Setting up a budget substrobe 200 rig. tips?

[bgi]

Looking for tips for some things I may have missed.

I've never used a detached strobe under water, so if you're inclined, please take a look and see if I'm missing anything.

I'm upgrading the Canon from the old S70 to an S90 this year. I think I got the S70 down pretty well underwater in years past. My best shots with the S70 were macros due to the comparative lack of backscatter and good illumination. I'm expecting a lot more from the S90 and the strobe. The case is a WP-DC35. I was happy with the S70 case, so I'll stick with Canon.

The strobe I've bought is a used Substrobe 200: the reason for this post. It comes with a tray, 4075 arm, diffuser, and a 4100 sensor. I realize the benefit of the manual sensor, but it costs a about half as much as I paid for this whole strobe outfit. I'll be shooting in manual mode with this camera/strobe combo anyway so that doesn't concern me.

I've also ordered the Inon UWL-100 28AD lens and mount for the WP-DC35. Shooting with the S-70 underwater even at 28mm was pretty restrictive. The strobe should be able to illuminate this wide lens pretty well, especially with the diffuser.

Things I'm aware of:

1. To disable the camera's preflash, the camera will be set to manual mode.
2. The camera flash will be ON when I want the strobe to fire. There's no auto-flash setting in manual mode to avoid so this is simple enough.
3. Manual mode will give me an opportunity to think about the shutter speed I'll select to provide a good mix of ambient light and strobe light. I want those upward shots to have a nice blue water background. I'll be able to control that in manual.
4. The camera's thumbwheel is not available underwater, so I'll have to switch to Tv mode to select shutter speed. Speeds selected will stick when I go back to Manual [edit].
5. When using the strobe, I'll attach (with velcro) a home-made reflector of sorts near the flash on the case to direct the flash upward toward the sensor. This will also hopefully prevent the camera's flash from causing backscatter.
6. I'll set the camera flash power on low to save battery and reduce the chance of backscatter from it. If I must, I'll crank it up so the sensor sees it, but I don't think that will be a problem.
7. I'll use the exposure guide on the strobe's battery cover to select power and aperture. Judging distance underwater will be a challenge, but I'll be able to see the results and make adjustments as needed. The S90 has a VERY nice screen and histogram to judge exposure results.
8. With this much power, I should be able to use ISO 100 with the diffuser most of the time (effectively ISO 50 with the diffuser?)
9. I'll manually set the white balance or use the "Flash" white balance preset. I believe I can set a custom white balance underwater with a white object and just go with that unless the flash preset color balance is looking good.
10. I'll shoot RAW+JPEG to provide more options later. Flash memory is so cheap now...
11. There's the obvious O-ring care, charging, etc.

So... what else should I be thinking about to make the best of this combo?

How negatively buoyant will this be? Should I be thinking about zip tieing a floatie to it?

The arm set isn't very fancy or very long. Do you think I'll have backscatter problems with it on distant/wide shots?

thanks in advance

 

[BrettF]

Looks like you have all the bases covered.

One other thing you should consider is that the S90 also offers an ISO 80 setting. This will be helpful if you run into overexposure issues. The SS200 is overkill with a point and shoot camera, but since the S90 offers more manual control than other cameras in its class, you should be OK.

Flash white balance should work fine. Other white balance settings should be OK too, such as sunny day, cloudy day, and the custom white balance preset.

I would highly recommend using the diffuser. When shooting wide angle, the strobe should usually be facing straight ahead to minimize backscatter.

The housing itself is near neutrally buoyant. The system may be 1-2 lbs. negative due to the Substrobe 200.

Regards,