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Thread: 5x7 film dimensions in mm (and relationship with GG)

  1. #1

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    5x7 film dimensions in mm (and relationship with GG)

    Hi,

    Just to firstly note, I have not yet shot a piece of film on my new second hand norma, so go easy on my ignorance!

    I have broken my ground glass, and am looking to replace, and I'm wondering why my ground glass is 5"x7" in total size, but the painted on framing rectangle is only 170x120 millimetres (smaller than 5"x7" by about 4-5mm on each side).

    So I'm wondering.. what is the actual size of standard 5x7 film? And how does this translate to the ground glass? Would the image be larger than the framing rectangle dimensions mentioned above?

  2. #2

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    Re: 5x7 film dimensions in mm (and relationship with GG)

    I also have a 5x7 Norma (bought new around 1970) with the original groundglass. Looking at the ground glass there is an outline for 5x7 framing as well as outline for 13x18cm film (somewhat smaller than 5x7) that is more popular in Europe. Looking in my archive of communications with Ilford, I found their film dimensions for cutting FP4+ and HP5+ (which I suspect is very close to other manufacturers' films) since they all should fit properly in the correct sizes of film holders. Here is Ilford's data:

    Our finishing cutting dimensions for 5x7" film are:

    Nominal (cm)
    12.7 x 17.8

    Aim (mm)
    125 x 176.4

    Tolerances (mm)
    +/- 0.8 both long and short sides

  3. #3

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    Re: 5x7 film dimensions in mm (and relationship with GG)

    Quote Originally Posted by Jerry Bodine View Post
    I also have a 5x7 Norma (bought new around 1970) with the original groundglass. Looking at the ground glass there is an outline for 5x7 framing as well as outline for 13x18cm film (somewhat smaller than 5x7) that is more popular in Europe. Looking in my archive of communications with Ilford, I found their film dimensions for cutting FP4+ and HP5+ (which I suspect is very close to other manufacturers' films) since they all should fit properly in the correct sizes of film holders. Here is Ilford's data:

    Our finishing cutting dimensions for 5x7" film are:

    Nominal (cm)
    12.7 x 17.8

    Aim (mm)
    125 x 176.4

    Tolerances (mm)
    +/- 0.8 both long and short sides
    Strange. So both of those are actually larger than the dimensions of the framing rectangle on my Norma GG. On my GG, there is only only one frame which has 5x7 and 13x18 printed alongside it.

    I'm just wondering whether there is any point is getting a framing rectangle put on if it's dimensions are inaccurate anyway. Here's is my GG. Not sure if it is even an original I suppose. Click image for larger version. 

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  4. #4

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    Re: 5x7 film dimensions in mm (and relationship with GG)

    MB, I owe you an apology. My GG looks just like yours; I had added some additional lines on mine inside the Sinar lines for another purpose. I use 5x7 film, but I've heard that 13x18 film has different dimensions and require different film holders; I can't recall the differences at the moment. I do know the differences are small and do make a difference. I'm going to track it down somehow.

    Edit: Have a look at Post #8 in this link:
    http://www.largeformatphotography.in...ighlight=13x18

    So it seems there's no easily discernible difference in the framing of either image, which explains why Sinar's GG shows only one framing for either 5x7" or 13x18cm film. But the two film cut sizes are different enough to cause problems and should be used with the appropriate holder size.

  5. #5

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    Re: 5x7 film dimensions in mm (and relationship with GG)

    5x7" film is 127x178mm, 13x18cm film is 130x180mm. Yes, you need different holders (same outside dimensions, different inside dimensions). Please remember that the film can't be exposed up to the edges. It has to be be held in place by guard rails. This might be the explanation for your your (smaller) frames on the GG. They mark the usable film size.

  6. #6

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    Re: 5x7 film dimensions in mm (and relationship with GG)

    Quote Originally Posted by Jerry Bodine View Post
    MB, I owe you an apology. My GG looks just like yours; I had added some additional lines on mine inside the Sinar lines for another purpose. I use 5x7 film, but I've heard that 13x18 film has different dimensions and require different film holders; I can't recall the differences at the moment. I do know the differences are small and do make a difference. I'm going to track it down somehow.

    Edit: Have a look at Post #8 in this link:
    http://www.largeformatphotography.in...ighlight=13x18

    So it seems there's no easily discernible difference in the framing of either image, which explains why Sinar's GG shows only one framing for either 5x7" or 13x18cm film. But the two film cut sizes are different enough to cause problems and should be used with the appropriate holder size.
    No apology needed, Jerry! Glad to have you helping on this.

    I've made sure that I have ordered modern 5"7" film holders (as opposed to 13x18 or half plate, which still sometimes have 5"7" at the top).

    I'm still a bit confused that the framing rectangle dimensions (170mmx120mm) seem smaller than even modern 5x7 film (127mm x 178mm quoted in link). Unless it is something to do with the projection and the position of the GG in relation to the film. Would you say that the framing rectangle on your Norma GG gives you an very accurate preview of the eventual image (in terms of image borders)?

    (I'm probably over analysing here, but I get irritated when my ordered digital prints have mms shaved off the original image!)

  7. #7

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    Re: 5x7 film dimensions in mm (and relationship with GG)

    I actually don't pay too much attention to it; I suppose if I ever found that something important on the fringe of my composition was not in the negative I'd be upset about it, but that's never happened. So I suspect it's of no concern. I usually do some very slight trimming of the final print when mounting it anyway.

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