Valuable information here...
I think I will look into more styrofoam tricks after I finally break down and get a flash unit...
I like the idea of velum and I was about to suggest lining it with foil as well...
This is far more sensible than my silly suggestion earlier to get a white pillow case, put a clear plastic bag in it, inflate it, tie with rubber bands...
It's so much more directional and it will cause much less loss of power...
I love it! Thanks jemison!
I-TTL or E-TTL durned well better be through the lens...
The thyristor on the flash is just for when you use it in 'dumb' mode...
When you set a flash exposure (power level) on the flash unit itself in dumb mode, it will send out a set duration of light... This works independent of anything else...
However, sometimes the photographer gets it wrong or the subject is more reflective... A thyristor is used to correct such mistakes.
On my flash, there is a chart listing ISO, distance and aperture.
With a certain ISO at a certain aperture, you should leave the flash at a certain distance to get a nice balanced exposure.
If the subject is really light or really dark or really reflective, things can get a bit out of control for exposure and the only method for the photographer to control flash exposure in this case would be to move the flash unit closer or farther.
The thyristor (the sensor on the flash) will attempt to compensate for these issues and - assuming that you have placed the flash in the correct spot - will adjust the flash exposure according to the light that gets returned to it...
This only applies to dumb mode where the flash is doing the calculations.
Higher end flashes naturally have these features, but do not necessarily use them.
Many settings on the flash are dependent on the distance from the subject. The camera will use the information of focal distance from the lens and use that for a much more accurate distance reading to base the flash exposure calculations on. Then, pre-flashes will help the camera to fine tune the flash duration based on things such as reflectivity. There will be no further need for the thyristor on the flash. The camera uses it's metering ability for the pre-flashes.
I'm 99% sure that this is accurate.
Feel free to correct me if I'm wrong.
Oh and regarding painting it, talk to Bower64... don't forget to use "Canon L Lens Off-White" and a requisite red ring ;).
Message edited by author 2006-08-04 00:27:41. |
