Quote Originally Posted by padraigm View Post
I have exposed 6 sheets of hp5+ sheet with a stouffer 21 step wedge. Measured EV 4 on the base board. Developed the 1st sheet for 4 minutes(normal 12min published Xtol 1:1). Barely can see anything, got nervous that it is underexposed, so jumped to the development 11min as it is closest to normal fopr a sanity check, and about half are visible. Would I be right is assuming I am at least a stop underexposed and continuing will give me limited information with a densitometer? I figure that you should see most steps at normal.
Pad, we must be living in parallel worlds, as I am working right now on the same BTZS thing. My exposure time at 2EV for HP5 was 0.9 seconds. (This time may have been a mistake by inviting reciprocity effects.) It took several trials to nail this down, but the sheets look good.

What you are looking for is an exposure that leaves 20 and 21 clear. This allows you to measure the effects of extended development on the base+fog, which affects your film speed.

Quote Originally Posted by padraigm View Post
Would I be right is assuming I am at least a stop underexposed and continuing will give me limited information with a densitometer? I figure that you should see most steps at normal.
Yes. Just remember each wedge is a half step, so find the one that has some exposure and count up, but be conservative so you don't over shoot it.

Have you got Plotter yet? There's a demo available. I was a little apprehensive about doing this but I feel now that it will be of great benefit. Incident metering is my preferred way of working, and I shoot a lot of portraits in open shade, so being able to accurately expose these and develop them to the right values should speed things up in the darkroom.