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12/14/2007 10:12:58 AM · #1 |
What would a Friday be without a dumb question from me?
I've been playing with two Sigma 500 flashes, using them off-camera with eBay wireless triggers. I've figured out that I can control the brightness of the flazh using an on-flash menu and cycling through ratios in doubling increments from 1/1, 1/2, 1/4, and so on.
Near the above choices is another set of choices to cycle through, such as F 1.0, and so on.
Anybody know what the F nubmers control? I've set it to various numbers and done test flashes, but all I see now are spots. Is it some sort of diaphragm, like in a lens, to make a beam of flash norrower or wider?
I've just been leaving it on 1.
Here's a test shot on the wife last night, with one flash in front, camera-left through an umbrella; and another flash set to lower power behind and camera-right, using a box as a gobo, pointing at her hair.
The colour's a bit off, but I think the lighting worked out on this one pretty well.
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12/14/2007 11:28:39 AM · #2 |
I think it's just another way to control the power output. The F 1.0 signifies f/1.0 for your aperture. Might be a way to compensate for light loss through a narrow aperture? Not sure but that's what I always thought it was on mine.
Edit to add: I'll check when I get back from class...
Message edited by author 2007-12-14 11:35:11.
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12/14/2007 11:52:21 AM · #3 |
Ok I got it, I was right.
Originally posted by Sigma Manual:
You can set the film speed or aperture value on the flash unit manually, if desired.
a. For the film speed â€Â¦ Press the MODE to select the ISO, then press the SEL button to make the
indicator blink. Press the + button or – button and set the desired film speed, then press the SEL
button once again.
b. For the aperture value â€Â¦ When the flash unit is set to the Slave mode, press the SEL button to make
the indicator for the aperture value blink, and press the + button or – button to set the desired aperture
value. Then press the SEL button. |
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12/15/2007 08:19:23 AM · #4 |
Thanks!
I don't really understand it, though. Curses on my low I.Q.!
:-)
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12/15/2007 09:06:36 AM · #5 |
| All this electronic stuff is confusing. I still have an old metz handle flash. It works with dials. The F number would have a corresponding distance with it. I would focus on a subject check the distance on the lens barrel then match it on the flash, the f number corresponding to the distance on the flash is where I would set the f number on the camera. All of this is dependent on the iso that the flash is set at. It's very simple in practice, only complicated in words. |
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12/15/2007 09:26:33 AM · #6 |
Those f numbers control the flashes auto exposure. This is a non-TTL way to get correct exposure and works quite well with off camera flash.
The flash uses a sensor on-board to determine when a set amount of light has hit the subject and then shuts off the flash. If you set the camera ISO and aperture to those numbers set on the flash, exposure will be correct even though you don't have TTL through the wireless links.
Its for this reason that I use cheaper Sunpak Auto flashes for my wireless setup. Since the TTL doesn't work through wireless, having the Auto flashes (with their thyristor sensors saves money while having nice functionality.
It's easy to do, you set the ISO on both the flash and camera to match. You then set the aperture setting on the flash to an approximate range from subject. You then set the camera aperture to match. Ofcourse you have to make sure the front of the flash and camera are pointed at the same subject. Easy, but when in doubt RTFM.
Message edited by author 2007-12-15 09:33:04.
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12/15/2007 09:39:48 AM · #7 |
Oh, I see, thanks!
But I suppose this is all thrown out the window if I'm flashing through an umbrella, and/or bouncing off an umbrella or wall or something??? Or have a lightsphere or omnibounce mounted on the flash?
Right now I'm guessing, chimping, and adjusting. Which has worked well so far. But I'm always looking for a better (easier & faster) way.
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12/15/2007 09:45:58 AM · #8 |
Originally posted by Strikeslip:
But I suppose this is all thrown out the window if I'm flashing through an umbrella, and/or bouncing off an umbrella or wall or something??? Or have a lightsphere or omnibounce mounted on the flash?
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Not necessarily.. as long as the front of the flash (the body, not the head) can "see" the subject, it can get proper exposure. Shooting through an umbrella is out, but bouncing is fine, as long as you are using the swivel head for what it was designed to do, instead of turning the entire flash away from the subject.
The omnibounce or lightsphere will work well to in this mode.
Message edited by author 2007-12-15 09:46:31.
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