hi all
I don't suppose there is an app for bellows extension?
thanks
hi all
I don't suppose there is an app for bellows extension?
thanks
See the Reciprocity Timer app for iPhone.
It combines bellows extension, reciprocity compensation and filter factors for a wide variety of films.
I've used it many times.
I was just curious.. thanks!
The f/stop is just a ratio, focal length (bellows extension) divided by aperture. You're standing there with a ruler or tape measure in your hand anyways, why not just figure out the real f/stop and be done with it?
"I love my Verito lens, but I always have to sharpen everything in Photoshop..."
Take a 10 inch lens for this example. If the bellows is less than 10 inches (from the nodal of the lens to the film) then you do not need to worry about bellows factor, it is factor of 1. Once the bellows is longer then 10 inches, say it's 14 inches, then divide 14 into 10 to get 1.4, square 1.4 to get a factor of 2, double the exposure time. A bellows at twice the length of the lens, 20/10 = 2, square 2, will give a factor of 4. You can also use a metric measurement, it does not mater.
If the bellows is shorter than the focal length of the lens, expose without compensation.
at 125% extension add 1/2 stop to the light meter reading.
at 140% extension add 1 stop
at 175% extension add 2 stops
at 200% extension add 4 stops
Just in case anyone’s curious, there actually is an app for Android (I don’t know if there’s an equivalent iPhone app) called Bellows Factor (www.rdq.cz).
Cheers, Allan
My favorite lens in the field is marked 150mm (or 6 inches). Having worked it out ahead of time, for every inch of bellows extension beyond 6 inches I open up 1/3 stop.
With my 210mm (8.25 inches); for every inch of bellows extension beyond 8 inches, I open up 1/4 stop.
These approximations have been close enough for work outdoors.
I can do this in the late afternoon while standing in wind blown sleet (but I don't like it)
Drew Bedo
www.quietlightphoto.com
http://www.artsyhome.com/author/drew-bedo
There are only three types of mounting flanges; too big, too small and wrong thread!
My favorite app is a tape measure
And it never needs charging
I’m with Peter on this one. I made a simple string with segments that I hang on the rear of the camera. When stretched out to measure the bellows, it tells me how many 1/3 stops that I need to factor in.
Bellows factor becomes an issue at the first black section and then 1/3 more for each additional section. You would have to make one for each lens you have or just use a tape measure and do the math.
Here you can see the lens intersects with the string at about the 3rd segment. So I would add 1 full stop (Three 1/3 clicks)
It even doubles as a solution to them sagging bellows with a well placed clip
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