enlarger light source

[david_flockhart]

The time has come to build a horizontal enlarger for negatives

up to 8X20. I have purchased an old 16X20 process camera and

am looking for guidance on selecting a light source. I'll need to

build the enclosure for the light and get a piece of opal glass for

diffusion. Also, do any of you have suggestions about building

the glass sandwich for the negative holder? I was considering

something along the lines of the type in my Durst 138 but didn't

know if Newton rings would be a problem. Thanks in advance

for your ideas and shared experience.

[david_munson]

In terms of illumination, you should take a look in Ansel Adams'

<i>The Print</u>. On page 28 in particular there is a photograph of

the two different light sources he had for his 8x10 enlarger. One is

a cold light setup, the other looks like a bunch of halogen bulbs on

individual switches. He goes into some detail in the text. Whatever

you decide, good luck and keep us posted on your progress.

[david_munson]

Stupid HTML...

[sandy_sorlien]

For odd size negatives I use two clean pieces of hardware store glass

which I tape around the edges. The tape (3M Photographic) separates

the glass by just enough space so that there is no Newton ring

problem. (Dust, though!) I cut a mask from rubylith to surround the

neg so stray light doesn't come through. I use a cold light head on an

old Elwood 8x10 enlarger, #15 green gel to neutralize it for contrast

filters, it's slow but works pretty well.

[stuart_whatling1]

Let's see if we can lose the italics...</i></i></i>. There - how's

that?

[bruce_wehman]

Dave,

Since your rig is horizontal, weight is not a problem and you can go

really hog-wild with light sources. If you choose flourescent tubes,

use a commercial grade ballast, so that they won't flicker when the

switch goes on.....incandescent bulbs, cooling fans, go for it. You

could even use an array of smaller bulbs, green and blue, on

rheostats and do variable contrast.

[david_flockhart]

Thanks for the ideas. I am thinking that the flourescent idea

would be the easiest and cheapest (not the only consideration

but important). Of the various types of flourescent tubes are

there differences that make one type a better choice? Also, what

is rubylith?

 

<p>

 

David

[sandy_sorlien]

David,

Rubylith is a red acetate-backed film used in graphic design --- you

can cut it easily with an Exacto knife. you could also use amberlith,

which is safelight orange, or really any paper or film that would

block light. Ruby or amber translucent materials let the projected

image show through but would not make an exposure on b&w paper, useful

if you wanted to mask out just one area of an image. I'm just using it

to keep stray light away from the easel so I could use black Delta

plastic just as well.