How do I mask glass neg holder?

[gedra]

I would like to begin using my a glass negative holder on my Omega 4x5 enlarger. I print mostly 120 film and some 35mm. What is the best way to achieve exact centering and masking to avoid light scattering? Is it feasible to use one holder for all formats, or should I get a holder for each film size?
Thanks very much.

 

[largeformat pat]

The best way to mask your neg or tranny is to use 3M 235 tape. This tape is like black masking tape. It will not let light through. I would recommend buying the correct holder for each format though. Flea bay has them appear quite often. the link below is to a crowd in Canada who seem to specialize in Omega. Their website has a lot of information.
Pat
http://www.khbphotografix.com/omega/

 

[JBrunner]

My Chromega has enough room in the negative stage to accommodate a piece of mat board cut to the appropriate mask. Works well and is easy to adjust, if your enlarge has similar space. Because I can move the mask without bothering the negative, centering is easy, because I adjust the mask to match the position of the negative, and as such the neg only needs be mostly centered. Saves a lot of 1/2mm head banging.

 

[Robert Brummitt]

I would use spent 4x5 film or un-exposed 4x5.
I then place the piece of film I'm working with and trace around it. Get out my exacto knife and cut out the traceline. I then placed the film inside the hole and silver tape in place.
I did this for my negs and trans. What great is that I can make contact negs or soft focus masks.

 

[Ponysoldier]

You also have the option of using the Omega Masking Device which is inserted below the negative carrier... but, in my experience, the best option is to cut 4x5 film with the appropriate-sized openings. This should allow you to use your glass carrier to full advantage.

 

[Bob Carnie]

Here is how I get exact centering and also mask

In my darkroom I use a different glass carrier for each film format.

1.Set up your enlarger as if you are going to print an image.
2. Set the blades of the easal to print size you reguire
3. take out the glass carrier and rack down the bellows so you see the circle of light .
4. Center your easal with all four edges of the blades touching the light or centered .
5. Now put your negative into the carrier, and move the negative until it is centered in the easal. Once you are centered tape the negative and check again.
6. Now take out the glass carrier with the negative taped in place and flip over the whole carrier and with black electrical tape mask out the negative to the rebate.


If you follow this with each format all your glass carriers will be masked and the negative will be in the proper position.
Each time you print you just need to position the easel by racking the bellows down with no neg in place.


this will put the bulb*lightsource* condensor, negative and easal in perfect alignment using the sweet spot of all combined.

I find it very important to do this for sharp edge to edge , and non flared prints.

 

[gedra]

Thank you all for the tips. I look forward to getting started tomorrow.

 

[Ronald Moravec]

A piece of cardstock, and mm ruler. measure the neg, use two corner to corner lines to find the center and center the cut out where they cross.

Tape the cardstock so it is light tight. MMM black waterproof tape is fine. Put the mask on botton glass on outside.

If your carriers are like mine, Omega should have used 4 pins instead of two so they nicely puch holes on film strips. I can rotate the carrier and place the film on a diagonal. This means you need to make a diagonal mask which becomes advanced geometry. I forget how I did it.

In the end, I filed out the top only of a glassless carrier to accept AN slide mounting glass for 35mm. This is very tricky and requires careful work so you co not go oversize andyou need to keep it centered. Mine works better than the cut down 4x5.

I vaguely recall Omega made a 35mm glass carrier 50 years back, but I have never seen one except new at that time. I would not waste time trying to locate one.

 

[JBrunner]

I vaguely recall Omega made a 35mm glass carrier 50 years back, but I have never seen one except new at that time. I would not waste time trying to locate one.

One of those things you will never find, until you switch to a different enlarger. One month later you will find three, like new, at a garage sale, for 2 bucks.