Wild-goose-chase: 17x20x1 mm glass - Red Safety Filter

zsas · May 7, 2013

Anyone have an idea how I could find the below, but red, photo-paper-safe, has to be glass, heat resistant, 20mm long (long side measured below), 17mm high and 1mm wide, and preferably cheap...thanks in advance

richard ide · May 7, 2013

Hi Andy.
Your request as presented does not give enough information to be specific. I think it would be a good idea to tell us what you are thinking of doing.
Regards
Richard

zsas · May 7, 2013

Yeah figured as much, I wanna put a saftey filter in my dichro enlarger head to be able to toggle with and w/o safety filter. I know I could solve for this in a number of ways (under lens filter, etc)....

But was hoping somone would say...."yeah buy this, and have a glass cutter cut it for $5...."

What is a "this"?

Maybe that?
http://pages.ebay.com/link/?nav=item.view&id=251271524650

zsas · May 8, 2013

I found a picture of what I want, Leitz makes it but it is $100....I want that red glass safety filter pictured below....but done on the cheap, I can't justify spending $100 for a red safety filter:
http://www.bonavolta.ch/hobby/images/photo/v35bw.jpg

C'mon Apug, don't let me down.....you all always have some MacGyver trick up your sleeve. No one knows how to find a thin, photo-paper-safe red safety filter? I can't even figure out if a red 25a is considered "safety"??? I've seen a thread here where somone thinks its photo safe, but really didn't know.....no one knows? Thanks in advance for your ideas

richard ide · May 8, 2013

Not as elegant but a VC filter holder which clamps to the lens would allow you to use it for a red filter.

zsas · May 8, 2013

^ I have that actually, I hate it
http://www.etsy.com/listing/65920161/polycontrast-filter-kit-kodak-in

paul_c5x4 · May 8, 2013

My first choice would be someone like Edmund Optics, but they wouldn't be cheap by a long shot.. A low cost alternative would be a flat sheet of glass from an old Kodak safelight, but... Old glass is notoriously difficult to cut as it gets brittle with age and it may not be "heat resistant" enough.

Neal · May 8, 2013

Dear zsas,

Maybe this will help.

Neal Wydra

zsas · May 8, 2013

Now we're talking! Thanks Neal, so the magic question to you or any curve-wavelength-physics-of-light-and-color-pros, does the Red Dicro filter (item #52-528) block the right wavelengths of light to be color safe?

This is the PDF of the red:
Dead Link Removed

Though not as costly as the $100 Leitz linked above $30ish is plausible but not perfect

zsas · May 8, 2013

paul_c5x4 said:
My first choice would be someone like Edmund Optics, but they wouldn't be cheap by a long shot.. A low cost alternative would be a flat sheet of glass from an old Kodak safelight, but... Old glass is notoriously difficult to cut as it gets brittle with age and it may not be "heat resistant" enough.

Nice ideas! The Kodak safelight option is plausible though that glass is really thick...and fails one of my criteria (1mm thick)

Edmund, yep Neal has some info above...it works but then cost gets a bit much...

This is one of those riddles where you know something shouldn't cost that much to MacGyver but I seem so stumped finding the right material....

Keep the ideas coming...much appreciated

removed account4 · May 8, 2013

hi andy

have you ever seen one of those clamps that are used
to hold gobos infront of lights, or reflective / black/white &c cards
over. below to the side &c of lights ?
they are clamps on both sides and an adjustable snake/arm in between ...
can you just get a safelight filter, from an old bullet or square safelight
and just clamp one side to the filter,and the other to your enlarger body ?
you won't need to cut or trim or anything, ... and it would be adjustable ...
and probably would cost only a few dollars ..

zsas · May 8, 2013

Thanks John. I've the mechanism (below) just (just being the operative word), need some glass as specified in post 1, that I can insert into:

Wanted solution, a red glass as specified in post #1 to replace the yellow you all see in post 1 and in the first pic of this post:

I think I should be able to solve this little riddle with a beat up used 25a and a glass cutter but
I've no idea??

jeffreyg · May 8, 2013

This could possibly work for you. I have made some graduated filters from Cokin or Lee clear (I believe) polycarbonate square filters by dyeing them in RIT fabric dyes. The dye solution was very hot and they did not warp. They can be cut to size but I don't know about the color wave length. The optical properties if that is an issue are very good. But I think they are more than 1mm thick. Also check Anchor Optic division of Edmonds Optics.

http://www.jeffreyglasser.com/

zsas · May 8, 2013

^Dying glass in RIT? That's te kind of MaxGyver I'm talking about! Hummm....maybe take a cheap-old-skylight/uv-filter boil it in red RIT have it cut to my 17x20mm spec???? Hmmm food for thought

Is a skylight filter permeable?

MartinP · May 9, 2013

Cut down a piece of rubylith and sandwich it between two bits of microscope slide, or even just stick it on one piece. The camera filters you mentioned will be even less safe than the 'proper' red filter.

It would actually be simpler just to make an under-lens swing filter using rubylith, a piece of plastic or plywood as a frame and a few cm of alloy strip as a support, attached somewhere convenient near the lens-stage.

MattKing · May 9, 2013

Would a glass slide mount with a piece of rubylith inserted solve your problem?

zsas · May 9, 2013

I worry about staring a fire. I put a meat thermometer into my enlarger head and it got to 200F. A Roscolux #19 can get to 220....I think it has to be glass to make me sleep at night and not catch flame if I ever turn my back????

MartinP · May 9, 2013

The part seen in the photo above, from the OP, is from a Leitz Focomat V35 enlarger isn't it? I'm not going to dismantle mine now to check, but I think I recall that the dichroic filters are after the heat-filter in the light path and not in the hottest part of the head.

However, removing one of the filters being used for the variable-contrast filtration will mean that you need under-lens filters to use VC paper anyway -- so wouldn't that be the easiest place to put the red filter? (Plus you get one in the under-lens set anyway, so don't have to make anything except a simple bracket to support the filter-holder).

zsas · May 9, 2013

Yep it's a V35. I use graded paper and the MG head above actually has one of the two Dicro filters missing (I got it that way). So it is useless even for MG paper and I thought I'd mod it to hold a photo-paper-safe red filter.

I put a thermometer right where the light hits the Dicro head glass filter and it got to 200F. A Roscolux can get to 220F and that's cutting it close for comfort.

Seems the most safe route is the Edmund glass filter cut to size ($40ish) or buy a b/w only head ($100), like this Leitz part:
http://www.bonavolta.ch/hobby/images/photo/v35bw.jpg

Or a under lens filter, which I have but just don't really like the ergonomics:

Really not too much of a bother just want to put that broken part to work...

polyglot · May 10, 2013

MartinP said:
Cut down a piece of rubylith and sandwich it between two bits of microscope slide, or even just stick it on one piece. The camera filters you mentioned will be even less safe than the 'proper' red filter.

It would actually be simpler just to make an under-lens swing filter using rubylith, a piece of plastic or plywood as a frame and a few cm of alloy strip as a support, attached somewhere convenient near the lens-stage.

I was going to suggest this. Or if you have a 6x6 glass slide mount, take the glasses from that.

zsas · May 10, 2013

Think I might have won my own MacGyver challenge.....

$3.42 for a piece of 3x3 piece of glass.....I've a glass cutter, just need to do the darkroom-penny-paper-test:
http://www.dickblick.com/items/34958-2983/

jvo · May 11, 2013

disqualified?

isn't that a bit incestuous - winning your own contest?!?!?

jvo

zsas · May 18, 2013

Ok some updates. Blick didn't sell that red glass at the store but they sold red glass paint made by Pebeo. I bought some thinking after I painted the glass it would be darkroom safe. Well no dice, the red #04 and red#05 failed the penny test, as well as a mixture of reds #04 & #05:

The paint was cheap $6 a bottle so it was worth a try.

I give up....gonna just use my 63mm lens on my enlarger and the under lens holder. Then I will have more room under there....

Thanks all for the brainstorms

polyglot · May 19, 2013

Do another penny test with the hole blocked with cardboard. You might find that light is leaking from elsewhere on your enlarger.

And give some rubylith a go. It costs way less than that paint you just tested.

Doremus Scudder · May 19, 2013

I don't see why a #25 red filter would not work. I've checked the spectral sensitivity of Ilford MG paper (which should be fairly representative of most, if not all, VC papers); it seems to be insensitive to wavelengths above about 550-600 nm (see the Ilford pdf http://www.ilfordphoto.com/Webfiles/2006130200232336.pdf )

A quick check of my B+W filter catalog shows that the 091 filter (#25) cuts pretty sharply and does not transmit anything below 600 nm (the cutoff seems to be at about 625 nm).

Get a good quality #25 red filter and cut it down to size and Bob's your uncle.

Best,

Doremus

Wild-goose-chase: 17x20x1 mm glass - Red Safety Filter

Moderator

Privacy & Transparency

Privacy & Transparency