# Thread: Bellow extension expsosure help!

1. ## Bellow extension expsosure help!

Hey!

I'm just a little bit confused with bellow extension exposure, I know what it means and stuff but i'm just wondering if it applies to me and my camera, but I still have trouble understanding the ones with mathematical formulas haha!

I use a sinar F2, Will I need to use bellow extension exposure if I have the bellow stretched out completely on the standard Sinar rail? or does it only count when I add a second rail/bellows for like, say, macro stuff?

If It does occur with it extended on the standard rail, can anyone recommend me what they view as the best one to use? I saw the bellow exposure with bacon video and I wasn't sure if that was for me cause I would be doing full body environmental portraits and it would be hard to measure that little paper.

Thanks everyone! I'm still learning

Dave.

2. ## Re: Bellow extension expsosure help!

Divide the extension by the focal length of the lens. Then square it. Can be done mentally. If you want, use the calculator on your cell phone. If your extension is 300mm and you are using a 150mm lens then you have 2^2=4. Quick and simple.

If the object you are photographing is about more than 10 times the size of your film, you don't need to bother with it.

3. ## Re: Bellow extension expsosure help!

Once upon a time I enjoyed math. Now I am perfectly happy to rely on a foolproof calculator from Calumet that allows you to put a small chip in the scene and measure it on a scale at the ground glass. The scale gives you the exposure adjustment and is dead accurate. Truly a no brainer.

If memory serves, there is a downloadable version on this site. You might try searching.

4. ## Re: Bellow extension expsosure help!

I like the analogy of a spraygun. When you pull it back further from the wall, you have to spray longer for the same thickness of paint.

At 1:1, the lens is twice as far from the groundglass as at infinity, so the exposure has to be four times as long.

5. ## Re: Bellow extension expsosure help!

Originally Posted by lenser
Now I am perfectly happy to rely on a foolproof calculator from Calumet that allows you to put a small chip in the scene and measure it on a scale at the ground glass. The scale gives you the exposure adjustment and is dead accurate. Truly a no brainer.
I have often wondered why people prefer this (just to myself, not saying that it won't work for you). Not only can this be tricky or impossible with certain subjects, putting the thing there and then measuring the image on the GG and looking up a table seems very tedious to me. Much more so than a little division and multiplication on a cell phone. It's not like it's really advanced math or a complex formula. But to each his own .

6. ## Re: Bellow extension expsosure help!

...I get out my Horseman film plane exposure meter...

7. ## Re: Bellow extension expsosure help!

but would I need to do this with my normal Sinar F2 bellows on the rail or does it only count when I add a second rail/bellows?

8. ## Re: Bellow extension expsosure help!

Originally Posted by Anupam
I have often wondered why people prefer this (just to myself, not saying that it won't work for you). Not only can this be tricky or impossible with certain subjects, putting the thing there and then measuring the image on the GG and looking up a table seems very tedious to me. Much more so than a little division and multiplication on a cell phone. It's not like it's really advanced math or a complex formula. But to each his own .
I prefer a Quick Stik myself, easier and nothing to have to put in the scene.

10. ## Re: Bellow extension expsosure help!

David,

I use it often on my Cambo SCX with one bellows and any lens that I use for a close up scene. Did a still life yesterday with one bellows and a 210 Caltar that required a 1.5 change in expsure and that was no where near the bellows limit.

Anupam,

While I'm not going to use it with a rattlesnake or other biting critter, I like the extreme ease and accuracy of using the chip and scale method. It doesn't distract me from the subject and lighting like trying to do a detailed calculation does. Like you, that's just my preference and not meant to judge anyone else's method. I just don't want to have to change my thinking from what I'm doing.

I just place it against part of the subject, read the scale on the ground glass, set the fstop according to the scale or otherwise adjust the exposure so I maintain the depth of field I want, take the chip out and shoot.

By the way, the Calumet system gives a direct reading of how much to increase either the f stop or shutter speed. No tables to refer to so it is elegantly simple.

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