[pure-silver] Re: [pure-silver] Re : [pure-silver] Re: [pure-silver] Re : [pure-silver] Re: =?UTF-8?Q?Light_in_the_Lab
- From: "Tim Daneliuk" <dmarc-noreply@xxxxxxxxxxxxx> ("tundra")
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 7 Oct 2021 13:15:39 -0500
On 10/7/21 11:01 AM, thierry.arnaud@xxxxxxxxxxxx wrote:
Interesting!
Thank you Dana!
But it gives no idea of the maximum quantity of lumens of a light which is
behind my red filter.
It's not that simple. The acceptable amount of light depends upon multiple
factors:
- The intensity of the light source in the relevant parts of the spectrum
- The spectral response of the filter
- The attenuation of the filter
- The distance of the filtered light source to the paper, worst case (shortest
distance)
- The highest sensitivity of paper you plan to use
In theory, you could figure this all out analytically, but why bother?
Build/buy a light source with the ability to replace bulbs and filter.
Take a shot at it and do a coin test.
As an aside, it is almost always preferable to have multiple, lower output
safelights in various parts of the darkroom, than one hanging from the ceiling.
In my case, I use one smaller Kodak "Bullet" light over the sink, and two 8x10
wall mounted ones at the far end of the darkroom. This allows brighter
illumination
far away from the most light sensitive end of things (unexposed paper by the
enlarger
and paper in development) while still illuminating the room nicely. I think I
ended up
using deep red X-Ray filters with a 25W bulb in the bullet and 40W in the 8x10s.
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Tim Daneliuk tundra@xxxxxxxxxxxxxx
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