I have been getting a lot of inconsistent, unpredictable densities as I have been trying to calibrate my 4x5 camera. I will describe a problem I saw yesterday with idea that somebody might have a hint as to what might be going on. I am a newbie. I am calibrating camera and film and development time and print for an intro to zone class. The teachers have not been able to figure out what is going with me and my camera.

I am calibrating a 4x5 camera (Linhof Master Technika with Fujinon 5.6/150mm lens) , using HP5+400, HC-110 developer, N+1 (development time for this batch was 11'15"), ISO 125. I shot 6 frames and developed them together using tanks and hangers. I shot a gray card with lens cap on for Zone 0, then exposed for Zone I, Zone II, Zone III, Zone VI (1/15, f/64; 1/15, f/45; 1/15, f/32; 1/15, f/11 respectively.) My densities were an absolute 0.09, and net densities of 0.37, 0.63, 0.81, 0.135, the target net densities are 0.10, 0.30, 0.45, 1.05.

The fifth shot was an indoor still life. I placed my shadow detail in Zone III (125 ISO, 1/15, f/14), my highlight detail (Zone VI) was a measured 3 stops greater than my shadow detail. Zone III area on the negative measured 0.24 and the highlight detail measured 0.94. On close inspection of the negative, it looks like I have good detail where I placed Zone III even though I only have 0.24 net density, not the target 0.45.

I don't think the lens magnification factor is an issue. I shot with the lens about two feet the gray card so that I could only have only the gray card on the negative. My 150mm lens was about 150mm from the film plane. Maybe this is called the bellows extension.

In summary, the problem is the gray card densities are 2 or 3 stops higher than I expect them to be AND they are 2 or 3 stops higher than my still light, even though all negatives used the same studio halogen lights and were developed together in the same batch. Does anyone have an idea what might be going on?