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4x5 film as neutral-density filter

BetterSense

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Aug 16, 2008
Messages
3,151
Location
North Caroli
Format
35mm
I need to cut down the light on my condenser enlarger. I don't have any neutral-density gels to put in the filter drawer, but I could just fog a sheet of 4x5 film and use that. Can anyone see a problem with doing this? I think the polyester base will be able to withstand the heat ok.
 
You could also put tracing paper or white paper in the filter drawer. This would increase diffusion somewhat, but would be a lot quicker to test. Then again, changing out a 120W bulb for a 75W version is also simple. How much of a reduction in light transmission are you looking for?
 
changing a bulb would be the best bet. But I don't see why your 4x5 sheet wouldn't work. As long as it's over the negative, not under
 
That would be the expensive option... 4x5 film is 20 sq" at $1.40 while the Rosco ND is 480 sq" at $6.50.
One reason to use film is to make a perfect center filter to take into account lens falloff and condenser unevenness.
 
I have some expired film, cheap film, litho film, and xray film. But no rosco gels, cheap though they may be.

I thought about paper, but don't condenser lenses actually project an image of the bulb? Also I would worry about paper yellowing or burning.

I'd like to block 2 to 4 stops of light.
 
In a moment of desperation I tried a layer of paper towel in the filter drawer. It seems to work fine and I haven't noticed the embossed pattern in the pictures, although I have yet to do a rigorous test with a blank sheet of paper. For reference, high-quality paper towels are about 5 stops.
 
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