Need help with FTS using cannon 100 mm macro IS

[dancewithethan]

It seems that I have the most difficulty getting my camera to focus on the full tank.

I'm using the new cannon 100 mm macro IS lens on a cannon 40D body. My concern is the DOF is very shallow that only part of the tank is in focus. Am I using the this lens for the wrong application or my camera setting is not correct?

Please help with the camera and lens setting

Thanks

[swjim]

If you want more depth of field you'll need to either use a smaller aperture (higher f/stop number) and/or back up further from the tank. For full tank shots using a wider lens would probably be a better option (if you have one) as it will give you more DOF at the same distance.

This will help: http://www.dofmaster.com/dofjs.html

[qfrisco]

Is it your 510 liter (120g) tank you're talking about for the FTS? I shoot Nikon and use a 105mm macro, but this should apply to your Canon body and lens as well. My experience with using my 105mm macro is that you have to be pretty far back (15-20 feet) in order to get the whole tank in the frame. Is this your experience as well?

This is why I don't like using my 105mm macro for FTS. It will work, but I don't think it's ideal as I'd rather be closer to the tank and magnify less than be further out and magnify more. Instead, I use a 35mm prime lens, or even my 18-55mm kit lens for FTS shots.

Regarding DOF, I'm not sure how deep (front to back) your tank is, but using your 100mm at about 15ft away (in order to get the whole tank in the frame) from your tank should give you about a foot of DOF at f/4.5 (not nearly enough to get everything in focus). Shrinking your aperture down to f/16 will give you about 4 feet of DOF.

Do you have another lens you can use?