Exposure metering when shooting transparent (colored Perspex) objects?

[eumenius]

Hello friends,

I got a small question - what is your favorite way to meter the exposure for such typical studio objects like glass bottles, Plexiglass tableware and other transparent or semi-transparent stuff in a side lighting or backlighting (when the light shoots through your scene)?

Cheers,
Zhenya

 

[vet173]

incident.

 

[Claire Senft]

I have done very little of this. Using an incident meter point the dome at the backgroung for backlit subjects. Point the dome toward the camera for side lighting.

Hopefully you will hear from somebody that has done much more of this work than have I.

 

[eumenius]

incident.

Incident you say. I can say the same, the question is WHERE and HOW to measure it. Imagine a thick red star, X-mas tree decoration, made from organic glass like Plexiglass. It's lighted with a halogen lamp in tight snoot from backwards, so the lamp is diametrally opposite to the lens. There's an another light source, modelling the ribs on a front surface of the star. What and how should I measure?

 

[vet173]

I would incident the modeling source. You might have to use some type of ND in the halogen if the ratio is too large, or increase modeling lamp to adjust ratio. Can you adjust snout so that light source wont be directly at the camera? Can you have it light from underneath? Do you have a spot meter to measure glass lit by snout that will let you exclude light source from reading reflected? I have a seconic 508. I would incident the modeling light, ( turn off modeling light ) then take reflected spot reading on the illuminated star, then the light source for the star. That way I know what the ratios are and how far out the star light source will be a wash.