Wide Angle Lens (20) on Canon S40 - Need some Help

I have been shooting with my Canon S40, WP 300 case and Sea&Sea DX90 strobe for about 2 years now with some wonderful results. I just purchased a Sea&Sea Motor Marine II Wide Lens (20) and the conversion adapter. I was hoping I could get some tips on how to optimize my results (...and I know there are lots of limitations on this wide angle set up)

The adapter and lense cover the AF sensor so I am using manual mode. The instructions stated to set the focal distance to infinity, which I have done. Flash is set to off. So here are my questions:

1. What mode is best to operate in (P, Av, Tv or M )?

2. The lens offers F stops for given distances, however, I know the digital comera does not align with a film camera's F stops...how do I compensate for this?

3. With the WP housing, I can only change the F stop in the Av mode because of housing limitations. This means I cannot use Tv, P, or M if I intend to adjust the Av settings. Any suggestions on what to do about this?

4. Are there any other suggestions that you may have to accellerate and optimize my results with the Wide Angle Lens?

Thanks everyone.

On 3) Ok P and TV doesent make sense when you want to change the F-Stops.

There is no way to use the M mode with the S40 -> I upgraded to the S50 for this reason, but also the S45 works. You may be able to get it Cheap on Ebay (maybe used)

Simon

Simon, thanks for the response. I am trying to aviod putting much more money into this set up...I am saving for digital video now...so buying another camera unfortunately insn't in the cards. My goal is to optimize what I have. Anyway, any more input on this and other questions would be welcome.

The adapter and lense cover the AF sensor so I am using manual mode. .

Do you really mean the AF Sensor or the AF Assist Beam? I'm not familliar with the S40, but I think if there is enough light the S40 should be able to AF. If there is not enough a dive light will do the trick.

2. The lens offers F stops for given distances, however, I know the digital comera does not align with a film camera's F stops...how do I compensate for this?

These figures on the MMII 20mm lens are simply indicators of the depth of field one should expect with this lens on the MMIIEx, you don't have to bother with them you will have at any stop a depth of field greater that what is indicated.

I don't know how you trigger the YS90DX (optical cable?) but only the M mode should give consistent results or the Av mode with the YS90DX set to PRE to eliminate the preflash and the F stop selected according to the guide number of the YS90DX and subject distance. Any way you've found the right combination since you've been using it for two years. The lens adapter shouldn't change anything. I left mine on my WPDC700 permanently even if I dont use the 20mm or 1:2.