Utterly Confounding Alignment Problem

[sepiareverb]

I've exhausted my ideas, hoping someone has some more intelligent insights for me.

LPL 4500, VC enlarger.

I have a sharp image 7/8 of the way across the frame (side to side) then a dramatic out of focus end of the image. This happens across lenses.

1) I tweaked the lens alignment with the adjustment screws- it reads level with my laser unit.

2) I've shimmed the easel, doesn't fix it.

3) I've shimmed the negative stage with tape or card, doesn't fix it.

4) Tried using glass and glassless neg carriers- no difference.

I've printed with this machine for five years with zero alignment troubles. It hasn't moved, been dropped, or whacked. I usually spend a few months printing 810 size proofs, then a month or so printing 1114 and 1620 final prints. This started suddenly with one negative about two months ago, after I'd printed about 15 negs to 1620 over a two weeks. I called Omega and KHB, was given the alignment procedures by KHB which fixed it for a few negatives at 1620. Went back to 810's and all seemed ok. Tried to return to 1620's today and cannot get anything sharp all the way across.

Any suggestions??

I guess I'm going out to shoot today instead.

[Gem Singer]

I assume that you are printing 4X5 negatives.

Have you checked the VC light box to make certain that something has not moved and is partially blocking the light path. Perhaps a VC filter or heat absorbing glass?

[sepiareverb]

No, these are 35mm negs- but I shall check the box.

[sepiareverb]

Box appears fine.

[Gem Singer]

Glass, or glassless negative holder?

[sepiareverb]

Both.

I even swapped the masking stage out for the regular one- no change.

[wfwhitaker]

If your system works OK for 8x10 enlargements, but not for 16x20's, it might suggest a problem with lens coverage. Has your lens been dropped or whacked or damaged in any way?

Does the problem only occur with 35mm negatives? Have you tried changing formats to see if the problem continues?

[Salty]

With my LPL 4500, the only way to print 35mm negatives is to invert the lensboard before putting in the enlarger lens.

[sepiareverb]

Thanks for the input. Multiple lenses show this, and XPAN negs show this too. Yes, the 50's, 63 and 80mm lenses are all on reversed boards.

Well I didn't go shoot. I broke the whole thing down and started with the baseboard to neg. stage; shimmed my column with two sheets of bond paper, retightened, and got it perfect with the laser thing. Two bolts were a little loose when I started. Then the lens stage. I backed the adjustment screws all the way out, put in a lens and aligned with the laser thing. Again, got it perfect. Lowered the head to 810 print height, then back up to 1620 print height and it stayed aligned. Managed to get through two negatives even though I started about two hours later than usual.

My confusion is still that one-sided OOF. I've always seen both sides out if it is that visible. (the Beseler 45 was my previous enlarger, lots of practice aligning that) Never perfect all the way across save one strip along the side. I might print again on Friday, if not, then Monday. My fingers are crossed that this will hold.

Thanks again for your suggestions, and please keep them coming! I'm still confused by this one.

[Renato Tonelli]

This sounds infuriating - I am at a loss at what could be causing the problem. I hope you will be able to solve it.

[bob carnie]

Is it possible that you are moving the easel to crop and the edges are out of the sweet spot of the lens, neg, bulb or box.

take the negative out of your enlarger, rack the lens way down so that you see a circle of the lens on the base board, Is it in perfect position of the blades of the easal , if not move the easal so that the circle matches the blades position,,, you now know that the lens , easel and light source are in a vertical alignment,
You now have to position the negative so that it is in this alignment, if you move the easel to match your neg position it could be causing an out of focus problem because it is not vertically aligned.

I assume you are using a glass carrier and negative popping is not your problem.
If the easel is not centered to the lens, and bulb , you will have problems.

[Jim Galli]

Sounds like a diffraction issue to me. The light is hitting an edge or a corner somewhere in the path and bending.

[Struan Gray]

Almost all alignment errors will give a blur that is symmetric across the central optical axis of the enlarger. That is, you see two blurred sides, or a ring of blur, symmetric about the middle.

Something is putting optical distance between the lens and the neg, and only on one side. It could be that the neg holder is allowing the film to curl upwards at one end, or, with a glass holder, that the bottom glass has shifted so that the lens sees a strip of clear negative with no glass in the way. However, my money would be on something transparent between the lens and neg stage - i.e. a piece of film or a filter which has fallen into the bellows which flops into view more easily when the bellows is compressed for the larger prints. If your neg holder or stage has masking blades there could be something there too.

Setup a negative as if you were about to make a print, check that the strip of blur is there, and remove the lens. Look upwards through the hole (or use a mirror) and see if you can see anything transparent obscuring the relevant side of the neg - i.e. the side opposite to where the blur is on the print/baseboard.