How flat has to be the paper?

The paper needs to be flat -- otherwise you may not have sharp focus across the entire sheet of paper. Invest in a printing easel -- no extra surfaces (two sided of the glass of the contact printing frame) to have dust on them. Also one can remove the paper without moving the easel, so that your paper will be in the correct place under the enlarger each time. There should be quite a few discussions about easels on this forum.

 

It depends a bit on the type and size of the paper. RC/PE paper stays a bit flatter than FB paper. With an 80mm enlarger lens at f8 you'll have about 1cm depth of field on the paper. But I think that it is better to use an easel to keep the paper almost perfectly flat. It will give you maximum sharpness. A smaller size paper that lays loose on the enlarger table also tends to curl during the exposure which will cause blur.

 

It sounds like two of the sides should be able to be moved to cover the paper -- the other two sides are covered by the non-movable sides.

An example of a two-bladed easel:

http://www.bhphotovideo.com/c/product/43031-REG/Doran_PRAE8_AE_8_8x10_2_Bladed_Enlarging.html

There are 4-bladed easels that all four sides are movable:

http://www.freestylephoto.biz/8501-Beseler-Universal-4-Blade-Enlarging-Easel-11x14

 

Most two blade easels have a way to adjust the borders at the fixed sides. The easel may need to be in the open position to access the adjustments.

 

marciofs,

The fixed sides of your two-bladed easel are likely okay the way they are. As mentioned above, there is usually a thumbscrew in the corner that allows you to set the size of the border. Make sure this is deep enough that the paper slips under the fixed sides.

Believe it or not, the fixed sides, even though they are a little bit higher than the easel surface, will hold the paper more than flat enough for enlarging. Contrary to what many think, if you stop down a couple of stops from wide open on your enlarging lens (usually the best spot anyway), there is more than enough depth of focus at the easel for a bit of paper unevenness.

I often correct for small perspective errors when printing by raising one side of the easel. I've raised the easel 2 cm or more at times and never had problems with depth of focus (I'm making 11x14 inch and 16x20 inch prints from 4x5 inch negatives).

My two bladed easels are the same as yours most likely and do just fine.

Best, und schöne Grüße aus Wien,

Doremus


www.DoremusScudder.com

 

This is something I have been thinking about. The important thing is to have the emulsion of the negative in direct contact with the emulsion of the paper.

I was thinking about having a slightly curved base board (highest in the middle. Place the paper on it followed by the negative then place a heavy frame over it with two rubber strips on the edges which hold the negative down and pull it towards the paper.

In theory, perfect contact with the paper but no glass surfaces to keep clean.

I have not tried this... yet!

EDIT: Looks like I didn't read the first post properly!!

In answer to the OP's question - possibly not as flat as you think. Read Barry Thornton's book The Edge of Darkness.


Steve.