12x16.5 cm same as halfplate?

Discussion in 'Plate Cameras and Accessories' started by Jerevan, Jan 21, 2007.

  1. Jerevan

    Jerevan Subscriber

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    Am I correct in assuming 12x16.5 cm is the same thing as the halfplate size, which has the same external size as 5x7 and 13x18? Since I've already made at least one mistake regarding inches and metrical sizes, I'll ask this time around... :tongue:
     
  2. Roger Hicks

    Roger Hicks Member

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    Half-plate = 4.75 x 6.5 inches = 121 x 165mm rounded to whole numbers. Allowing for the normal precision with which film sizes are given, especially by some Americans ('3x4 inch' for 3.25 x 4.25 inch quarter-plate), yes, you're right. I'm pretty sure that my one half-plate holder is marked 12,1 x 16,5 cm. The millimetre ain't gonna make much difference...

    Incidentally, half-plate ISN'T half of whole-plate (6.5 x 8.5 inches) -- it's half an inch (12.7mm) bigger on the short dimension -- but quarter-plate IS a quarter of whole-plate.

    Cheers,

    R.
     
  3. Jerevan

    Jerevan Subscriber

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    Thank you - in my research last night I also found there was something called "halfplate" during the first half of the 19th century, which had different dimensions (4.5" x 5.5"). The overall "logic" to the system makes me sometimes laugh, at other times sigh loudly. But given the ease with which one can cut a plate of tin or glass, it's no wonder...
     
  4. Justin Cormack

    Justin Cormack Member

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    Fuji quotes it as 118x163mm (they sell half plate Acros, just got some).
     
  5. Ole

    Ole Moderator Staff Member Moderator

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    That makes sense. Film sizes are always a few mm smaller each way than the glass plate sizes; this is done on purpose. It was originally done to accomodate the film adapter sheaths necessary to use sheet film in plate holders, and was never changed. That's why 13x18cm film measures quite exactly 5x7 inches (127x178mm), and 5x7" film is a few mm smaller...

    The same strange "half-size" phenomenon is found in metric sizes too, BTW. 4.5x6cm is one quarter of 9x12cm which is one quarter of 18x24cm, and 6.5x9cm is one quarter of 13x18cm. But 9x12cm is not half a 13x18; and nothing whatsoever is half or quarter of 24x30cm. There was also a 10x15cm size which could possibly be said to be one eighth of 30x40cm, but neither of the two fit in with the other standard sizes in any logical way.
     
  6. Jerevan

    Jerevan Subscriber

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    I looked at it, but I wasn't sure it'd fit my holders I won (purely by accident, honest!) on an auction site. Figured 18x24 film or paper would be possible to cut into two nice parts, so I'll start with some Agfa MCP I got in the closet.
     
  7. clay

    clay Subscriber

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    I hate seeing posts by annoying pedants. But since no one else will volunteer, i guess it is my turn to be one.

    <Pedantical trivia-on>
    I was surprised to find out recently that there was some difference in opinion between the French and the English over the appropriate dimensions of whole and half plates.

    Apparently, Desire Van Monckhoven in 1863 determined that the proper dimensions of whole plate was 7-1/8" x 9-7/16" and half plate should be 5-3/8" x 7-1/8".

    This is from "Traite general de photographie", 3rd edition, 1863 by way of Primitive Photography, the excellent calotype manual by Alan Greene.

    </pendantical trivia-off>
     
  8. alexphoto

    alexphoto Member

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    Hi Justin
    Where did you get your half plate Acros from?
    Alex
     
  9. Jerevan

    Jerevan Subscriber

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  10. roy

    roy Member

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    Interesting Justin, who was your source of supply ?
    Does the film fit into a half-plate film holder ? I ask this because I once bought some and the dimensions were cut to half-plate and were a couple of mm too large.
     
  11. Justin Cormack

    Justin Cormack Member

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    Yes I got mine from Unicircuits.

    I dont have a half plate film holder though (yet), only a plate holder, so I am sticking it to glass so tolerance is not so crucial. I think its the same size as the half plate film retrophotographic sell too, but I will have to check.
     
  12. Richard Kelham

    Richard Kelham Member

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    There is always some difference of opinion between the French and the English!



    Richard
     
  13. Jim Jones

    Jim Jones Subscriber

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    From the 1944 ANSI centimeter photographic dry plate specifications:
    12 x 16.5mm +/- .5mm

    From the 1951 ANSI inch size photographic dry plate specifications:
    4.25 x 6.5 +/- 1/64 (10.75 x 16.27cm +/- .4)
    4.75 x 6.5 +/- 1/64 (11.91 x 16.27cm +/- .4)
     
  14. Ole

    Ole Moderator Staff Member Moderator

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    Ye gods - that's smaller than a digisensor! :surprised: :tongue: