Photronix Delta III (Model 73) densitometer manual and/or help

Borrowed a Photronix model 73 densitometer, which, as I understand it, is also known as Delta III.

Anybody has the user manual they can PDF me ?

I only have a typed page which pretty cryptic instructions. Amongst them, this sentence: "When measuring thick films such as sheet film or the Kodak step tablet, zero the meter with an edge under the sensor head, but not in the light path."

I do not know what this means. What is an "edge"? And how can it be under the sensor head but not in the light path? Important to me, as I'm not using the Kodak step tablet but the Stouffer TP 4x5 - 21 step wedge, and am trying to measure T-Max 100 in 4x5 format.

Thanks in advance.

My guess is that thick film will increase the nominal distance between the light source and the sensor. You would zero it out by putting the edge of the film between the measuring probe and the platten, to achieve the appropriate gap without blocking the light.

Since your exposure of the film is a bit seat-o-the-pants, I wouldn't worry about it. The relative density measurements won't change, even if the absolute measurement is slightly out.

As others have stated, your method will only give you useful information about relative contrast, but won't be accurate in determining film speed.

Sharktooth said:

You would zero it out by putting the edge of the film between the measuring probe and the platten, to achieve the appropriate gap without blocking the light.

Click to expand...

I'll try this. Thanks.