Measurments of composing card?

[Clark King]

I want to use a composing card with 4x5 format, so I would need to make the card with a 4x5 in. opening right? I saw on Q's site that the opening should be no smaller than 3x3 3/4 in., but as regards to different formats the porportions wi ll vary. Anyway I took that to mean that for a composing card to be used with a 4x5 neg the opening should be no smaller than that mentioned. But would'nt you want it to be the same dimensions as the format you are using?

Thank you very much for the input, all is appreciated!

Clark King

[Dave Willison]

Clark:

Composing cards are a rough aid that allows you to determine camera position with a given lens and format. When you need to be exact, use the groundglass or one of those expensive monocular viewfinders. The homemade cards that I've used rely on a 4x5 opening, even though 4x5 film is slightly smaller. The opening approximates what the lens sees and is held at a distance of one focal length from the eye. If you have a 150mm (6") lens, for example, hold the card 150mm (6") from yor eye to compose.

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[scott jones]

Hi Clark,

I use a card with a 4x5 hole and attach a string at the bottom with a black mark on it at 150mm for my 150mm lens. I hold this mark to my eye socket and thus know the right distance for the viewing card. More marks can be put on the card and different focal lengths. I use my card constantly...

Scott

[Steve Baggett]

You can make the opening any size that is convenient as long as you (1) make the ratio of the sides 4-to-5 and (2) take into account any reduction (or enlargment) of the dimensions in calibrating the focal length measurement. For example, I use a small plastic card that fits in my shirt pocket with an opening of 2-in by 2.5-in (4 to 5 ratio). Since the opening's linear dimension is 1/2 the format size, when the opening is 45mm from my eye, the focal length view for 4x5 would be twice that, i.e., 90mm. Just mark the card accordingly; in this case the focal length for the view is twice the measured distance from the eye.

[neil poulsen]

I like having mine 4"x5". Since I use it for 4x5, holding it the focal length from my eye gives me about the same framing as as that seen by the film. I also used a coat-hanger to make mine, so that I can easily see outside the field of view.

[Bill Glickman]

B&H sells one ready made for like $15 that has a tape which has fl's for 4x5 on one side and 8x10 on the other.... it works very well and is much cheaper than those expensive viewfinders which are bulky vs. a thin piece of cardboard..