I have an HMC 40 on loan from my dealer.. Is there a way to change the IRIS and Gain independently . I do not have the manual.

Not really. IRIS, shutter speed, and light stimulate the camera to control the gain. You can set max gain though.

Good luck,
Dan

Yeah, on the 40, gain is controlled through the iris dial. You can limit it to +12db or +24dB in the menu settings (and I highly recommend limiting it to 12; going above 12 can make the image turn to oatmeal). There's even a super-ultra gain setting of +34, but it's incredibly unflattering to your image.