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just_another_actuary
5-Sep-2013, 09:29
Hi everyone,
I have an elementary question on shift in the view camera. I'm having trouble visualizing shift movements, since I'm yet to get my first camera (saving up to buy one by the end of the year).

Could you please tell me if this is correct:
If I have a 35mm DSLR lens that offers a 10mm shift, given the horizontal length is 36mm - if I shifted fully to the right the center, it would mean about 28% of the light from the left would be cut, and 28% of the light from the right would be added to form the image.

A 4x5 film has a length of about 120mm. Would I be right in saying the equivalent of a 10mm shift on a DSLR lens is about 33mm on a view camera? In other words, would I be right in assuming a lens with an image circle of 210mm for 4x5 offers the same amount of maximum shift at infinity focus as a 10mm shift - dslr lens of equivalent focal length?

Thanks!

Sevo
5-Sep-2013, 09:51
In terms of relative distance by film/sensor size, yes. That is, the equivalent of 10mm shift on a 35mm lens for 24x36mm would be roughly 33mm on a 120mm lens for 4x5". But parallel shifts are just one of many possible movements. And absolute coverage is of little interest unless you also consider angular coverage.

Brian Ellis
5-Sep-2013, 14:58
Yes, you're correct. 10mm of shift using 33mm film would be about 27% of the film in the long dimension. To get 27% of 4x5 film in the long dimension would require 33.75mm of shift. The focal length of the lens you're using and where you're focused has nothing to do with it. 10mm of shift is 10mm of shift regardless of the lens or the focus.

I'm not sure what you mean when you talk about a percentage of the light being added and cut. It isn't the light that's changed with shift, it's what's included and excluded in your photograph of the scene in front of you.

just_another_actuary
5-Sep-2013, 18:02
Thanks Sevo and Brian!

Brian, I meant the light that forms the image. Something like this : http://www.dspguide.com/graphics/F_23_2.gif