bicycle LED as safelight

On Tue, 24 Feb 2004 11:04:01 -0500, Luigi de Guzman
wrote:

I know that this has been asked here before, but google doesn't supply
a suitable answer. Everybody seemed to want to talk about lowering
the voltages on bulbs, not using LEDs.

There are red led Christmas lights that are very reasonable to
purchase. About $6.00 for a string of 35.

Personally I like the Thomas safelight with the low pressure sodium
bulb.

I use 13 red LEDs (mounted close together) as a safelight.
Did all the standard tests with VC paper and no fogging.
Make sure they are red and not red/orange.

Jorge

Luigi de Guzman wrote in
:

I know that this has been asked here before, but google doesn't supply
a suitable answer. Everybody seemed to want to talk about lowering
the voltages on bulbs, not using LEDs.

I have a pair of red LED bicycle taillights; three red LEDs each, red
lenses, and intend to use them as safelights. I use variable-contrast
papers. These are LEDs, not bulbs, so I figure they're more or less
monochromatic. And I've used VC papers in red-bulbed safelight
darkrooms before.

Will this work?

Seeing as there are commercially-availble LED safelighting solutions,
it would be kind of silly for me to buy them specially, if I have
something suitable already at hand.

-Luigi
www.livejournal.com/users/ouij
Photos, Rants, Raves

Why don't you just test it? Put a coin on some paper, shine the bicycle
light at it for 5 minutes and see if the coin image shows when the paper is
developed. This is not really a question that anyone can answer on a
newsgroup. It is also faster to just test it.

PSsquare
"Luigi de Guzman" wrote in message
...
I know that this has been asked here before, but google doesn't supply
a suitable answer. Everybody seemed to want to talk about lowering
the voltages on bulbs, not using LEDs.

I have a pair of red LED bicycle taillights; three red LEDs each, red
lenses, and intend to use them as safelights. I use variable-contrast
papers. These are LEDs, not bulbs, so I figure they're more or less
monochromatic. And I've used VC papers in red-bulbed safelight
darkrooms before.

Will this work?

Seeing as there are commercially-availble LED safelighting solutions,
it would be kind of silly for me to buy them specially, if I have
something suitable already at hand.

-Luigi
www.livejournal.com/users/ouij
Photos, Rants, Raves

wrote


Personally I like the Thomas safelight with the low pressure sodium
bulb.

They supply a yellow light. Is that safe with VC paper?
Not that that is an issue with me as I use graded paper. Dan

On 25 Feb 2004 14:54:06 -0800, (Dan Quinn) wrote:

wrote


Personally I like the Thomas safelight with the low pressure sodium
bulb.

They supply a yellow light. Is that safe with VC paper?
Not that that is an issue with me as I use graded paper. Dan

By VC paper, you mean variable contrast? I have used Agfa VC paper
with the Thomas with no fogging.
I do intend to test the safelight without the filters, and also with
amberlith as replacement filters.


take the " _ " out of to reply by email

Luigi de Guzman wrote in message news:

These are LEDs, not bulbs, so I figure they're more or less
monochromatic.

They are likely to work, but LEDs are nowhere near monochromatic.

The safelight test using coins should be done on paper that is already
uniformly exposed to give a mid to light grey. What you are looking
for is the absence of a slightly paler grey where the coins were. If
you don't, your test will not be sensitive enough to ensure safety.
Kodak have a pdf file on safelight testing.