divinman,
I'm not saying the focusing rod approach is the only way to go, but it works for me. I just love to shoot nudis. They are beautiful, they don't dart off behind a rock, and you can get a decent pic even in really bad conditions because the column of water between the nudi and your lens can be just a few inches. With this rod, I can fill the frame full of nudi and not waste resolution in photoshop later cropping a tiny subject and blowing it up.
If you're interested, I rigged the rod first, and then figured out what manual focus lengths I needed to set in My Mode to match the lengths of the rod extended and retracted.
To find the right manual focus lengths to set, I took a plastic 12" ruler, found a quiet rock pool, and shot two series of photos in manual focus mode, first with the rod extended to the long focal length, and then again with it retracted to the short length. I deliberately set things up to use a low F number so I could tell later on the computer where the depth of field was.
In each case, I put the tip of the rod at the 6" mark as if I was shooting a nudi sitting on the 6" spot, and shot along the length of the ruler. I started with a manual focus length I knew would be way too short, then for each successive shot, I shifted the manual focus up one notch, and wrote down the frame number and the manual focus length for that shot. The idea was to start way too close, and shoot each new shot with the manual focus shifted up one press until the focus was way too long. Somewhere in between would be the focal length matching the length of the rod.
Then, I pulled up each series of photos on the computer. Looking at how badly the gradations each side of the 6" mark were in or out of focus, it was easy to see which frame had the middle of the depth of field right about the 6" mark. The manual focus length for that frame was my magic number which I then used as the focal length for the pre-set My Mode to match the rod length.
Don't do what I did first and take the pics on your lounge room floor, because it doesn't work. Well, it does--on land--but your focus will be way out underwater. Remember from your OW course - things look 1/3 bigger underwater. That's why you have to take the shots and find the right manual focus length in saltwater.
The manual focal lengths I finished up using were 12cm for the long rod and 8cm with it retracted, but that will change if you use a different length rod or put your short electric tape marker somewhere different to where mine is. Also, I have no idea yet what will happen when I lash out one day and buy a dome port.
Anyway, that's what's worked for me, and I just love supermacro now.
Btw, I have noticed that far from scaring little fish, the focusing rod can be helpful. Several times now, I've put the rod onto a rock near a small fish, and guess what? Rather than get spooked, they sometimes turn conveniently side-on to check out what on Earth the tip of the rod represents to them. Lovely.
Finally, to Nay. Buy the strobe. You won't regret it. No more problems with the lens barrel obscuring the bottom left corner of your close up shots. And you can get very close. Much better pics.
