lenses finder film size conversion table...

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photovdz

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even if most of us use 24x36 only, i would love to find a conversion table where it would be possible to compare lenses focal length for various film sizes. It would be usefull when you use old cameras with dim or faded finders for instance.
Of course the table must take into account the image ratio to give an accurate comparaison.
The main 3 images ratios are : square, 4:3, 2:3, but some 1:2 or more exist

Usually the diagonal of the film size is considered "natural" focal length (43mm for 24x36) but we are all used to see 50mm instead.

Does an calculation chart or excel file exist somewhere ? my mathematical abilities are limited but all suggestion would be useful

Stephan
 
yes it is... even if it could be improved by using a ratio variation.... I'll work on it, but I don't have the maths with me ;-)

Thanks a lot...

Stephan
 
It is really simple. Diameter A per diameter B equals focal length A per focal length B, this is the formula to use. A and B are two different formats.
Diameter can be the diagonal of the frame, but it can be width or height of the frame if you prefer that.
Example: the equation 36mm per 85mm (i.e. 135 format frame width per 6x9 format frame width) equals x per 90mm gives you the "corresponding" 135-format focal length of a 6x9 90mm lens to give the same horizontal field of view.
 
Does this help?

Does this help?

It's a chart that matches some popular focal lengths in the 35mm world with lenses available for 6x6 cameras. It takes into account three aspect ratios that you can get by cropping either a 35mm negative or a 6x6 negative: 1:1, 1:1.25, 1:1.5.

I've got a much higher quality rendition of the chart as a PDF file; this jpeg is a very low resolution version. If the chart is helpful, PM me, and I'll email you a copy of the PDF version.

AngleOfView.jpg
 
The above table has an important attribute. It shows a measure of the film gate rather than the usual 6x9, 6 x 6, and 6 x 4.5 ratio.

6x9 which isn't shown can get squirrelly. For example some 6x9 cameras capture less width than 54 x 82, which gets closer to a 6x8.
 
Solinar said:
The above table has an important attribute. It shows a measure of the film gate rather than the usual 6x9, 6 x 6, and 6 x 4.5 ratio.

6x9 which isn't shown can get squirrelly. For example some 6x9 cameras capture less width than 54 x 82, which gets closer to a 6x8.
Click to expand...

I built the chart for myself when I was pondering a Hasselblad purchase, and wanted a simple way to compare focal lengths with 35mm cameras. It wouldn't be hard to expand the chart to include 6x7 and 6x9 formats.

But I'm unfamiliar with the precise film gate size of popular 6x7 and 6x9 systems. Give me some standard target sizes, and I can make the chart bigger.
 
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