Dark on bottom half of shots...

I am sure this is something simple, but a brief search yielded nothing, and I'd like to dive again in the morning, thought I'd see what you guys suggest.

I recently bought a lightly used Canon 20D in a subal housing. Took it out for some dives yesterday afternoon - it is set up now with a 50 mm port and dual DS125's, the camera currently has an EF 50 mm macro lens on it. The strobes are triggered with the appropriate non-TTL sync cord. Furthermore, when the camera is housed, and I'm looking through the viewfinder, everything looks fine. However, once I press down the shutter, the shot shows up in the LCD with the bottom half essentially black.

Outside of the housing, the camera works perfectly.

I deleted all the UW shots I took yesterday, but I took 2 of my Fisheye manual to show you what's going on.

Speak slowly - I am obviously clueless. Apologies for a question that likely has a very simple answer - and thanks a bunch in advance.

Did you exceed the flash sync speed for the camera whilst using flash?

Ie over 1/250th of a second?

EDIT: Or is it 1/200th for those funny Canon thingies.

I was definitely using a faster shutter speed than 1/250. And the fact that I have no idea what you're talking about indicates that this may be what I did wrong. Must find manual...

AAAHHH!!! That's it, just took a gorgeous picture of my Fisheye manual. Thanks so much (for the answer and for being nice about it...)

My guess would be shutter speed as well ... fastest shutter speed is 1/250s on the 20D i believe.

If it isn't that then you have something getting in the way like a big piece of paper or a Sewer Rat .. or maybe a Swarm of Locusts .... all of which i think you would have noticed !

what is the exif info on the shots (shutter speed used) .. does the problem only happen when using the flash ?

the opanda exif reader.tells both were shot at 1/640.

1/250 is indeed the maximum synch. On my Ikelite housing the camera automatically drops to that speed when the strobes are connected, even wehen I have manually selected a shorter speed.. I have some older land flashes that are manual only. With these I have the same: in manual the camera doesnt sense the flash, and you can select all speeds.

It turns out, you can cheat it a bit over the 1/250 the manual says (see attachments), but this only works for non TTL flashes..

1/250

1/320

1/400

(I skipped attaching the 1/500)

1/640

Gerard

I don't think a camera in a housing recognises when strobes are attached .. so underwater at least with most cameras and housings and strobes I have seen you have to make sure your SS is not above 1/250 manully.

If you are using the Canon Flash on land .. then that is a different matter as it limits your shutter speed for you then.