All right!!! All Right!! OK!!! I hate glass carriers but I got out one of my old scratched up ones and just to prove you all wrong and... well ok you are all right. It did fix it. Damn. I thought my tape was holding the negative flat. My 6x6 glass carrier bites too much of the image so I guess I will have to find glass replacement for my 4x5 carrier. Now which is worse? Scratches and dust and newton rings or slightly out of focus images?
Excellent insight df!
You are using a Beseler enlarger, so get a Negatrans film holder which I believe has glass on one side and does hold film flatter because three consecutive frames are positioned in the holder rather than one. It has been awhile for me and roll film. For 4x5, the Negaflat carrier works great without glass.
Well the good news is that a couple new pieces of glass are definitely cheaper than a 600 dollar Companon S that I was considering. I don't think I have much problem with 4x5 because the film lays so flat anyway and I do always tape it down. Now that I am going to commit to finding new glass and using the glass carrier I am kind of excited about it and maybe will see a difference in my prints. I went to a photography school that taught printing and we used 4x5 glass carriers for roll film. You can take a processed out completely opaque piece of 4x5 film and cut a hole in the center just larger than the negative size then tape your roll film to it with a small strip of silver tape on one edge. I guess I will go back to that.
With any luck, you shouldn't have dust, scratches, or newton's rings ! The diffusion head covers a multitude of .. well, whatever it is that I do ! You might lay a piece of milk glass or diffusion medium on top of the negative carrier (and remove the diffuser from the bottom of the enlarging head if it cuts out too much light). It will make life a little easier.
"One of the painful things about our time is that those who feel certainty are stupid,
and those with any imagination and understanding are filled with doubt and indecision"
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View camera focusing method for enlarging
You can focus an enlarger exactly like a view camera to obtain optimum depth of field for a curved negative. It is easy if you have markings on your column. Image size changes a little, so it takes some trial and error. Your lensboard position will determine the ultimate projected size of the image and your enlarger head height will determine focus.
Guess at a lensboard positon ('focus knob' setting) and then don't touch it during this process.
Move the column up and down to get the center in focus and note the markings on the column.
Move the column up and down to get the edges in focus and note the markings.
Split the difference between the two and set the enlarger head there.
Then stop down and watch the center or the edge and see if you can get it in reasonable sharpness before diffraction takes over. You can just watch the grain as you stop down or, if you like math, you can use this equation based on modular transfer function:
maximum f number for reasonable sharpness = 20 / (1 + m) sqrt(dv)
dv = focus spread, which is the enlarger head distance in millimeters between the point where the center is in focus and the point where the edges are in focus.
Since using this system of focusing I have found some cases where I can get by without my glass carrier, but sometimes you have to stop down so much that diffraction is an issue.
BTW, you could do the same thing with the 'focus knob' if you had markings or a scale there, but since most enlargers don't have this, the way described works best. Also, the millimeter 'dv' value in the equation assumes 'back standard' focusing on the view camera, which is the same as moving the whole enlarger head to focus.