Using a macro converted spot meter as a densitometer ?

[nick mulder]

Hello,

I've been playing around with new films (for me) and on top of that new developers so I've been paying closer attention to the density ranges I'm getting in my negs (printing in Pt/Pd so contrast is a goal) ...

I dont have a desitometer and have simply been comparing neg densities with stouffer step wedges on a light box, slightly less fully determined results but that usually translates only into 1 or 2 more sheets when it comes time to printing (the subjects of my photography at the moment are very consistent in terms of lighting at the front end) ...

Anyhoo - I realized my light box with only two fluorescent was giving inconsistent results across the glass and I measured this with my spot meter - a whole stop out from the centre to the edges ... This in turn gave me the idea that I could look at my negs with the spot meter, thing is it cant focus this close and readings are all up the wall (it a Sekonic L758 Cine) ...

So, plan is that I try putting some corrective optics on the front of it so in effect it becomes a macro spot meter ...

As a start, what kind of elements would I be looking for ?
The area measured in the circle I'm guessing will remain the same (just to be sure >> yes/no ??)
I would measure in EV, and am only after relative measurements so zeroing it isn't a necessity at this stage, but it might be helpful

Any thoughts ?

Nick

 

[doughowk]

Beyond the Zone System by Phil Davis has a section on converting a spotmeter to densitometer. He mentions that, if can't find a 57mm plano-convex lens, any lens from 45-90mm including a normal lens from 35mm camera should work.

 

[Jim Noel]

The originall method presented by BTZS was to put a +10 close-up lens on the spot meter. The meter was then held by its tripod screw base to a base which had a white card reflector beneath it.the negative was put on a stage very close tot he lens of the meter, the negative below it, and the light bounced off a white card below it. I used one for years and foundit very accurate after I calibrated with a 21 step tablet.

I know this is sketchy, but perhaps it will be of assistance.

 

[nick mulder]

okidoki - cool ...

I'll get searching for the element/lens -

thanks!