Negative carriers??

[Calamity Jane]

Since I'm building my own 4x5 enlarger, I've been reading about negative carriers and looking at what's on the market and it has left me with a couple of questions.....

1. For decades I've been using a homemade carrier of two (common) glass sheets (up to 2-1/4 square) and not seen any Newtonian effects yet I see where some people say anti-Newtonian glass is required. What circumstances cause Newtonian rings? It was my understanding that Newtonian rings occur when glass is under stress....

2. I see that there are a lot of "glassless" carriers on the market in recent years. What stops the negative from becoming convex under the warmth of the enlarger lamp?

Thanks for the feedback folks!

BTW, if anybody's interested, you can see the various things I've built over on my Web site http://www.geocities.com/diannebest/ - please excuse the digital photography - I have tried stuffing a negative in my disk drive but it won't read properly ;-)

[Louie Powell]

Cal -

Newton rings occur at the interface between film and glass. Anti-newton glass is very slightly textured to prevent irregular contact between film and glass that resuts in newton rings.

I prefer glassless carriers. Yes, there is a chance that the negative could distort from as a result of heat from the enlarger lamp. Actually, if you have larger condensers, they will block a lot of the heat. But the old trick of simply preheating the negative until it "pops" before making the print will prevent this from being a problem.

[Neal Wydra]

Dear Jane,

Looking at your site I can see that you truly consider '"life" a participant sport.

You may want to try enlarging a piece of blank film to see if the Newton rings show up. I use a glassless carrier for 4x5 but finding a glass carrier with anti-Newton glass in decent shape and in my price range has been difficult. I stop down a bit to try and make up for some of the resulting waviness.

In any case, you could build your enlarger around an existing negative carrier to save a bit of work.

Neal Wydra

[Neal Shields]

I finally broke down and got a used Negaflat off the auction site. I love it. It grabs a 4x5 negative with teeth on the edges and stretches it durm head tight.

It is especially useful for type 55 negatives as they are paper thin.

It does however put teeth marks right at the edge of the long sides of the negative.

[Eric Woodbury]

If you are using a cold light source or other diffusion light source, you can use white plexiglass on top of the negative and clear glass on the bottom of the negative. Since newton rings do not occur on the bottom of the negative (because of the texture of the neg), the bottom glass can be anything. The white plexiglass won't generate newton rings because the angle of illumination for the negative is completely randomized.

Personally, I use glassless negatives up to 5x7 and only use glass with 8x10. Stopping down the lens and depth of focus takes care of focus.

[John D Gerndt]

Calamity,

If you are building the enlarger for pleasure there are no worries and you can just tweek until you have what you desire. I built my own 8x10 enlarger out of a Polaroid MP3 copy stand. MP4's are readily available and can ever so easily be converted into 4x5 enlargers. But back to the point, make sure you can adjust the attitude of the negative carrier to match (parallel) the lens. That is really more of an issue than plain glass or special glass. I use plain glass but *sometimes* need to use milky white plex as a top cover to avoid... "those dirty rings!"

I own a Negaflat carrier which is very cool but I have not had a dust problem so rely on the glass to keep things flat and aligned. With all the fuss that goes into making a good negative, might as well take care with the printing too.

Cheers!