Magnifications

Hello and greetings to you all.

I have a question... (obviously!)

If I have a lens (lets say a 150mm lens) on a 4x5 camera and I take a head-and-shoulders portrait. The subject is say 1m from the camera.

OK. I put these figures into the Bob Atkins DOF calculator ... and I get a certain 'magnification'.

If I want exactly the same image but on 5x7 film on a 210mm lens what will be the 'magnification' ? ... and the same again for a 300mm lens on an 8x10 camera...

I'm certain someone knows this ...

Do I get his magnification figure off the DOF calc and multiply the 4x5 figure by 7/5 for the 5x7 and 10/5 for the 8x10 ?

Cheers.

You can't really get "exactly the same picture" since the formats have different ratios.

I think you are actually talking about 'angle of view'. Use this for calculating what you know for the 4x5 with the 150 and then calculate the lens+format for the others and compare the view for the horizontal and vertical angles.

http://www.mat.uc.pt/~rps/photos/angles.html

Oh all right then ...

Instead of 'exactly' insert the word pretty 'much the same' ... :-)

Thanks Darr. I think it might be. I'm trying to understand the DOF for the same image on various formats.

Cheers,