135mm Xenar in Synchro-Compur Over Exposed Polaroids

[spacegoose]

Was playing around outside with a Crown Graphic and Lumedyne 400 single strobe (with reflector only), in the late afternoon, about 8-10 feet from subject.

I was flash metering 100 and 400 Polaroid (Type 54/52), and _really_ was blowing out the highlights for both.

I'm pretty sure the synch was set to X. What would the result have been if on M?

I compensated a half stop, because the shutter speeds available on the Synchro-Compur closest to 125 is 100,

I set the meter to sync at 125 (don't think I could have set it to 100), and the shutter only has 100 (and I didn't think I could guesstimate 125) - (can this shutter sync at any speed)?

For 100 vs 125 I added a half stop to the aperture, e.g. if meter said 125 f/22, I would set it to 100 f/22.5, and if the meter was a little over like 125 f/22.5 I would compensate that as well by closing down another half stop.

Still, my Polas were what looked to be 2 stops overexposed.

Any ideas?

[Dan Fromm]

Was playing around outside with a Crown Graphic and Lumedyne 400 single strobe (with reflector only), in the late afternoon, about 8-10 feet from subject.

I was flash metering 100 and 400 Polaroid (Type 54/52), and _really_ was blowing out the highlights for both.

I'm pretty sure the synch was set to X. What would the result have been if on M?

I compensated a half stop, because the shutter speeds available on the Synchro-Compur closest to 125 is 100,

I set the meter to sync at 125 (don't think I could have set it to 100), and the shutter only has 100 (and I didn't think I could guesstimate 125) - (can this shutter sync at any speed)?

For 100 vs 125 I added a half stop to the aperture, e.g. if meter said 125 f/22, I would set it to 100 f/22.5, and if the meter was a little over like 125 f/22.5 I would compensate that as well by closing down another half stop.

Still, my Polas were what looked to be 2 stops overexposed.

Any ideas?

Um, er, ah, what exposure was indicated for ambient light alone?

ISO 400: by sunny 16 (if it was that bright), f/16 @ 1/400 should be about right, f/32 @ 1/100.

ISO 100: do it yourself

[Mark Sampson]

M-sync has a delay in it to allow time for a flashbulb to ignite. X-sync has no delay. When you shoot electronic flash on 'M' the shutter fires after the flash has gone off, so the flash cannot affect the exposure. Can't help otherwise (too many unknowns), but sync is not your problem.

[Bob Salomon]

You would probably have been fine at 1/125. A properly operating shutter is on speed if it is ±30% of the marked speed. So a good many shutters firing at 1/125 are probably at 1/100 anyway. And your shutter could be anywhere from 1/70 to 1/130 anyway (if it is operating properly) and a shutter as old as a Synchro Compur probably is well overdue for a CLA.

[IanG]

Usual reason for over exposure is failling to stop the lens down :D

Ian

[Dan Fromm]

Bob, Ian, at even odds a dollar says he set exposure for flash alone and was creamed by ambient. Using a slow shutter speed, fastish film (ISO 400? Really!) and flash out-of-doors all too often means overexposure.

[Bob Salomon]

I suspect that his shutter speeds are off due to lack of shutter servicing.

[spacegoose]

Thanks for the replies. I did not meter the ambient light :(

I never do inside, and get nice exposures with strobes then.

I guess there's much more light outside (in the afternoon) to consider.

[John Koehrer]

On "X" your shutter is synched at any speed, compensating exposure wasn't needed in this situation.
If you're attempting to use the flash for fill, meter for the ambient and expose about one stop less. This varies with flash/distance/and personal taste.

[spacegoose]

Thanks for the info. What would the procedure be if, let's say the ambient light meters 30 f/8 and I want to use the flash for fill, maybe with the background underexposed by a stop or two?

[Vaughn]

I believe some Polaroid materials can pick up speed as they age.