Sea & Sea YS25 Auto Strobe

Does anyone have experience of using this strobe with a Digicam - I bought
one at the Birmingham dive show and am practising with it before I go to
Sharm in the new year. It is connected to an Olympus c-5050z using a fibre
optic cable - the internal flash is blocked off and is just used to trigger
the strobe via tha fibre optic.

The strobe triggers ok giving good exposures at close range, but at anything
further than 1-2m and it does not seem to use enough flash power to
illuminate the subjects I'm taking. The water is fairly clear, and I'm not
talking huge distances either - maybe up to 5m.

The camera is set to Aperture priority, ASA 100 with the flash set for
slave. The strobe is set on power setting 1 (it doesn't trigger when on
setting 2), with the F No set to match whatever the aperture I have set on
the camera - usually around f8, but I open it up for longer range shots - it
doesn't seem to matter though, as I don't get the illumination I'm
expecting. The flash cycle time in this situation is very fast, suggesting
that only a fraction of the power has been used.

Anyone any advice?


Chris Quinn

Chris Quinn" <chris.quinn@nospam.zoom.co.uk> wrote in message
news:brsoc3$ke5$1@sparta.btinternet.com...
> The strobe triggers ok giving good exposures at close range, but at
anything further than 1-2m and it does not seem to >use enough flash power
to illuminate the subjects I'm taking. The water is fairly clear, and I'm
not talking huge distances >either - maybe up to 5m.

Hi Chris
First off I have never used a YS25 Auto but on dry land if the flash is
running at full power then you should be able to divide the guide number by
the distance to get the f stop ( if I remember right it was 13 years ago you
know ) in that case the YS25 Auto has max guide number of 15 (in air)
http://www.camerasunderwater.co.uk/w...ts/ys25dx.html
the Thing about light and distance is if you can get correct exposure at 1m
to get correct exposure at 2m requires 4 times the amout of light this is
due to the good old Inverse-Square-Law. This rule dictates that as the
light-to-subject distance increases, a greater area is illuminated and less
light reaches any given square meter of the scene being photographed. Moving
from 1M to 5M is a huge distance.

> The camera is set to Aperture priority, ASA 100 with the flash set for
slave. The strobe is set on power setting 1 (it >doesn't trigger when on
setting 2), with the F No set to match whatever the aperture I have set on
the camera - usually >around f8, but I open it up for longer range shots -
it doesn't seem to matter though, as I don't get the illumination I'm
>expecting. The flash cycle time in this situation is very fast, suggesting
that only a fraction of the power has been used.
> Anyone any advice?


If the flash is firing on full power then there is not a lot you can do
without more power except open the lens up and slow down the shutter speed
to pull up as much the ambient light as possible but you get less DOF and
still have to ballance the flash with the ambient light. If the flash is
using the f stop to calculate flash output you could try setting the F stop
on the flash to be different to the f stop on the camera this might help
cheat the flash to fire on full power if its not . I find that my Canon S40
is great for CU stuff but any long shots of people are often better with the
flash off.

MarkW

"Chris Quinn" <chris.quinn@nospam.zoom.co.uk> wrote in message
news:brsoc3$ke5$1@sparta.btinternet.com...
> Does anyone have experience of using this strobe with a Digicam - I bought
> one at the Birmingham dive show and am practising with it before I go to
> Sharm in the new year. It is connected to an Olympus c-5050z using a
fibre
> optic cable - the internal flash is blocked off and is just used to
trigger
> the strobe via tha fibre optic.
>
> The strobe triggers ok giving good exposures at close range, but at
anything
> further than 1-2m and it does not seem to use enough flash power to
> illuminate the subjects I'm taking. The water is fairly clear, and I'm
not
> talking huge distances either - maybe up to 5m.
>
> The camera is set to Aperture priority, ASA 100 with the flash set for
> slave. The strobe is set on power setting 1 (it doesn't trigger when on
> setting 2), with the F No set to match whatever the aperture I have set on
> the camera - usually around f8, but I open it up for longer range shots -
it
> doesn't seem to matter though, as I don't get the illumination I'm
> expecting. The flash cycle time in this situation is very fast,
suggesting
> that only a fraction of the power has been used.
>
> Anyone any advice?
>
>
> Chris Quinn

the YS 25 is not a very powerful strobe so you really need to get up close
and personal.... if all you want is to do closeup and macro then it will be
OK.. otherwise you'd have been better of with the YS90DX or YS90 auto
strobe. For a lot more info on uw digital try www.digitaldiver.et, there is
a huge ammount of info here.

If you're shooting on apeture priority the camera will choose a really slow
shutter speed and you will get some pretty blurry shots... the 5050 camera
is great but go for manual....start around F5.6 with a shutter speed of
1/125th. HTH