No, I'm not talking about rating HP5+ at 320 instead of 400. That's consistent. You do one set of tests, and then you establish a personal film speed rating for your way of shooting, and then when you set your meter at 320, and take a reading, you know it will in fact record correctly on your film. Digital doesn't work the same way - most if not all digital cameras can't be set slower than ISO 100. Period. And again, if you're aiming for a specific f-stop to control depth-of-field, if your sensor is off, you end up with having to adjust the aperture up or down to compensate, or you spend all day screwing around with your lighting set-up to get the exposure right. If you're constantly moving your lights to adjust the exposure at the subject, what you see on the digital camera LCD will not be what you record on film. Changing the distance from source to subject is always changing the quality of the light as well as the quantity.
Originally Posted by hoffy
I'm NOT bashing digital as a tool - digital cameras can do wonderful things in the studio. I'm just saying don't mistake them as an analog (pun intended) for a film camera. You CAN use a hammer as a screwdriver, but why? You'll still have to get the screwdriver out to finish the job. What digitals do is provide instant feedback. This is their blessing and curse - you can see right away if what you shot is giving the right look to the lighting set-up, to a point. The little LCD on the back of your camera does NOT have the same contrast range as your computer monitor, or your inkjet printer, so what might look like an ok highlight may be blown-out when you view it full-size. I've also seen and heard way too many people say that "I don't need a meter - I can just test it with my digital until I get it where I want it". The speed of feedback gives the false impression of control, and leads to sloppiness.