 BetterPhoto Member |
TTL TTL flash has the flash turn off when the film has enough light. This is right is it not? Then why when I flash a dark wall I seem to be getting the same amount of flash as alight wall. Shouldn't a darker wall need lots more flash and therefore I see an obvious difference in the amount of TTL flash? Thanks David
|
|
|
|
||
|
John A. Lind |
David, A couple of questions: (a) Were you testing the TTL flash control? (b) Assuming the answer to (a) is yes: Was the flash on a camera body? If so, what make/model flash and make/model camera body, and did the camera body have film in it? Some of the following you may already know. I don't know your knowledge level about TTL flash operation. Testing TTL flash control requires it to be mounted or otherwise hooked up to a camera body. It must be "dedicated" for the specific camera body to which it is attached. The camera must be turned on in a mode that allows for TTL flash control, and there must be film in the camera. The reason for all this: By itself (not on a camera body), a flash in "TTL" mode will dump full output when the "test" button is used to trigger it. The camera body isn't there to give it the quench signal. If there's no film in the camera, it will also typically dump full output as there is very little light reflecting off of the pressure plate on the camera back. The "no film in camera" is a common error in testing TTL flash mode, even by those intimately familiar with both the flash and the body being tested. I've done it a few times myself. Also look at the distance you were using to do this and ensure it was within the flash's working range for the film speed you had it set at. A "dark" versus "light" wall may not need that much difference in light output; at least not enough that you can see the difference with your eyes. You will see more difference by changing your distance from a wall (e.g. from 20 feet to 15 feet, to 10 feet, to 5 feet). Even it's easier to measure how long it takes for the flash ready light to come back on at the longer distances (if they're within the flash's working range for the film speed in use). For testing TTL flash and camera body combinations (among other things) I use a "scratch" roll of film. This is a cheap roll of "generic brand" film that will never be processed. When I rewind it, I do so carefully until it just disengages from the take-up spool so that a little leader is still left. This allows using it again. When the leader finally wears out I throw it away and buy another one. The one I'm using now has probably been run through cameras about 20 times. -- John
|
|
|
|
||
|
This old forum is now archived. Use improved Forum here
Report this Thread |
||