Enlarger alignment question

[hgaude]

I am working with a Beseler 23cII enlarger, in 35mm format. I have experienced a 'slight' softness in one corner of some images. I just printed last night and closely examined the print and the grain is sharp in 3 corners and slightly soft in the fourth. I have not rigorously examined all prints in this way to verify if it is always the same corner - that is my next step.

My alignments, lens, negative holder, base all appear to be parallel side to side and fore and aft. I am using a glassless negative carrier.

My assumption is that the only way to get a soft corner is some kind of negative buckling - or am I missing something with alignment?

Thanks in advance.

 

[wildbill]

take a blank piece of film or glass, put a fine X in each corner, stick that in the enlarger, raise it all the way up, focus. Are all four corners sharp?

 

[hgaude]

take a blank piece of film or glass, put a fine X in each corner, stick that in the enlarger, raise it all the way up, focus. Are all four corners sharp?

Would that tell me something different than looking at the focused grain in a print?

 

[Sirius Glass]

No. If the corners focus at a different height, then the alignment is off.

 

[chip j]

A Bes-Align was made.

 

[Jim Jones]

Check the negative carrier for flatness. If it is perfectly flat, enlarger misalignment is likely the problem. To check alignment, I lightly sand one surface of a strip of film in a random pattern with both coarse and fine sandpaper. It is easier to check alignment with this target than with fine grain film. If the enlarger is misaligned, a band of sharpness should move across the easel as the focus is varied. It's been decades since I've used a Beseler 23C, and I don't remember how alignment is performed. One universal way is to shim corners of the negative carrier with tape.

 

[hgaude]

Check the negative carrier for flatness. If it is perfectly flat, enlarger misalignment is likely the problem. To check alignment, I lightly sand one surface of a strip of film in a random pattern with both coarse and fine sandpaper. It is easier to check alignment with this target than with fine grain film. If the enlarger is misaligned, a band of sharpness should move across the easel as the focus is varied. It's been decades since I've used a Beseler 23C, and I don't remember how alignment is performed. One universal way is to shim corners of the negative carrier with tape.

Jim, I was thinking that very same thing. There is a way to align the negative stage fore and aft but NOT side to side that I've found (If I missed that somewhere I'm all ears!)... I considered some sort of shim myself. It was stumping me about a corner being out - I haven't actually checked the neg carrier for flatness yet...

I'll make a scuffed neg and check for focus and play with shims if it comes to that.

 

[hgaude]

A Bes-Align was made.

Is this what you are referring to?
http://www.bhphotovideo.com/c/product/15669-REG/Delta_13310_Bes_Align_4x4_Adjustable_Lens.html

 

[mdarnton]

Are you sure just ONE corner is out? There's no way for this to happen with misalignment, and I would suspect a lens problem. Try turning the lens board, and see if the mis-focus moves around with the change in lens direction.

I have always aligned enlargers by using a grain focuser in the corners with a normal neg--no scratchy things should be needed. You need to figure out which way to move the lens to bring any location into focus relative to the others, and move the lensboard or film to make that type of movement. If the lens wants to be farther away for one side to focus relative to the other, shim or tilt that side so that the film is farther from the lens there. Once you understand the movements, it's pretty fast.

With the Beselers I've used alignment in one direction was set by a screw post from the housing to the frame down behind the lens area that rocks the head forward and back, and in the other direction by rocking the lens left and right by a tilt set screw directly under the lens. I just used masking tape under the neg carrier, myself, however, on many other enlargers.

 

[ic-racer]

Almost always it is only one corner that is out of focus. Think of a chair with 4 legs of different lengths. It rests on three of them. Or, for the more technically adept; 'three points determine a plane [of focus].'

 

[mklw1954]

For minor misalignments, I check that the lens is parallel to the easel by holding a flat piece of glass against the bottom of the lens with a spirit level on the glass. Then I make any adjustments to the two planes as described in the last paragraph of mdarnton's reply.

Since there's a problem in only one corner, are there any problems with your condenser lenses?

 

[hgaude]

For minor misalignments, I check that the lens is parallel to the easel by holding a flat piece of glass against the bottom of the lens with a spirit level on the glass. Then I make any adjustments to the two planes as described in the last paragraph of mdarnton's reply.

Since there's a problem in only one corner, are there any problems with your condenser lenses?

I have the Dual Dichro head, so its diffusion

 

[Sirius Glass]

Is this what you are referring to?
http://www.bhphotovideo.com/c/product/15669-REG/Delta_13310_Bes_Align_4x4_Adjustable_Lens.html

That is interesting. Thanks.

 

[M Carter]

When I aligned my enlarger, I took a black piece of film and scratched a grid into it. My magnifiers don't do corners very well, the grid was very helpful.

 

[smieglitz]

Since it is only one corner, I would suspect the negative has become crimped or is not being held flat by the negative carrier in one corner for some reason. It is a common occurrence in the community darkroom where I work that a student will catch one part of the negative on top one of four rivets the film is supposed to slide under in the newer style carrier. This can crimp the negative permanently and cause the one-corner focus problem you describe. If it happening to more than one negative image, this is probably not the cause unless you are crimping every negative you try to print. Try a different carrier or mask off a negative between two sheets of flat glass and use that in place of a carrier to test the alignment.

The enlarger can be out of alignment in several ways to cause pairs of corners to be thrown out of focus, but I am unaware of anything else that could cause a single corner to be out. You can correct the front to back tilt for near/far corners, the side to side tilt for the left and right pairs, and a probably a combination of front/rear and side to side if a pair of opposite corners are out. But just one? I suspect something is off with the carrier or how the negative is inserted.

 

[smieglitz]

Before investing in one of those adjustable Beseler 3-point adjustable enlarger lensboards, be sure it will work with your lens. IIRC, they are only good for certain focal lengths. I have used them before (a Zone VI model) to adjust flatness but couldn't get them to adjust enough for some lenses. There are two metals boards with a rubber pad between. The three screws adjust the planar relationships by compressing the pad, but there is a limit to the compression between and the double board is also adding to the overall extension. So, you may not be able to bring the lens close enough to the negative stage since the compression of the enlarger bellows may be preventing it in concert with the extension caused by the dual board. At least that is what I recall from using one many years ago.

 

[smieglitz]

And yet another thought comes to mind (also mentioned by someone earlier). It could be your lens. I much prefer to print with older Nikkor EL f/4 lenses rather than the newer f/2.8 models. They are dimmer but don't distort the sharpness in the corners as much as the faster lenses. One corner might just be worse than the others due to a particular lens fault. Observe the sharpness with grain magnifier. It could also be that the image grain just generally falls apart or smears once the sweet spot aperture of the lens is passed. With most lenses, best performance will be about 2 stops down from maximum aperture (e.g., f/5.6 for an f/2.8 lens, f/8 for an f/4 lens, etc.,). Could also be that a cheaper Beslar vs more expensive and more corrected Nikkor or Schneider, etc., lens is causing the problem. I previously owned a Minolta 50mm enlarging lens that was much sharper than many others I've used. YMMV.

 

[hgaude]

After a little more looking at some past prints... The prints that had the most severe cropping were sharpest edge to edge. To me this means a couple of possibilities; negative flatness - i.e. the more the crop, the less of the 'bow' of the negative causing softness to be printed and misalignment between the negative and the lens (that is the only adjustment I'm still not clear on how to accomplish with this enlarger)

I'm going to put the neg between two small pieces of glass as a test to eliminate that variable since that is an easy variable to test and eliminate....

 

[hgaude]

Also, thanks to everyone for the suggestions on this, the feedback and brainstorming is very appreciated. Not sure when I'll get in the darkroom again, but I'll report results.

 

[weasel]

I used a 23c for decades, and one of my complaints about the enlarger was that it was not set up design wise to align easily. I use an omega d2 now that has everything easliy adjustable, and no need for shims and the like that I had to use with the beselar. You can align an enlarger pretty much balls on with a couple pieces of mirror. If you google it you should be able to find a description much better than I can describe. I also use a glass negative carrier, which while being a cleaning pain, eliminates an unflat negative once and for all. It will take you a bit of futzing to get the enlarger aligned the first time, but unless you bang it around a whole lot should pretty much be a one time deal.While doing the aligning, dont neglect checking to be sure the baseboard is truly flat, as is your easel. I would postualte that the least likely source of a soft corner is the lens; and the best lens in the world won'
t correct an alignment problem.