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!
Experience talking here and I absolutely agree. I use the Calumet wafer for the same net effect. Clearly there are a lot of mathematicians, engineers, scientists in LF/ULF photography that feel empowered to develop any number of iterations for bellows correction. But any measurement irrespective of how "careful" it is deployed and the computation that follows plays second fiddle to the image on the ground glass. And that is all that matters.
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
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