D200 Flash settings with DS-120's

Thanks guys for your input on white balance and TTL setup using the D200 in an Ike housing.

Now, while installing the D200 in the housing and getting it all set up, I looked under the Brackeing/Flash menu. I set the Flash Sync speed to 1/80 and the Flash Shutter Speed to 1/80. Should I shoot at 1/60 or 1/125?

To what do I set the Built-In Flash to? Under manuall I have choices from Full POwer to 1/128th power. I also have the TTL selection.

Do I need to tape the built-in flash down?

Should the modeling flash be on?

What about auto-bracketing? Should I use it and if so, what value?

This will be the first time I've shot RAW. I have a 4Gb card which will give me 150 shots per dive in RAW+ jpeg. Lot's of hard drive space taken up but I'll burn to CD's while on the trip.

I'll be shooting the Nikon 10.5, the 12-24, and the 105. Don't feel it necessary to take the 17-55...Do y'all?

Thanks again to all! This is a great board!

G'day mate,

I have only used the D200 with manual flash underwater and TTL topsdie, but my guess would be that Ike's iTTL system requires the camera to think that it is driving a TTL system (even if you set the housing to manual). For that reason, I would set the camera to iTTL (not manual). You do not need to tape the built in flash down.

You should test these setting topside and make sure it works ok.

Hi again,

I'm not quite sure why you plan to set the flash sync speed to 1/80, but I guess it might not be a bad place to start depending on what you are trying to acheive...At the risk of sounding didactic, I'll have a go at explaining what I mean.

Remember there are two things that influence exposure in a photo underwater. One is the light coming from ambient sources. You modify the amount of ambient light reaching the sensor by changing the camera's shutter speed and aperture. The other source is the light coming from the strobe which is only governed by strobe output and camera aperture. Provided you are shooting in the range at which the camera can synchronise with the strobe, the camera shutter speed has no influence on flash exposure at all. Only aperture changes the amount of strobe light reaching the sensor.

To say it another way, the shutter speed that you set with the camera does not change exposure from the flash at all. What it does change is background exposure.

This is a little confusing because you can actually set a ceiling on the maximum shutter speed you allow the camera try to synchronise with the strobe. This is called the max sync speed. The D200 cannot synchronise with a strobe at a shutter speed faster than 1/250. It can synchronise at any speed slower than this, even when you set the sync speed at 1/250 - provided you shoot in manual exposure mode. To make it more confusing, you can still use iTTL flash in manual exposure mode because iTTL is only controlling the strobe output - not the background exposure.

By selecting 1/80 you are effectively setting an artificially low ceiling on this strobe synchronisation speed. This is useful if you are trying to allow a little ambient or background light into the exposure. If you are tryin to get a black background I would go for something closer to 1/250. As I mentioned earlier. My preference would be to set the sync speed at 1/250 and simply control background exposure by using manual exposure mode and choosing whatever shutter speed (of either 1/250 or slower) you think works.

Finally, as for autobracketing - it can be useful, but I find using manual exposure and adjusting on the fly is more useful.

If you are worried about space, you could think about not shooting the jpegs at the same time as raw. That way you'll get 240 shots on a 4GB card. You can always create the jpegs later. You'll sure be burning a lot of cd's. Have you thought about DVD's or an external hard-drive/portable storage device for backup?

Have a great trip.

Hope this helps...

Anthony,

YOU have been most helpful.

The learning curve of the D200 is very steep but add in UW RAW shooting and it's a prodigious amount of information.

Based on your input, I will change my Flash sync speed to 1/250th.

Thanks for your assist.

Any more detailed input is greatly appreciated.

Dive cheerfully! Ron

Ron,

You won't be needing the built in flash and it doesn't need to be tapped down.

The flash synch speed is important in bright shallow water with bright sand, you might need to bump it up to more than 1/80th under those conditions but it shouldn't matter most of the time. As Anthony said, the back ground exposure will be modified by the synch speed setting. You could also try varying it undere certain circumstances to get different effects, blue v. black backgrounds for some variation.

I would also tend to have two flash cards, just in case one gets damaged somehow (like dropped into a pool of sea water while trying to get it to your computer for downloading). A 2G one can be had for about $80. I've taken to backing stuff up to a separate hard-drive (some just use their iPod). CDs are light and cheap but limited to ~750M, so maybe use DVDs.

I think auto-bracketing is not that useful UW, but that's just my opinion. Better to use exposure compensation when necessary. It uses fewer resources, strobe charge, battery, card space etc.

Have fun.