Rapid View Portrait (RVP) Pictorial lens

    I have it on good authority that the term "three strikes, you're out law" was coined from the "three turns and it's out" TTH patented thread.

    Did you know Dallmeyer also had standardized threads in their flanges? I think several other British lens companies did too. I have a lensboard with a flange on it that will hold three of my Dallmeyers, a portrait, a RR, and a wide angle.

  2. #92

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    Re: Rapid View Portrait (RVP) Pictorial lens

    As I understand it, TTH were (at the very least) 'early adopters' of the RPS standard for lens screw mounts, and the thread for this smaller size will be 24 TPI (threads per inch) Whitworth.

    The Early Photography site (here) says:

    The usual method of attaching the lens to the camera was a screw thread, standard thread sizes were proposed by the Royal Photographic Society (RPS) which were adopted by some manufacturers including Taylor, Taylor & Hobson (T.T.H.) and, from around 1890, Ross. The RPS sizes, first proposed in 1881 and later modified, used a Whitworth Angular thread, for small diameters 24 threads per inch was used, for sizes above 3" 12 tpi. [Ref 2]

    An important development was made by T.T.H. in 1892 by chamfering the start of the thread which made picking up the thread much easier. [Ref 3]


    [Ref 2 is 'BJA 1900, 1123. BJA 1902, 1125a.' (British Journal Photographic Almanac)]
    [Ref 3 is 'BP 3019/1892' (maybe 'BJP' ? British Journal of Photography ?)]

    Here I think is the original proposal for the standard in the RPS archives:
    https://archive.rps.org/archive/volu...ume-22-page-91

    Working examples of the flanges and screws have been manufactured (by Whitworth, and Ross & Co):
    https://archive.rps.org/archive/volu...ume-24-page-39

    The flanges get an honourable mention in the Financial Statement:
    https://archive.rps.org/archive/volume-24/719087-volume-24-page-42

    etc. etc. A search for 'flange' in the RPS archives from 1882 onwards will bring more results...

  3. #93
    Mark Sawyer's Avatar
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    Re: Rapid View Portrait (RVP) Pictorial lens

    Most lenses have just under a quarter-inch of threading for the flange. For Cooke's three turns, that's about a 13 tpi thread. (A 12 tpi thread would be exactly a quarter-inch of threads.) That math applies to all diameters.

    I really like it; three turns is plenty, the coarser threads are strong, and you have to be trying pretty hard to cross-thread.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  4. #94

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    Re: Rapid View Portrait (RVP) Pictorial lens

    Quote Originally Posted by peter brooks View Post
    As I understand it, TTH were (at the very least) 'early adopters' of the RPS standard for lens screw mounts, and the thread for this smaller size will be 24 TPI (threads per inch) Whitworth.
    Wray too adopted the 'RPS Standard flange threads" but it appears that the 'standard' may not have been as 'standardised' as it should have been. From my reading and practical experience there seems to have been variation even in the 'standard' threads. I seem to remember reading about meetings between the various manufacturers where some progress was made but complete standardisation may not have been thoroughly achieved. Early Wray lenses nearly fit later' standard' flanges but don't and some later lenses seem not to either. I think that thread tolerance and interpretation of thread parameters remained a problem.

  5. #95

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    Re: Rapid View Portrait (RVP) Pictorial lens

    Quote Originally Posted by Mark Sawyer View Post
    ... Even the most modern lf lenses seems a bit less "civilized" by comparison...
    Quite right... I'm thinking that the delicious fit of TTH lenses to their flanges is in part due to the use of the Whitworth thread (the story of which is itself interesting - https://en.wikipedia.org/wiki/Britis...dard_Whitworth) but also to the extrordinarily precise engineering carried out at the company. The document I mentioned in post #69 (Lenses: Their Construction) describes them using gauges to work to tolerances of 1/1000 inch (pages 9 and 10 of the 14).

    Quote Originally Posted by goamules View Post
    Did you know Dallmeyer also had standardized threads in their flanges?
    Do you have any Dallmeyer lens that fit TTH flanges? Or vice versa? Just wondering

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