1/4" 20t or 3/8" 16t

Discussion in 'Large Format Cameras and Accessories' started by Curt, Jul 18, 2010.

  1. Curt

    Curt Subscriber

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    Does anyone know, I'm not sure this has been addressed here, why the European thread standard for camera sockets and tripod studs are 3/8" 16 threads per inch while US is 1/4" 20 threads per inch?

    Doesn't Europe use the Metric System for fasteners? Why aren't the tripod sockets say 12mm in Europe?

    Curt
     
  2. Ian Grant

    Ian Grant Subscriber

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    Both sizes are European standards, neither originated in America.

    1/4" 20 threads per inch tripod sockets must have a very close Metric equivalence, as must the 3/8" 16, both were common on pre-WWII German cameras, and Britis camera. The 3/8th thread was more common on larger cameras,

    My 2 Patent Etui's are the larger thread and one came with a pre-WWII tripod the ball head being 3/8th thread.

    Both sizes are BSW - British Standard Whitworth, and are accepted as the international standards for tripod mounts.

    Ian
     
    Last edited by a moderator: Jul 18, 2010
  3. RalphLambrecht

    RalphLambrecht Subscriber

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    Curt

    I think this is more a small vs large camera issue. Both threads are used in Europe and in the US. I'm not aware of any metric tripod threads, probably for historic reasons.
     
  4. Ian Grant

    Ian Grant Subscriber

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    It may also be because until 1841 there was no standard of thread sizes, Whitworth's standard was the first.

    Ian
     
  5. Curt

    Curt Subscriber

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    American national standard for photography (cameras)--tripod connections for heavy-duty or imported cameras (3/8-inch-16 thread with adapter for 1/4-inch-20 tripod screws)
    Type of Work:Non-dramatic literary work
    Registration Number / Date:TX0002049520 / 1987-04-09

    Date of Publication December 7, 1983

    Date of Creation:1983

    Title:American national standard for photography (cameras)--tripod connections for heavy-duty or imported cameras (3/8-inch-16 thread with adapter for 1/4-inch-20 tripod screws) : A N S I PH3.102-1983.

    Basis of Claim:New Matter: "new, revised, and updated material throughout."

    Previous Registration:tongue:rev. reg. 1953 as American national standard tripod connections for heavy-duty or European cameras, 3/8-inch-16 thread with adapter for 1/4-inch-20 tripod screws, A N S I PH3.7-1952.

    Variant title:American national standard for photography (cameras)--tripod connections for heavy-duty or imported cameras

    Other Title:American national standard tripod connections for heavy-duty or European cameras
     
  6. Curt

    Curt Subscriber

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  7. Ian Grant

    Ian Grant Subscriber

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    That''ll be already superseded by later ISO standards :rolleyes:

    The US adopted the Whitworth standard back in the 1840's, as in the UK other standards also came into use later.

    These tripod standards are as old as photography, and no ASA, ANSI,DIN, BS or ISO has actually changed the standards, just re-witten the same thing with a new standard number.

    Ian
     
  8. lxdude

    lxdude Member

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    I'd say it's to handle the weight of the surveying equipment and make sure they are securely attached. Tripods are usually carried from position to position with the equipment attached.
     
  9. bdial

    bdial Subscriber

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    Or else, it's to frustrate photographers looking for sturdy, cheap tripods at the home centers.:wink:
     
  10. RalphLambrecht

    RalphLambrecht Subscriber

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  11. Ian Grant

    Ian Grant Subscriber

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    That makes sense.

    That accounts for why my 9x12 Patent Etui's - the smallest, lightest LF cameras ever made use 3/8" tripods threads, and my 10x8 Agfa Ansco Commercial View camera uses 1/4" :D

    Ian
     
  12. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I don't think that historically it's a size and weight consideration. My tiny Voigtlander Perkeo II 6x6 folder has a 3/8" socket, and that's pretty common on other 1950s European medium format folders. My 1890s 11x14" American Optical field camera is 1/4".

    Of course with a 3/8" socket, it's easy to add a bushing for 1/4", while the reverse adapter doesn't usually provide as good a support, so I would think that that would be another factor.
     
  13. RalphLambrecht

    RalphLambrecht Subscriber

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    I'm not aware of any modern 35mm camera with a thread larger than 1/4". Most MF cameras I'm familiar with have 1/4" and/or 3/8", and many LF cameras have 3/8" with a feature to insert a 1/4" thread. Of course, there are always exceptions (and people eager to point them out), but their is an obvious trend of size and weight towards larger threads, and it makes sense to use a larger thread for an increased holding-power requirement. This seems to be supported by a historic trend with older (and larger) cameras having larger threads, because I haven't seen any 1/4" threads prior to the introduction of the Leica.

    Here is a quote from Wikepedia on the subject:

    http://en.wikipedia.org/wiki/Tripod_(photography)

    The historic standard threading for the bolt that attaches the camera to the tripod is 1/4"-20tpi (threads per inch) British Standard Whitworth (Whitworth or BSW) for smaller cameras or 3/8"-16tpi BSW for larger cameras and pan/tilt heads.
     
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  15. Ian Grant

    Ian Grant Subscriber

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    The 1890's British Quarter plate camera that I've just restored has a 1/4" thread as do some of my other early cameras, but my pre-WWII German cameras all use 3/8" except for my Leica. I think my first Rolleicord was 3/8" as well. It may well have been a preference in the German camera industry.

    Mamiya certainly used 3/8 on some of their MF cameras up until the mid 70's.

    Ian
     
  16. NormanV

    NormanV Member

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    My Zork C has a 3/8 thread
     
  17. mike c

    mike c Subscriber

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    My 500cm has both 1/4,3/8 thread.
     
  18. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    What's the shear strength of a 1/4" steel or even brass bolt? Plenty to hold just about any camera that one person can lift, I suspect, with room to spare for leverage with long lenses. It seems logical to think that we need a larger bolt for a bigger camera, and contemporary large format camera makers tend to follow that reasoning, but I suspect that there are more arbitrary factors (like regional norms) at play in the history of the standard thread sizes, considering that the larger thread really isn't necessary at all for anything short of a camera that could also pass as furniture.
     
  19. Ian Grant

    Ian Grant Subscriber

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    Another factor David is that many older plate camera's had their own detachable legs, and never had a tripod mount at all.

    Ian
     
  20. Roger Thoms

    Roger Thoms Subscriber

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    Don't know, but I choose 3/8x16 for my pinhole camera, certainly don't want it flying off the tripod. Biggers better right.

    Roger
     
  21. Ian Grant

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    Many tripods don't (& can't) use a 3/8" thread these days and adding an adaptor is adding a weaker link.

    Ian
     
  22. Steve Smith

    Steve Smith Subscriber

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    The 1/4" Whitworth thread is very similar but not identical to the American 1/4 - 20 thread. They are both 20 threads per inch but there is a five degree difference in cutting angle.

    In most cases they are interchangeable but if you are making something yourself which is a bit heavier than a standard camera, it would make sense to get a proper Whitworth thread so you get full face to face contact with the threads rather than an edge contact only.


    Steve.
     
  23. Ian Grant

    Ian Grant Subscriber

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    A US 1/4" nut won't fit a 1/4" Whitworth bolt, it'll bind. But a US 1/4" bolt will fit a 1/4" threaded bolt or tripod socket, butb not a good idea for a heavy camera.

    Ian
     
  24. Steve Smith

    Steve Smith Subscriber

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    I was thinking about the DIY camera makers who use a 1/4 x 20 threaded insert as a tripod mount. It does work this way round and although not ideal is o.k. for lightweight cameras. However, the other way round will not fit too well as you rightly point out.


    Steve.
     
  25. Jan Pietrzak

    Jan Pietrzak Member

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    I have number of Ries tripods, 'A's 'B's 'C's Junior's you get the point. The head for the 'A' is 3/8ths I use it for the 11x14 and 8x10. The model 'B' great size is for the 5x7 and 4x5 it has a 1/4-20 head, just fine. The small stuff is all 1/4-20 on all the rest. This just works for me.

    Jan Pietrzak
     
  26. ac12

    ac12 Member

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    For strength the other factor would be the flat bearing area on the bottom of the camera, and the matching area on top of the tripod. The larger the surface, the smaller the lever factor against the tripod screw, because the edge of the bearing surface is farther from the screw.