# Bellows extension

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• 01-08-2012, 10:52 AM
Bruce Osgood
John, I agree.

I made the all to common mistake of answering the wrong question.

I was addressing filter factors and not bellows extension.
• 01-08-2012, 11:43 AM
RalphLambrecht
Quote:

Originally Posted by Terry Bowyer
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.

try thisand start on pge 192!
• 01-08-2012, 12:56 PM
artonpaper
My method is to measure the bellows extension, from the ground glass to the lens board, which, believe me is close enough, then divide that number by the focal length of the lens, square that number, which yields your Bellows Extension Factor, BEF, then divide your ISO by your BEF and set that into the meter and take your reading. Being super precise is not usually necessary, although when shooting chromes it can't hurt.

Example: 11 inch bellows extension, 8 inch lens, = 1.375 X 1.375 = 1.89. ISO 100 divided by 1.89 = 52.9, for a working exposure index (EI) of 50, which in this case will yield a one stop correction. All of this will keep you in a 1/3 f-stop tolerance, an industry standard.
• 01-08-2012, 01:29 PM
artonpaper
PS - Here's a handout that I give to my large format students.

http://dl.dropbox.com/u/16205118/Vie...0procedure.doc
• 09-01-2012, 04:42 PM
I know this has been well and thoroughly covered but perhaps the way I prefer to do it will be of use to somebody. I don't really care for doing math in the field. I want everything prepared for me. I just sit down at my computer and fogure out the bellows extensions for a given focal length that will evenly correspond to stop corrections in 1/3 stop increments going out as far as the bellows on my camera will allow. I then make a small table with P-Touch tape and stick it to the lensboard for that lens. That ensures that I can simply set up the photograph I want and then choose the closest stop correction from the table.

Here's how the tables look, this one is for a 90mm:

90mm

+1/3 - 106mm (4 3/16")

+2/3 - 121mm (4 3/4")

+1 - 127mm (5")

+1 1/3 - 142mm (5 9/16")

+1 2/3 - 156mm (6 1/8")

+2 - 180mm (7 1/16")

+2 1/3 - 202mm (7 15/16")

+2 2/3 - 226mm (8 7/8")

+3 - 255mm (10")

+3 1/3 - 285mm (11 1/4")

+3 2/3 - 321mm (12 5/8")

+4 - 360mm (14 3/16")

+4 1/3 - 404mm (15 15/16")

+4 2/3 - 454mm (17 7/8")
• 09-26-2013, 12:56 PM
Larry L
I use Kodak photoguides for all my lens extension calculations since they have a dial system in the back of the books that will provide the exposure correction by you indicating what focal length of lens is being used along with how much extension you are experiencing. No math (calculator, etc.) is required. Both the Kodak Pocket Photoguide and the Kodak Professional Photoguide have this. The latter also has an extensive section on view camera perspective and depth-of-field controls as well as guides on camera movements. These can be found on E-Bay for reasonable prices as I'm sure they're out of print.
• 09-26-2013, 01:46 PM
pbromaghin
The Cambo Legend conveniently has a scale printed on the rail that indicates the distance between front and rear standards.
• 09-26-2013, 08:11 PM
DanG
Quote:

Originally Posted by Terry Bowyer
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.

To keep it really simple: for B&W film especially, the exposure compensation that works well in the field is: add 1/3 of a stop for every inch of bellows extension over the focal length of the lens that you are using. EG.: with a 6" lens (150 mm) on the camera and with a bellows extension of 9" (film plane to nodal point of the lens) the exposure compensation would be plus 1 stop. I have used this "rule of thumb" for 49 years and it has served me well.
(PS: I don't like thin negs. in BW. If in doubt give a little extra exposure: develop according to the scene brightness ratio.

I use a Zone VI, 4x5 with 75, 150 and 240 Nikkor lenses. I also use a 6x7 roll film back which is especially good with the 75 mm Nikkor.

Enjoy, don't over think it, keep it simple. Shoot film, print lots!

Dan Gordon
• 09-27-2013, 03:26 PM
RalphLambrecht
the easiest way to deal with this is to place a target discinto the subject and measure it with a special disc ruler on the view screen. the ruler will tell you how the exposure has tobe xhanged to compensate for the bellows extenson. send a private email to rlambrec@ymail.com and I'll send you a free pdf of the whole thing
• 09-28-2013, 12:51 AM
pbromaghin
I forgot that the Mamiya tlr's have a bar that comes down into the focus screen that tells you the exposure correction as you focus on close objects.
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