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A question on Optical Flash trigger

Posted: Sun Mar 15, 2009 10:18 pm
by sury
I have a old Minolta flash (132X) and bought a $10 optical trigger from Ebay to try.
My set up: HVL-58 on my left in Wireless mode, A700 in wireless mode in the middle, M mode, shutter 160, f16 on a Pentax M42 lens, 132X with optical trigger on to my right.
When I fire A700, I see both the flashes firing, but I see only the effect of HVL-58. I turned off HVL-58 and images are underexposed as if there is no flash EVEN THOUGH 132X has fired. Just to make sure that the
flash output is sufficient, I put A700 on a tripod, pop-up flash down, shutter on 2 sec and remotely triggered camera. As soon as camera fired, I pressed the test button on 132x to fire the flash and the image came perfectly fine. This lead me to one inference: By the time my 132X fired, the shutter is already closed on the camera. Since that problem does not exist with HVL-58, the camera and flash are designed to compensate for the communication lag.

If my inference is correct, if I want to trigger two flashes, I am better off buying another current generation HVL flash in the near future. Is that a valid conclusion?

With best regards,
Sury

Re: A question on Optical Flash trigger

Posted: Sun Mar 15, 2009 10:39 pm
by Dr. Harout
Try with a different (slower) shutter speed, not exceeding 1/60s (I hope).

Re: A question on Optical Flash trigger

Posted: Sun Mar 15, 2009 11:51 pm
by harveyzone
Are you using TTL flash metering or manual? Is there a pre-flash for TTL that is triggering the optical slave before the shutter opens?

Re: A question on Optical Flash trigger

Posted: Mon Mar 16, 2009 12:34 am
by sury
Dr. Harout,
I will try with 1/60s and up to see what is the right speed.

Harveyzone,
The flash was in Manual mode. I tried camera in both fill-flash and wireless mode to trigger the Minolta 132x flash. My camera during all these
experiments was in 1/160, 1/125 range for shutter. When I experimented with my A100, I had problme with Camera flashing to focus on dark subject.

One combination I have not tried is using HVL-58 on my A900 and trigger the 132X.

With best regards,
Sury

Re: A question on Optical Flash trigger

Posted: Mon Mar 16, 2009 2:16 am
by Chris Malcolm
My guess would be that when using the Sony flash in wireless mode that the flash control from camera to flash is triggering the other flash before the shutter opens. If so, you need either an optical trigger which can be taught or programmed to ignore the wireless optical flash control, or use a PC cable, or avoid Sony wireless flash mode.

Re: A question on Optical Flash trigger

Posted: Mon Mar 16, 2009 2:54 am
by sury
Chris,
I have tried the combination of turning off the HVL-58 and use 132X solely. I was still getting underexposed pictures.
I need to experiment with it to see at what shutter speed, the trigger lag is smaller so that I can a flash fired while the shutter is open.

With best regards,
Sury