Heiland LED coldlight and contact exposing film for BTZS densitometry testing

[mpålsson]

Dear Members,

I’m curious whether anyone who owns a Heiland LED coldlight has experience contact exposing film with a step wedge for BTZS densitometry testing. If so, I’d be most appreciative to hear how you did it, what settings you used, etc.

[esearing]

This works for any light source. Unfocus the light source, measure light at baseboard with incident meter which gives you mid gray zone V, Then add 5 stops for the time. Or if your enlarger lens has 5 click stops built in, stop it down to f32 , find the time with your meter and set timer, then open up lens to f4. Beware of reciprocity so try to keep it at 1sec or faster.


Its usually easier to do this in camera pointed at a large white sheet of paper on a sunny day, then use your shutter on the lens.

[mpålsson]

This works for any light source. Unfocus the light source, measure light at baseboard with incident meter which gives you mid gray zone V, Then add 5 stops for the time. Or if your enlarger lens has 5 click stops built in, stop it down to f32 , find the time with your meter and set timer, then open up lens to f4. Beware of reciprocity so try to keep it at 1sec or faster.


Its usually easier to do this in camera pointed at a large white sheet of paper on a sunny day, then use your shutter on the lens.

Thank you. Please forgive me if this is a stupid question, but I’m a bit confused by one point. If my incident meter gives me a reading of, say, EV 4.2 and 1s at f/4 (or some other equivalent combination), then what aperture value should be used on the meter to determine the exposure time?

[esearing]

Sorry, my memory failed me from the last time I tried this. I used a spot meter value of a bright white mat then opened 5 stops from f32-f4.
If using an incident meter with a dome then you just use what it tells you since that is the average light for mid gray. Raise/lower your enlarger as needed to get the speed/aperture desired.

Your enlarger lens should have engraved f-stops and can be fairly close to the negative if needed. Raise/lower your head until the light reads something usable. Timers below 1 second may not be consistent, so you can mount a shuttered lens there too, or just go with 1second at a reasonable fstop.

IN camera is easier if you have a 4x5 step wedge. You can even be lazy and use sunny 16 rule on a bright day. f16 and 1/box speed, though in practice you will likely end up at 1/2 or 2/3 box speed depending on your developer.

[mpålsson]

Sorry, my memory failed me from the last time I tried this. I used a spot meter value of a bright white mat then opened 5 stops from f32-f4.
If using an incident meter with a dome then you just use what it tells you since that is the average light for mid gray. Raise/lower your enlarger as needed to get the speed/aperture desired.

Your enlarger lens should have engraved f-stops and can be fairly close to the negative if needed. Raise/lower your head until the light reads something usable. Timers below 1 second may not be consistent, so you can mount a shuttered lens there too, or just go with 1second at a reasonable fstop.

IN camera is easier if you have a 4x5 step wedge. You can even be lazy and use sunny 16 rule on a bright day. f16 and 1/box speed, though in practice you will likely end up at 1/2 or 2/3 box speed depending on your developer.

Thank you again for your reply!

I’m still a bit confused on one point, but I think I didn’t express myself clearly before.

A spot or incident meter is designed to measure the EV value of a scene before the light passes through a camera’s optical system (taking lens + negative). So, the EV value is displayed along with an equivalent combination of shutter speed and aperture value.

But if one measures the illumination produced by an enlarger on its baseboard, there is no subsequent optical system through which the light passes before exposing the negative on the baseboard. Although the meter can give an EV value for this scenario, it is confusing to me what f-stop should be chosen in order to determine the correct shutter speed.

Maybe I’ve misunderstood something?

In his book, Phil Davis recommends setting up the enlarger so that the light on the baseboard measures EV4 at ISO 100 with the enlarging lens stopped down to f/11, then exposing each negative (sandwiched with the step wedge in a contact proofer on the baseboard) for 0.4s to avoid reciprocity. The minimum exposure time my Heiland Splitgrade controller is capable of is 0.5s, so I reduced the light on the baseboard to EV3.66 to compensate. I’ve tried this a few times, but something seems wrong. When I plotted the resulting curves, the toe was very short, which suggested to me the light was too strong. I tried using less illumination, around EV 2.66. But this time the toe seemed very exaggerated, so I still wasn’t convinced the results were useful for analysis. Anyway, this is how I came to ask about this issue.

[esearing]

A light meter measures light - it does the same thing whether pointed outside on a sunny day or early morning light or at artificial light. Your enlarger has variables especially accuracy of time for short exposures. A shutter is more suited for this task.

Do yourself a favor. Go shoot in the real world and take 5-6 shots of the same image of your typical scene or one that has lots of contrast between shadows and highlights. Take good notes about EVs and points on the scene and plot them.
Develop your first sheet, measure/plot it, and scan/print it. Make adjustments to your development if too flat or too contrasty for the grade you want to print normally.
Continue to adjust time/temp/agitation/dilution until you get the negative that prints the way you want it to. Working with the same scene helps you see the changes.
The key to all this testing is consistency and the discovering the flaws/features in your methods and products used. Even after you work it all out for a time, your chemistry will fail, vendor will change ingredients, film/paper sensitivity will change with age, etc.

I burned a lot of film trying to work with HC110 but just never found the right look. Once I standardized my film to FP4+ and Pyrocat as my developer, I found my work method very quickly and learned how my film reacts when I change any variable. Sometimes I take two shots of a scene just so I can experiment with changing my process in order to see the result. No plotting diagrams needed.