How Critical Is Enlarger Alignment?
I've only owned two enlargers, an Omega B600 and a B22. I aligned both of them w/ small levels, making sure the lens board was the same as the base. Always got sharp prints. I was thinking that since I usually stop down to f5.6 or more, that would probably cover any errors? All I know is DOF w/ a camera lens, and if I were shooting a 50mm or 75mm on a 35mm camera, the same focal length of my 2 enlarging lenses, f8 would cover a multitude of sins. Even considering that an enlarger is blowing up a small negative many, many times, wouldn't the same sort of DOF apply? Not a direct correlation of course, but when in doubt stop it down as long as you don't have real long exposures?
The two most critical planes are the negative stage and the lens. If they are out of alignment, it is very difficult to make prints that are sharp corner to corner.
It is also important to have the lens and the easel aligned, but in the case of alignment failure there, depth of focus can help you a bit.
If the negative stage and the easel are not in alignment with each other, your prints will also be out of square - it is possible to have sharp corners, but skewed shapes.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
Bear in mind that an enlarger is really a macro camera with the negative as the subject and the paper taking the place of the film receiving a larger than life size image.
Originally Posted by momus
The most critical relationship is between the lens and the negative.
"People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.
Taking great care to perfectly align an enlarger is like using a tripod when the conditions allow, instead of hand-holding: the best and easiest way to significantly increase sharpness. I personally try hard to have sharp grain in my prints.
I align my enlarger every 20-30 or so hours of printing or whenever I bump my head into it in the dark.
This subject is quite similar to that of depth of focus, something that can be important when there is doubt the film cannot be held perfectly flat. Assume the tolerance converges to 0 and be happy with prints that are always sharp (from a technical point).
I know Bob Carnie disagrees but actually it's not as critical in terms of sharpness as you might think if a lens is stopped down. I occasionally use tilt of the head and lens board with my enlargers to correct perspective. However with an older 5x4 I used in the past this wasn't possible so you needed to tilt the enlarger easel, even with a 1" or so difference one end to the other on a 16x12" print there was no loss of sharpness stopped down around 3 stops.
What's more critical is parralell alignments to prevent distortion.
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Enlarging lenses are flat field and one is dealing with a minimum depth of focus, not to be confused with depth of field.
There is a reason we focus on grain, if one considered that there is a good deal of tolerance then the need for grain focusers would not be needed
as we could slap a negative in , focus by eye at a distance and close the lens down.
I have never found this to be true, I have my enlargers bolted top and bottom and laser align constantly , I also use glass carrier and Apo lenses slightly longer than normal.
I rarely would dare disagree with Ian Grant who is my chemistry Guru, but in this case I will.
But then as a professional printer and photographer, you have the need and as well as the facilities to be able to do that; I'm wheeling my enlarger in and out of my bathroom to make prints for the hell of it
I one of those types who figure, if you aren't going to do it right, why bother. How important is equal and adequate tire pressure in all four tires? I see folks going down the freeway on three temporary spares and one flat. I call the cars "Bondas" because they're half Honda and
half Bondo. But they seem to get where they want to... ker-lunk, ker-lunk, ker-lunk............ Enlargers are easy to align.
The size of Airy disks and circles of confusion can be optimized for any depth of field required as represented in this slight modification of the view camera focusing equation (equation #38 in http://www.largeformatphotography.in...DoFinDepth.pdf):
N_max ~ 20 / (1 + m) sqrt(dv)
N-max = F number
m = magnification
dv = focusing leeway on the baseboard, represented as the distance on the enlarger column between good focus on the highest and lowest portions of the curved or askew negative. (if 'dv' is zero then your negative is not curved or enlarger/baseboard/easel is not askew)
20 = constant for circle of confusion about 0.15mm on the print
I was in the camp of "why bother" until I tried printing my first 20" x 30" enlargement. After two days of working on getting good exposure, dodging and burning, then processing and split-toning, I got what I thought a perfect looking print. I then spent some money to mount it and hung it on the wall. Only then I noticed that when you get real close, it is obvious that the center is perfectly sharp but the edges are slightly blurry. That same week I bought Versalab Parallel. From that point on, any time I print bigger than 8x10, my first step is to check alignment. No more uneven sharpness for me. When you pay attention, uneven sharpness looks even worse than blurry all-over. Make your own conclusions.