I was just sitting here at 5am on a Sunday morning thinking about an easy way to calculate bellows extension factors and thought of something.
Maybe it has been done before or maybe it hasn't.
I have seen some inexpensive small spring-loaded tape measures for sale in fabric stores, craft stores, etc. Unlike hardware store tape measures these can be only 4 or 5 feet long.
OK, so what if I bought a tape measure for each of my lenses where I would need to know bellows extension? Let's say for example, my 300mm f/5.6 Rodenstock Sironar-N that I use for portraits. I would certainly be extending that lens out in order to photograph someone 8 or so feet away therefore I would need to know the bellows factor.
It would seem to me to be very handy if I could simply place the hook of the tape measure on the film plane then pull it toward the lens. Then if I had already marked the bellows factor on the tape using a black Sharpie pen, I could adjust the shutter speed to make up for light loss.
A second idea which is far lighter weight and cheaper would be to use some cloth gift wrap ribbon then note the shutter speed changes needed on it. I could glue a loop on one end that would attach to the back of my Cambo then when I had roughed in the portrait, I could lift the ribbon up to the front standard and quickly know the light loss.
How fine should I make the correction marks? One second increments, half second, etc.?
Does this make any sense to those assembled here today?
Thanks,
Terry
Golly, I've got to get some sleep, I need to be at church at 7:45 to warm up for choir.
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