image circle

[Daniele Minetto]

What is the image circle to cover 8 x 20"?

[Richard Ide]

Hi Daniele

You need an image circle of 550mm absolute minimum which gives no movements at all.

Richard

[GPS]

The "absolute" minimum is closer to 547 mm maybe even less as the 8x20 format is probably not exactly 8x20. The old Pythagoras again??

[Capocheny]

Well, while we're at it... what about for:

4x5,

5x7,

and 8x10? :)

Thanks in advance.

Cheers

[Oren Grad]

Henry -

Here are the numbers presented by Schneider in their literature:

4"x5": 153.7mm</br>
5"x7": 208.7mm</br>
8"x10": 312.5mm

In practice there are slight variations depending on the exact design of the film holder.

Cheers...

[Capocheny]

Greetings Oren,

Thanks for the info... :)

Cheers

[Matt_6555]

What about 11x14

[GPS]

Exactly the same as 14 x 11

[Oren Grad]

I think 11x14 is somewhere around 435mm. I'll try to remember to measure one of my negatives next time I'm down in the darkroom...

[robc]

figures quoted for 4x5 are usually infinity focus at f22. Smaller apertures usually give bigger useable image circle and focussing closer also gives greater image circle.

Formula for diagonal of film area is √(width^2 + height^2)