Lighting With Portable Flash Workshop Q & A
The following is an e-mail that was sent to the the group list of my current Lighting With Portable Flash Workshops.
The questions are in normal type, my answers are in bold.
“Hey all,
As I’m reviewing my flash manual for my Vivitar 285HV, I came up with two questions:
(1) The calculator dial on my 285 will give me the maximum and minimum distance I can be from my subject at a desired focal length
Not focal length, it’s aperture/F-stop
and ISO, but I’m assuming that distance is the camera to subject distance.
Mistaken assumption. It’s light/flash to subject distance.
What if I am bouncing the flash off a 10′ ceiling or maybe it’s a 15′ – 20′ foot ceiling? (a) Do I still measure the camera to subject distance or do I measure the camera to ceiling to subject distance?
It’s NOT camera to subject distance it’s flash/light to subject distance. Replace the word “camera” with the word “flash/light” and your thinking is correct. You would measure light to ceiling to subject distance. However, unless you can accurately estimate light absorption of the material that you are bouncing off of, this is a VERY inaccurate way to calculate your exposure. Here are some more accurate alternatives: If you are working your flash in auto mode, you would check the exposure confirmation on your flash. If you are working in manual mode It’s best to use a flash meter, or check your exposure on your LCD screen.
(b) Will different ceiling height affect my results?
Yup
(2) I read in my manual that my auto thyristor can be taken off and mounted on the camera via a Vivitar SC-3 sensor connecting cord (p. 18) How important is this?
Not very, and I’m not sure if they still make the SC-3 sensor connecting cord. If they did, I’d get it; not because it’s important but because it’s more convenient.
Why would I want to do this?
So you can place the flash sensor/autothyristor on the camera to read your subject. If you are bouncing your flash in a way that would not permit your autothyristor to read your subject then the exposure for your subject will be off. Remind me about this during our next meeting and I’ll demonstrate.“
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This entry was posted on Wednesday, February 18th, 2009 at 2:13 pm. It is filed under Learn Photography and tagged with bounce flash, flash, Flash Photography, vivitar 285.
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