Help! Inconsistant lighting with strobes.

[indiamb]

Hi everyone! I have been using an older photogenic lighting kit (8050 MA) with a flashmaster power unit. I have been taking very nice portraits with it for about 2 months. Recently however, I have been getting horrible results. If my camera is set on the same setting for let's say 10 shots, 3 shots are blown out, 5 of them are very dark with a blue cast and 2 appear to be correct. I am using a 420 EX on a Rebel XT to trigger the strobes. I have determined through test shots using only the camera and the 420EX that it is not the flash or camera (exposures were consistant)but the strobes. I am not sure what the problem is Please Help! I have a couple of shoots coming up soon!:confused:

[elr]

I had the same problem before, I think it's caused by the pre-flash feature of the digital camera.... my old slave strobe fires pre-maturely when I use the 420 to trigger it. It cannot distinguish the pre-flash from the exposure flash. But when change my old slave flash with a digital barebulb strobe, the problem disappears. :D

[elr]

There is a thread discussing a solution to this prob.

http://photography-on-the.net/forum/showthread.php?t=72777

[MCTAV]

I have just got a set of Interfit flash units, one works fine but the other gives very inconsistent results. Every couple of shots it dumps out full power, I just had a word with the technician at Interfits distributors in the UK and he said it sounds like a Thyristor problem and to return the unit for a replacement.

It sounds like your units could be at fault, do the photogenic heads give a consistent output when fired manually at your flashmeter? Thats how I diagnosed the problem with my units.

[PhotosGuy]

do the photogenic heads give a consistent output when fired manually at your flashmeter? That question is important! If you are on a controlled situation, there is no way that I would shoot in any "auto" mode. Put the cam & flash on manual, find the right exposure, & use it! ;-)

[scottbergerphoto]

The 420EX has no Manual Mode. It only works in ETTL. So what is happening is that the preflash is setting off the monolights and the output of the monolights is messing with the output of the 420EX which is the only flash illuminating the subject when the shutter is open. To avoid this, hit FEL, let the preflash fire and set off the monolights, let the monolights recycle and then hit the shutter button. The flash will fire and so will the monolights at the same time. The 420EX is not designed to be a master.

[wwinn]

Hello;

You should invest in a wireless flash trigger for your hotshoe like this one:

http://sell-it-on-the-net.com/online_store/wireless_flash_trigger.htm

[PhotosGuy]

The 420EX has no Manual Mode I can't imagine why they would do that! I thought every flash had a manual mode. Learn something every day, I guess. ;-)

[lostdoggy]

Maybe a little 3M corrossion might help!!!

[Curtis N]

Isn't there a way to tape over one of the contacts on the hot shoe to prevent the E-TTL preflash?

[scottbergerphoto]

Isn't there a way to tape over one of the contacts on the hot shoe to prevent the E-TTL preflash?
Even if you could do that, the 420EX would fire on maximum every time. Do you really want so much light coming from right over the camera?

[Curtis N]

Even if you could do that, the 420EX would fire on maximum every time. Do you really want so much light coming from right over the camera?Depends on the situation, I suppose. Its effect could be mitigated by tilting and swiveling, if the main objective is to fire optical slaves.

I agree it has limited applications and would require considerable experimentation to product the desired effect.