Help understanding using a strobe

[Kingpatzer]

Howdy all,

I've got a new dx-2g and i've been gifted an older sea&sea YS-90DX strobe. I understand how to connect the fiber optic cable to the housing, have a tray and handle and the rest.

What I'm not sure about is what settings to use on the camera so as to avoid over-exposing the picture with the strobe. Can someone walk through the basic idea of what I want to do in order to get a decent exposure with an external fiber-optic strobe?

Thanks!

 

[Puffer Fish]

First off, welcome to the never-ending money pit that is uw photography..

With that setup, you will only be able to shoot manual strobe control, meaning you have to learn the setting that combine ambient light with the strobes light and produce the correct exposure...usually takes some practice.

But first you need to make sure you have the camera and strobe working together...if the camera is using a preflash... you need to have the strobe set on preflash... if not.. well you get the concept.

Practice on land, starting in a somewhat dark room so the flash is the major light producer and take some pictures... and play with the dial on the strobe that adjusts the output.

Also, make sure you are using the lowest ISO...

Then go outside in bright light and see what happens...most likely the 1/60 of a second default strobe speed will let too much light in...so you need to learn how to control the shutter speed..

After you get the hang of making good exposures on land (learning to make the adjustment in less than 4 shoots)... time to go diving...

The strobe now needs to be way off to the side.. you will need to be closer than you think.. and now the adjustment skills come into play..

Rather short version of the overall process.

 

[JohnB47]

Usually, the way that people calculate flash is with a guide number. The strobe manual may tell you one to use as a starting point. You divide that number by the distance to the subject, and the result is the f-stop to use. Of course, your mileage may vary. When you see your results, you fine tune the guide number. And, of course, the guide number will be different for each strobe setting. All photography is an iterative empirical process: you try something, observe and record the results, re-adjust and try again. When you find something that works, keep doing it - but also keep trying new things.

 

[herman]

Realize that even with a nuclear powered strobe you max distance to effectively light an object is around 10 ft, less with the strobes you have, 6 to maybe 8 ft max. If your camera has a histogram function, turn it on and learn to use it. Your cameras display will often lie to you, the histogram will always give you a good indication of the actual exposure of the shot. Learining to use it speeds up the shoot, check, change setting and shoot again process a lot. You also really need to learn to use full manual mode on your camera, auto setting, even those for UW are just not up to the job IMO.

 

[hammerhead man]

Kingpatzer, here is a link to a ys090DX manual that explains how to setup the camera, and how to adjust the light control knob: http://www.seaandsea.com/PDF_manuals/YS90DX.pdf. To identify the f-stop, depress the shutter release button halfway. That will focus the subject and tell you what shutter speed and f-stop you are using. Then set the light control knob to the appropriate setting (as described in the manual) and take your picture. Depending on the visibility conditions, the strobe may need to be adjusted one stop up or down.

Hope this helps.

Regards,

Bill

 

[herman]

Kingpatzer, here is a link to a ys090DX manual that explains how to setup the camera, and how to adjust the light control knob: http://www.seaandsea.com/PDF_manuals/YS90DX.pdf. To identify the f-stop, depress the shutter release button halfway. That will focus the subject and tell you what shutter speed and f-stop you are using. Then set the light control knob to the appropriate setting (as described in the manual) and take your picture. Depending on the visibility conditions, the strobe may need to be adjusted one stop up or down.

Hope this helps.

Regards,

Bill

Unless I misunderstand you, that is going to result in grossly overexposed photos. Without the flash the camera is going to try to come up with a combination of F-stop and speed that will be acceptable with ambient light. When the strobe fires that is going to be way off. The best solution is to shoot manual and do the math yourself then let the histogram tell you how much you are off.

 

[bvanant]

Start at f4.4 (which I think is the smallest aperture) and 1/120 sec. Shoot at strobe half power then adjust strobe up or down from there.
Bill