Calibrating film processing by measuring print density

[bda]

I have got hold a densitometer that measures the reflectance of prints

and would like to use it to calibrate the dvt of my B&W negs. The

process I have in mind is the following:

 

1. Take pictures of a middle gray area/card in full daylight. Use the

camera meter and expose in 1-fstop steps from -4 to +4. Add one

unexposed shot.

 

2. Develop as usual

 

3. Expose each frame on grade 2 1/2. Exposure time is just what is

required to produce maximum black when exposing the base of the film.

 

Now the question is : what values should I read for each zone

considering that maximum black reads 1.9 and pure white is 0 ?

Any other suggestion ?

 

Thanks for a tip from an expert.

Regards

Bertrand

[lindsay_carter]

Okay so I'm no expert, but I am a student. We just did this in class. We photographed a white wall 3 times (after calibrating our light meters). So we did one where the wall was just middle gray, then we opened up 3 f-stops from the original reading, then stopped down by 4 stops (from the original reading as well). Then we used a "normal" film developing process.

 

Next, we read a piece of the clear film (film base+fog) and got a number. Then we read the 3 from the white wall...

 

the Zone I density should be .10 more than the clear reading. That is to determine if the film speed is correct.

 

the Zone VIII density should be 1.10 higher than the clear reading. That is to determine if you are using the correct developing time.

 

He never really did explain why we had to do the middle gray shot, because we didn't use it to determine anything.

 

I hope this helped a little bit and wasn't just a useless ramble. Honestly I'm not the best with photo terms yet, so I only understood a little bit of what you said up there. eh oh well.