Problem during first printing session.

[WILL WORK FOR FILM]

I have finally brought my bathroom darkroom up to operational status and had my first printing session yesterday. I had the usual "just getting started" issues and worked through them. managed to get a handful of decent 8x10 prints using inexpensive RC papers. But, I have noticed what seems to be a slight problem with my Besler 23c11 enlarger. Almost every print has what seems to be an underexposed portion of the bottom two corners in a radiused shape. I stopped and made a contact print of the entire 35mm roll of negatives to see if it was just light spots on the negatives. They look good. Then I made sure that the head was level and looked for light leaks and anything that might cause this and made another print with the same results. I am baffled. And the strange part is that I am not getting the same result on every print.

Has anyone experienced this problem?

 

[winger]

Something is blocking the light probably. Are your filters all the way in? Is there anything extra in the filter drawer blocking the light? There is a frame that holds the filters - is it facing the right way? Is the condenser in the right position for the film size?

 

[Rick A]

Is the condenser head set to the correct format?

 

[WILL WORK FOR FILM]

I am using Ilford VC filters (5.5") and yes they are in correctly with the filter drawer properly installed. As far as the condenser being set for the right format, I don't know. Please clarify this. Just might be the problem.

 

[removed account4]

if you take off your lens look through it wide open and stopped down
are the blades of your iris working correctly sometimes a rivit pops
and a blade obstructs the light path ... also turn your enlarger on ( dim bulb is OK )
and look with your head on the enlarger easel UP into the enlarger head .. do you see anything obstructing your view ?
might be the filter drawer or holder under the lens or something like that ..

 

[Rick A]

I am using Ilford VC filters (5.5") and yes they are in correctly with the filter drawer properly installed. As far as the condenser being set for the right format, I don't know. Please clarify this. Just might be the problem.

On the right side of the condensers, there is a scale that points to the format, move the head up or down until the indicator points to the format you are using(35mm,6x6, 6x7,6x9).

Dead Link Removed

 

[Alan9940]

Sounds like vignetting from the lens, but I don't understand why it's only the bottom two corners affected, if truly vignetting. What length enlarging lens are you using? Shorter than 50mm can cause light falloff in the corners, unless using a shorter lens specifically designed for 35mm format such as a Leitz Focotar 40mm. Proper functioning of the aperture blades, mentioned above, is a good thing to check. I would suggest putting an empty neg holder into your enlarger, turn the light on, then measure the corners and, maybe, a couple of other points with a light meter. I would do this at various apertures of the enlarging lens, especially apertures you typically use for printing. The light meter readings at any given aperture should be pretty close to or the same exact values.

 

[WILL WORK FOR FILM]

Sounds like vignetting from the lens, but I don't understand why it's only the bottom two corners affected, if truly vignetting. What length enlarging lens are you using? Shorter than 50mm can cause light falloff in the corners, unless using a shorter lens specifically designed for 35mm format such as a Leitz Focotar 40mm. Proper functioning of the aperture blades, mentioned above, is a good thing to check. I would suggest putting an empty neg holder into your enlarger, turn the light on, then measure the corners and, maybe, a couple of other points with a light meter. I would do this at various apertures of the enlarging lens, especially apertures you typically use for printing. The light meter readings at any given aperture should be pretty close to or the same exact values.

I am using A beslar 50mm f3.5 that most likely came with the enlarger. When I bought this enlarger (of the BAY) it looked brand new and well taken care of. While inspecting it the glue holding the bellows in place separated. I took the condenser and bellows completely apart and cleaned all surfaces and re-attached bellows with E6000 epoxy. I am also wondering if maybe one of the condenser lenses might not be sitting perfectly parallel in the lens holder.

 

[JensH]

Hi,

I had something like that when the bulb in my Durst enlarger was not properly alligned after replacing it.
Maybe there are screws to correct it if necessary.

Best
Jens

 

[WILL WORK FOR FILM]

Well it seems that this was probably just a classic ROOKIE move after all. The top bellow adjustment has 3 approximate settings. 8,16,35mm / 2-1/4 x 2-1/4 / 2-1/4 x 3-1/4. It was just above the 2-1/4 x 2-1/4 setting. So basically I had it set for medium format negatives. It has been re-deployed to the 8,16,35mm location. This what happens when the new guy tries to figure it out without the user manual. I'm glad I asked before taking the head apart on a witch hunt. I will give it a try tonight and verify what I believe will be the fix.

Also, is it necessary to use the clear plastic shield over the contrast filters? The one I have is warped and barely fits into the filter drawer so I haven't been using it.

 

[tedr1]

No shield is needed.

 

[Alan9940]

Hey, we all make rookie mistakes even after years of experience. Glad to hear thst you've most likely solved your issue.

 

[WILL WORK FOR FILM]

Problem solved. Spent a few hrs in the darkroom last night and the results are much improved. I have depleated my first box of Ilford MG 1V RC deluxe 8X10 and am contemplating breaking into the stash of MG FB Classic that has been laying around for a while. Feeling a bit nervous about the washing process though.

 

[Rick A]

If you are using a hardening fixer you have long wash time. If you are using a "rapid" or alkaline fixer you will have much shorter wash times. Using a wash aid (hypo clearing aid)will reduce times even significantly. I recommend a wash aid and following the instructions provided by the manufacturer.

 

[WILL WORK FOR FILM]

I will be using Ilford rapid fix and Kodak hypo clear. Just looked at the Ilford site and was pleasantly surprised to see that the procedure is significantly reduced with a wash aid. I will now dive right in. I intend to hang the prints to dry. Any tricks for getting Ilford MG FB classic flat?

 

[winger]

Any tricks for getting Ilford MG FB classic flat?

That's what coffee table books are for. There is a sticky thread somewhere here about flattening FB prints. I use a dry mount press for ones I'm going to mat and frame, but I don't go that far with "regular" prints. What gets them reasonably flat is putting a few facedown between clean pieces of mat board and then putting something heavy on top, like coffee table books. Old chemistry books work, too, but they aren't big enough for 11x14. I store prints in acid-free boxes (the kind with the metal reinforcements on the corners). Once there are enough, the weight makes the bottom ones pretty flat, too.

Glad you solved it! As you might guess from my list at the start, you may not be the first to do that. Which is part of why APUG is such a great place - we all messed something up before.

 

[tedr1]

Glad you found the solution.

I note that you described the two lower corners being affected, this presumably means there was no effect at the top corners. this suggests there is a misalignment somewhere in the system. When everything in the light path is centered the corner shading (vignetting) should be equal in all four corners. Sometime when you are not busy it is worth investigating this further, the goal is to have the two condenser glasses, the negative mask, and the lens, all centered above one another.

There is another cause of uneven corner illumination that you may come across, this is due to inherent limitations of the lens and is most evident when the lens is wide open (for focusing) and less evident when it is stopped down for exposure, but may still be enough to cause the corners of a print to be a little too light. One remedy is to burn in all four corners, this may be done by giving the paper an additional exposure with an opaque mask in the light path that covers everything except the corners.

 

[WILL WORK FOR FILM]

Glad you found the solution.

I note that you described the two lower corners being affected, this presumably means there was no effect at the top corners. this suggests there is a misalignment somewhere in the system. When everything in the light path is centered the corner shading (vignetting) should be equal in all four corners. Sometime when you are not busy it is worth investigating this further, the goal is to have the two condenser glasses, the negative mask, and the lens, all centered above one another.

There is another cause of uneven corner illumination that you may come across, this is due to inherent limitations of the lens and is most evident when the lens is wide open (for focusing) and less evident when it is stopped down for exposure, but may still be enough to cause the corners of a print to be a little too light. One remedy is to burn in all four corners, this may be done by giving the paper an additional exposure with an opaque mask in the light path that covers everything except the corners.

Very interesting. how would you go about this opaque masking technique?

 

[tedr1]

This is a practical skill that produces good results by simple methods, it is a type of burning-in process to darken the corners.

Assuming an 8x10 print size find a piece of thin card (the more opaque the better) about the size of the palm of your hand, cut off the corners, attach some sort of handle, perhaps some twisted wire, a popsicle stick, or a drinking straw. This is the mask, it is used to cast a shadow on the paper. It is held below the lens about half way between the paper and the lens, the distance doesn't matter very much, change the distance to make the shadow the right size to cover most of the center of the image on the baseboard. Experiment with white paper on the baseboard to get the appropriate distance and make a mental note.
After the print has been given the predetermined correct primary exposure turn off the lamp, leave the paper in the easel and pickup the burning mask. Hold the mask at the right height and location that were determined earlier to cast the desired shadow, turn on the lamp, shake the mask up and down, side to side and to and fro, turn off the lamp. The exposure needed to darken the corners varies depending on the amount of vignetting due to the enlarger, as a guide somewhere between one quarter of the primary exposure and an equal amount to the primary exposure may be used for experimentation (approximately one quarter stop to one stop additional exposure). The purpose of the shaking motions is to prevent the production of sharp edges by the mask on the paper.