Bellows extension and exposure

[Ariston]

What is the best app for quickly determining how much more exposure you need for extended bellows? Or is there an easy "rule of thumb" I can use?

 

[Raghu Kuvempunagar]

http://www.kennethleegallery.com/html/tech/bellows.php

 

[MattKing]

If you use just a couple of different lenses, a custom tape measure made up from a piece of ribbon marked with a felt pen is perfect.

 

[Rudolf Karachun]

The best app is your phone calculator,

 

[Doremus Scudder]

I'm old-school. I made a table with bellows extension factors for the lenses I use. I carry a small tape measure. No batteries required.

Doremus

 

[Ariston]

Perfect solution. Thank you all for sharing your experience. Still learning...

 

[Peter Schrager]

not again...no one uses the search feature
if you have a 10 inch lens and you extend it to 12 inches that's one stop..go from there and a tape measure; it won't break like your app and you'll actually know something instead of relying on a machine

 

[Bob S]

If you are at infinity, no correction needed.
½ lifesize open up 1 stop
Lifesize open 2 stops
Twice lifesize open 4 stops.

they are simple ratios, no calculator needed, just a ruler to measure scale.

 

[Mainecoonmaniac]

An easy way is to use a bellows target and ruler. You put the target in your shot then use a ruler to measure your magnification. Way Beyond Monochrome is a great book too. You can download the ruler and target here. The rule is a 100% magnification is 2 stops compensation.
https://www.waybeyondmonochrome.com/WBM/Library_files/TemplatesEd2.pdf

 

[Ariston]

not again...no one uses the search feature
if you have a 10 inch lens and you extend it to 12 inches that's one stop..go from there and a tape measure; it won't break like your app and you'll actually know something instead of relying on a machine

Isn't a camera a machine?

I'm just teasing with you. Thanks for the help!

 

[removed account4]

Hey Ariston
Mateo explains a really easy way to do it in this thread
https://www.photrio.com/forum/threads/bellows-extension.43275/page-2#post-619798
have fun !
John

 

[Ariston]

Thanks John, so it looks like for every time you add 50% beyond the lens' focal length, you add one stop. Easy peasy.

 

[MattKing]

Thanks John, so it looks like for every time you add 50% beyond the lens' focal length, you add one stop. Easy peasy.

Actually, not 50%.
Change extension from 5.6 to 8 - increase exposure by one stop.
Change extension from 5.6 to 11 - increase exposure by two stops.
Change extension from 5.6 to 16 - increase exposure by three stops.
Change extension from 5.6 to 22 - increase exposure by four stops.
5.6 - 8 - 11 - 16 - 22.
Recognize the progression?

 

[Ariston]

Yes, I recognized the progression. I was going by Mateo's second example from 210 to 320 to 450, where he said it was close enough, especially for negative film. If you add 50% to 5.6, you get 8.4, which is close enough to 8 for my unskilled exposure and developing, and is an easier "rule of thumb" for me for negative film.

I've seen your work, Matt, and I know you are an expert technician with exposure, because the tones in your images are beautiful and impressive. If I use slide film, I will use the formula Raghu linked to above, or will eventually have a homemade tape measure ready, as suggested.

 

[MattKing]

If you add 50% to 5.6, you get 8.4, which is close enough to 8 for my unskilled exposure and developing, and is an easier "rule of thumb" for me for negative film.

I smiled when I saw this, because I've been working so long with the 4 - 5.6 - 8 - 11 - 16 - 22 - 32 - 45 - 64 progression - both in and outside the darkroom - that it comes as easy to me as 50%.
In case you haven't noticed, each number is 1.41 (square root of two) times the next one, and each number is two times/ 1/2 the number that is two steps over.

 

[removed account4]

im glad it makes sense to you and matt
I never do macro work or things the require extension
but I never forgot Mateo's post...

 

[M.A.Longmore]

.
And, The QuickDisc . . .

https://www.salzgeber.at/disc/

 

[Mainecoonmaniac]

.
And, The QuickDisc . . .

https://www.salzgeber.at/disc/

Yep. You could measure your bellows extension. I use this method because I'm terrible at math. An arithmetic error can screw up your exposure withe bellows extension.

 

[Ariston]

I smiled when I saw this, because I've been working so long with the 4 - 5.6 - 8 - 11 - 16 - 22 - 32 - 45 - 64 progression - both in and outside the darkroom - that it comes as easy to me as 50%.
In case you haven't noticed, each number is 1.41 (square root of two) times the next one, and each number is two times/ 1/2 the number that is two steps over.

I'm pretty good with remembering the basic apertures, but I remember that the shutter speeds were causing me confusion in another thread because of their seeming doubling. I kept avoiding the math, but now that you point out that it is the square root of two it all makes sense. I'm still learning from you, Matt!

I never said I was a quick learner!

 

[jeffreyg]

I did the math once for each of my three lenses and marked a small retractable ruler tape with three different color permanent markers. It is attached to my lightmeter strap. Just measure the lensboard to the film plane and check the color against the lens that matches. Fast and simple with nothing to remember except that the film holder is loaded and the dark slide is correct.

http://www.jeffreyglasser.com/

http://www.sculptureandphotography.com/

 

[Ari]

Use a marker to draw a rough ruler on the white side of your dark cloth.
That way it's always with you, and you don't have to carry another tool.