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gibson1525
11-13-2007, 16:03
on a recent night dive i noticed a remarkable increase in backscatter in shots where i was more than 5' away from the subject. while the closer shots weren't affected, the shots further away were so bad i had to throw almost all of them out. my theory is that since it's dark, the internal camera strobe is able to light up more particles and the camera picks these up in the image. is this correct?

ScubaToys Larry
11-13-2007, 16:55
Bingo... It's a relationship between how bring the subject gets light up vs the particles. Now a particle is small so it won't bounce a lot of light, but hitting a little spot a foot away, the light has to travel 2 feet... one to the subject and one back, while your subject 5 feet away requires 10 foot of light travel - so it is dimmer than the spec.

dbh
11-13-2007, 20:54
First off, even with 2 strobes, 5' is about the max. distance you want to shoot. I would be very surprised if you could light a subject that far away with just an internal flash.

You will almost always get backscatter when using the internal flash. the best way to cut it down (or eliminate it) is by using an external strobe and blocking off your internal flash.

Dave

gibson1525
11-14-2007, 06:31
First off, even with 2 strobes, 5' is about the max. distance you want to shoot. I would be very surprised if you could light a subject that far away with just an internal flash.

You will almost always get backscatter when using the internal flash. the best way to cut it down (or eliminate it) is by using an external strobe and blocking off your internal flash.

Dave




i've got an external strobe, but at night the shots from far away were still cominig out with backscatter. that's wherer the internal camera flash comes in.

dbh
11-14-2007, 19:59
If you have an external strobe, you should tape off the inside of your housing to block the external flash. Just leave enough open for your FO cable. If you are still having alot of backscatter, your strobe is aimed wrong. Try angling it out.

Dave

gibson1525
11-14-2007, 20:10
If you have an external strobe, you should tape off the inside of your housing to block the external flash. Just leave enough open for your FO cable. If you are still having alot of backscatter, your strobe is aimed wrong. Try angling it out.

Dave


i've been putting this off b/c it hasn't affected my daytime pics but you're right, i defnitely need to do it for night dives. any suggestions on how? i've got some sort of velcro setup that came with the strobe but it doesn't fit well on my Sea and sea 8000g housing. i was thinking of cutting out a thin piece of plastic that i could fit onto the front of the housing, maybe try and aviod the mess that comes with using tape.

dbh
11-15-2007, 17:17
I am not familiar w/ your setup. With most compacts, painters tape works (but is not the best looking). Painters tape (usually blue) is not very sticky so it will not leave any residue. Of course it goes inside of the housing :-).

Dave

gibson1525
11-15-2007, 18:22
good idea, thanks, i'll give it a try

bversteegh
11-22-2007, 14:40
You can tape a piece of exposed film across your internal strobe - the FO will pick up the IR light that goes through the film, and still trigger your strobe.

dbh
11-22-2007, 17:57
You can tape a piece of exposed film

What is this film stuff of which you speak :smiley2:

Good to see you Bruce.

Dave