baddpix

Hi
I am using a canon eos 350D (rebel XT) with a Canon 100mm macro lens in an Ikelite housing. I am using Ikelite strobes (DS50+DS125) and I have a problem when using the macro lens.
When I am taking picture underwater I sometimes have a problem of the lens stops talking to the housing and the apeture appears as 'OO' in the viewfinder.
Has anyone else has this problem, and if so, is it curable?
Thanks
Dave Chillari

I have had this problem several times and I think I've got it under control.

Apart from dirty contacts, other possible causes are:

• wet contacts, caused by condensation in the housing. To avoid this, do the usual stuff - put some dessicant inside the housing. Assemble the housing in advance of the dive, so that the dessicant has time to work. Don't allow the camera to heat up in the sun. etc
• accidentally depressing the lens release. On the Ikelite SLR housings for Canon 20D and 350D etc, there is a small lever on the left side (below the large knob for the zoom gears) that is used to depress the `depth of field preview' button on the camera. The lever is also designed to be rotated through 180 degrees to engage with the lens release button on the camera body, so that you can change lenses after opening the front lens port. When you assemble the housing, make sure that the lever is not waving around inside the housing near the lens release button! Otherwise when you descend at the start of a dive, the increasing pressure may force the end of the lever to gently depress the lens release button, and hey presto, no communication with the lens. If you get Aperture 00 during a dive, or if the camera ceases to respond to everything except on/off switch, my suggestion is to try gently rotating the lever AWAY from the camera body. It's worked for me several times.

Thanks for all the comments - I seem to have touched a few raw nerves there  B)

One question, do you shoot TTL now?

Yes. I use TTL all the time with my single strobe. It works for me. I agree with dhaas that Canon eTTL2 is an outstanding system. Especially in the rough waters down here, TTL is fantastic for getting a correct flash exposure on a moving target. Ikelite's eTTL2 interface was one of the strong selling points of the Ikelite housing for me (especially the flash exposure compensation controls on the back of the housing).

Yes, I realise that using a manual controller on the second strobe will effectively eliminate the TTL function of that strobe. That's why I asked how important it is, in practice, to have TTL working on the second strobe.

As I understand it, none of the available systems includes a `ratio control' to tell the second strobe to put out (say) 1 stop less light than the primary strobe.  So even if the second strobe is working on eTTL2, I would still have to adjust the lighting ratio manually, by moving the second strobe further away from the subject (as dhaas says) or ?? putting a diffuser on. Is this still much better than just having a manual power control on the second strobe?

I guess it all depends on the type of picture. dmoss seems to be recommending TTL on twin strobes for macro, but manual for wide angle.

Anyway thanks for the multiple votes in favor of the dual sync cord. I think I will go that way (and buy two!)