studio strobes

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Jon Pike - 23 Jan 2005 05:36 GMT

I bought today an opus m1002 set. Nice little kit, lots of accessories,
very good price.
Came with two heads, and two pc cables. The idea is you run one head off
yoru camera and the other as a slave (both heads are fully slave-ready).
However, 2 minutes of testing on my d-70 has revealed that when acting as
slaves, the output of the heads is drastically diminished. To the point
that the difference between the on-camera flash alone, and the
oncamera+slave is not noticable.
It's not a matter of the heads just not having enough power, because when
attached via pc cable, I get very different results.

The tests are done with fully manual settings. No change on the camera
between shooting with pc cable or via slave, except that the on-camera
flash is engaged to activate the slave. Shutter and aperture were set
manually, and held consistent between the two tests.

Can anyone suggest what the problem would be?

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zeitgeist - 23 Jan 2005 06:16 GMT

> I bought today an opus m1002 set. Nice little kit, lots of accessories,
> very good price.
[quoted text clipped - 6 lines]
> It's not a matter of the heads just not having enough power, because when
> attached via pc cable, I get very different results.

> The tests are done with fully manual settings. No change on the camera
> between shooting with pc cable or via slave, except that the on-camera
> flash is engaged to activate the slave. Shutter and aperture were set
> manually, and held consistent between the two tests.
>
> Can anyone suggest what the problem would be?

try using a slower shutter speed, the slave might be slow. btw, by on
camera flash, do you mean the little fill flash built in to the camera or
the other flash head near or above the camera?

possibility two, when you have a PC cord plugged in the built in flash might
turn off or automatically go to a fill mode, whereas when you shoot slaved
the camera pumps out a full exposure and your slaves are low powered and
their effect is being washed out.

can you see and/or hear a difference in the flash output when you fire them
off either way? I know when I cut the power back on most of my studio, even
battery flash, I can hear a difference in the loudness of the pop and the
recharge surge, and I can perceive a difference in the brightness of the
flash in the room.

> --
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Jon Pike - 23 Jan 2005 06:31 GMT

>> I bought today an opus m1002 set. Nice little kit, lots of
>> accessories, very good price.
[quoted text clipped - 16 lines]
>
> try using a slower shutter speed, the slave might be slow.

I went down to 1/30, so I'm pretty sure that's not the issue.

> btw, by on
> camera flash, do you mean the little fill flash built in to the camera
> or the other flash head near or above the camera?

both.

> possibility two, when you have a PC cord plugged in the built in flash
> might turn off or automatically go to a fill mode, whereas when you
> shoot slaved the camera pumps out a full exposure and your slaves are
> low powered and their effect is being washed out.

The strobe is -brighter- when used on a pc cable. It's ineffective when
used as a slave.

> can you see and/or hear a difference in the flash output when you fire
> them off either way? I know when I cut the power back on most of my
> studio, even battery flash, I can hear a difference in the loudness of
> the pop and the recharge surge, and I can perceive a difference in the
> brightness of the flash in the room.

yes, it's definately firing with less power as a slave.

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EagleEyePhotography - 23 Jan 2005 08:23 GMT

If you are using the camera built in flash it might be setting off the
studio strobes with a pre-flash it uses to gage the proper flash exposure
levels. If it is doing that would be why your photos look as if your studio
strobes are not working as they have fire on the preflash right before the
real flash goes off so the only illumination would be from the on camera
flash only.

>>> I bought today an opus m1002 set. Nice little kit, lots of
>>> accessories, very good price.
[quoted text clipped - 40 lines]
>
> yes, it's definately firing with less power as a slave.

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Jon Pike - 23 Jan 2005 08:41 GMT

> If you are using the camera built in flash it might be setting off the
> studio strobes with a pre-flash it uses to gage the proper flash
> exposure levels. If it is doing that would be why your photos look as
> if your studio strobes are not working as they have fire on the
> preflash right before the real flash goes off so the only
> illumination would be from the on camera flash only.

no, that's not it
though through some more testing I did manage to figure it out.

Apparently they were firing only to the level of the initial flash. i
didn't think these heads were smart enough to do that, and there was
nothing in the literature to indicate they were.

thanks for all the suggestions though, everyone :)

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Wilt W - 23 Jan 2005 07:04 GMT

When flash units are in slave mode, are they somehow regulated by a
photosensor?...if so the on-camera flash might be fooling them into thinking
that there is enough light from the main flash (on camera), and quenching light
output as a result.

Or, if you are using a flash meter to read the light, the problem might be that
the meter is measuring only a part of the time duration that the slaves are
outputting, giving you an artificially low amount for the measured light. Are
you visually seeing the decreased output or hearing a difference in the 'pop'
of the lights, or measuring with a flash meter?

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Jon Pike - 23 Jan 2005 07:28 GMT

> When flash units are in slave mode, are they somehow regulated by a
> photosensor?...if so the on-camera flash might be fooling them into
> thinking that there is enough light from the main flash (on camera),
> and quenching light output as a result.

as far as i can tell, (and the limited documentation) there's no auto
exposure going on. power output is controlled by a little knob on the back
of the head.
http://members.shaw.ca/anonomoose/opus/

> Or, if you are using a flash meter to read the light,

i'm not.

the problem

> might be that the meter is measuring only a part of the time duration
> that the slaves are outputting, giving you an artificially low amount
> for the measured light. Are you visually seeing the decreased output
> or hearing a difference in the 'pop' of the lights, or measuring with
> a flash meter?

i'm shooting with a digital camera and visually comparing the results

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