Quote Originally Posted by Terry Bowyer View Post
Is anyone out there able to give me an easy to understand explanation of this 'bellows extension compensation' that I have been hearing about. Just bought my first 4x5 camera (Zone VI) with a 210mm and 80mm lens. I haven't taken any photos yet, but like to be prepared for when I do.
Hi Terry,

I'm somewhat new at this too, but the easiest method I've heard described is that every 25% increase in your bellows extension from infinity focus = 50% increase in required exposure.

For example, you have an 8 inch lens (210mm), then your bellows extension for infinity focus is 8 inches. If you're focusing closer, you extend your bellows. So if you extend your bellows to 10 inches, you've increased your bellows extension by 25%. Increase your exposure by 1/2 stop.

This is born out by the more complicated formula (for me to do in my head) of bellows extension squared divided by focal length squared = exposure comensation.

Other methods are given in earlier posts to this thread or at: