bellows extension factor - getting the hang of it - any suggestions : )!!! ??

[Kevin Crisp]

I'm with Alan. Once I got the quick disc, printed it out and laminated it and put it in the camera bag, I stopped worrying about this.

[Alan Klein]

I'm with Alan. Once I got the quick disc, printed it out and laminated it and put it in the camera bag, I stopped worrying about this.

Just remember to remove it from the camera view after using it.

[Kevin Crisp]

That wouldn't be fun to spot out of the print....

[Doremus Scudder]

The calculations are not difficult. Make a table with exposure factors for each lens you own at different bellows extensions. Then keep that and a small tape measure with you. When working close-up, its as simple as measuring the bellows and consulting the table.

Best,

Doremus

[monochromeFan]

The calculations are not difficult. Make a table with exposure factors for each lens you own at different bellows extensions. Then keep that and a small tape measure with you. When working close-up, its as simple as measuring the bellows and consulting the table.

Best,

Doremus

THis is getting strange... its almost like the tables and scales that are found inside teh Time Life Library Photography book series when dealing with bellows and 35mm macro photography

[Doremus Scudder]

THis is getting strange... its almost like the tables and scales that are found inside the Time Life Library Photography book series when dealing with bellows and 35mm macro photography

It's exactly the same thing. Camera format or lens focal length make no difference to the inverse-square law. Once you extend the bellows away from infinity focus, the intensity of the light starts to weaken at the film plane. At twice the infinity focus, you get just 1/4 the light.

FWIW, I simply made a table that I carry with me that has columns for all my lenses; 75mm, 90mm 135mm 150mm 180mm 200/210mm 240mm and 300mm. That and a tiny tape measure are all I need to deal with bellows extension factors.

Best,

Doremus

[Robert Opheim]

I do the same thing as Doremus! I have calculated distances from the center of lens to film plane and shown that correction on a 3 1/2 x 5" cards that I keep in my camera case. I have a number of different lens lengths - So each lens has a different card. I measure with a very short tape measure the distance and refer to the card for that lens and length for bellows factor. I also look at the film info sheet for reciprocity correction if I am using a long exposure. Added correction for filters used. For black and white I make those corrections on the meter as I decide where to place the shadows and what development for highlights to give each negative. I mark the film holder for that development. For color I don't use a zone system process - so I place the exposure on the meter ring - with the corrections listed above.

[Mark Sawyer]

Okay, here's probably the simplest method for math-o-phobics:

Close down the aperture of your lens to 1 centimeter wide, measured through the front element. Put a little mark on your aperture scale there.

When photographing, just close to 1 centimeter mark and measure your bellows extension in centimeters. That's your actual f/stop. 25 centimeters bellows extension? That's f/25. 36 centimeters bellows extension? That's f/36.

Then you can open or close any number of stops using the positions of the conventional stops on the scale. The only math is reading the measurement of the bellows and counting stops up and down.

[maltfalc]

just convert your bellows extension to f-numbers. if you have a 140mm lens focused at a distance that adds 60mm of bellows extension, giving you an effective focal length of 200mm, that's f/1.4 to f/2.0, one stop darker.

[Kiwi7475]

But here's the real question... if I use a 200 mm lens focused at a bellows extension of 140mm, do I gain 1 stop? ;-) (ignore that whatever I photograph won't be in focus)