Enlarger Issue

[Mark Whiting]

I am trying to become familiar with a new (to me) Beseler 45MCRX enlarger with an Aristo Cold Light head. I made a couple of prints with an EL Nikkor 135 mm lens. I was unhappy with the prints so I checked for even illumination. I set up the enlarger for a 16 x 20 print, removed the negative and measured illumination on a piece of white paper with a 1 degree spotmeter. The readings were:

EV3 in the center

EV2 1/3 at the center of the four sides

EV1 2/3 at the four corners.

This looks pretty bad to me.

I then checked for even illumination with an 80 mm Rodagon and a 6x6 neg holder. I set up for an 11 x 14 print, removed the neg and checked illumination on a white piece of paper. The readings were:

EV2 in the center

EV2 at the center of the four sides

EV 1 2/3 in the corners.

This looks a lot more reasonable

Questions:

Is the light fall off on the 135mm lens normal? Is it a lens problem or an enlarger problem? I have the cold light head all the way down.

Should I switch to a 150mm lens? With a 150 mm lens what is the distance from the negative plane to the image plane for a 16 x 20 print? One of the reasons I switched to 4x5 is to be able to make 16 x 20 prints.

[Leonard Robertson]

Mark - Is the upper bellows racked all the way up, so the negative is as close as possible to the cold light?

[Mark Whiting]

Yes, the cold light head is as close to the negative carrier as possible.

[ramin]

Mark:

Stop your EL Nikkor down to mid apertures and you will get a more even illumination although still not perfect. In real practice though you should only notice the edge light fall off if your negative is very thin. Cold light heads are supposed to be very homogeneous in illumination but in fact they are not. I heard that Zone VI is planning to replace its cold light head with LED light source. Eugene where are you?

[Armin Seeholzer]

Hi

I like the even ilumination of my Jobo (Sanders) LPL only a f 1/10 less at the cormers then in the middle!

[phil sweeney]

Mark,

The problem is lamp size and optics. A 150mm would do better. I have a MXII and use a 150mm. With that setup I still have falloff problems. A few years ago I made a correction mask that counters the uneven illumination. It is the perfect correction. Unfortunately many enlargers' lamps are smaller than what would be ideal. Before I made the mask I had contemplated getting a 5 x7 or 8 x 10 enlarger. Depending on how I rotate the lamp the character of falloff is different so I marked the lamp housing to keep it oriented in the same position always.

Many people claim they can compensate for the falloff with corner and edge burning. I could too, in most cases, but there many images I could not get it perfect.

If you want to see how bad it really is expose a paper, as described in "The Print" (page 20).

[Tom Westbrook]

At John Sexton's basic printing workshop I attended last year he had some "prints" he made by just exposing paper with an empty negative carrier. They were just straight prints he exposed so they came out at about a Zone V at darkest, maybe Zone VI. He did that using a Besseler with a cold light (not sure which model, but probably Zone VI), a Durst and an LPL. On the print from the Besseler you could see a fair amount of uneven illumination, and you could even see the shadow of the coils of the cold light tube. The other two brands showed very even illumination (the Durst actually appeared to add a bit of edge burn for you!). I believe he used a 150mm lens.

I tried the same experiment when I got home on my own Besseler 45MCRX outfitted with an Aristo V54 cold light. I got pretty much the same results (I used a 150mm lens).

Since John used a Besseler for quite a while, I believe, before he switched to LPL, I would guess that it's an issue you just have to learn to compensate for unless you want to buy a better enlarger. He did mention that he had a friend create a reflective center filter digitally, printed it on white paper and mounted it above the cold light tube to even out the illumination. Supposedly that helped a lot.

[Henry Ambrose]

I had an Elwood 5X7 enlarger that was missing the ringed opal glass that evened the light over the frame. After several attempts I made a "center filter" on an inkjet printer that evened the light nicely but the heat form the 250 watt bulb made printing troublesome. Before that I had a cold light head on a Beseler 4X5 that was a real pain to print with - hard to get any consistency out of that thing - I had to use a card to cut the light on and off. Eventually gave up on the Elwood too and bought an LPL4550. I've been very pleased with the LPL. I can "fix" lots of things but there's no point in wasting my life on a funky enlarger thats a poor design.

[MIke Sherck]

I have a very old beseler 4x5 with an old D2 cold light and use a Rodagon 135mm lens. There's a white plastic diffuser disk and a yellow filter which came with the cold light. The whole thing is rather kludged together using the filter drawer from a newer Beseler 4x5 enlarger, the D2 cold light, and an aluminum adaptor ring to get the cold light to huddle comfortably just over the filter drawer, etc. but it seems to work pretty well. Illumination at the edge of a 16x20 print is only -1/3 stop from the center. Printing times are rather long (30 sec. f/8 is typical for 11x14, for example, and it takes a good 1/2 hour for the D2 to warm up,) but I'm told that's reasonable for old cold lights. I just wish I had a better place to store the condensors I took out when I removed the old enlarger head and it's 150w light bulb... :)

[Gem Singer]

Hello Ramin,

I just checked the Calumet website, and they are still saying that their new LED lamphouse is overdue from the supplier. From the information they are furnishing about the LED, it looks like it is only being made to fit their Zone VI enlarger (4X5 and 5X7?).

Hi Mark,

I do not believe that the falloff problem you are experiencing is being caused by the EL Nikkor 135 lens. I have been using that lens for many years to make 16X20 enlargements from 4X5 negatives. It easily covers the 4X5 format when the negative is centered in the light path and the enlarger is properly aligned. I like the 135 focal length because I don't need to raise the enlarger head as high to focus for 16X20's. Using a 150 increases the distance between the eyepiece of my grain focuser and the focusing knob of my enlarger, making it difficult to reach, and they don't make a suitable focusing extension for my old D-2.

It sounds like the Aristo is not emitting light evenly over the entire negative. We used to call those round Aristo cold light replacement lamps "snakes in a flower pot". The problem could be caused by improper placement of the cold light unit in the enlarger, the opal plastic light diffuser may be missing, or the cold light tube may need replacement. A call to Aristo may be in order here. The tech staff at Aristo was always eager to help solve any problems I was having with their products.

[d.s.]

Mark,
I bought a used Zone VI head and the prior owner had made a disk out of grey mat board (two or three inches in dia.), and inserted it behind the tube. Due to poor packing, the unit arrived with a broken tube and I replaced it with a V-54. I removed the mat board but kept it because I wasen't sure what it was for. Now I know and will check mine for light falloff / uneveness.

It just pays to read all these threads. You never know what you'll learn.

dee

[Brian Ellis]

I used an Aristo VCL 4500 head on a Beseler MXT enlarger and a Schneider Componon S 150mm lens for many years, always one or two stops down from wide open. I never noticed any consistent fall-off at the edges of my prints.

[Gem Singer]

Brian,

The Aristo VCL 4500 cold light head is a designed differently than the Aristo head that Mark is referring to. The 4500 has two tubes encased in a larger sized box, as well as a double diffusion screen on the bottom. It emits a more evenly diffused light pattern than Mark's single tube "snake in the flowerpot" type of Aristo cold light.

[Eric Wagner]

The problem is not your lens or the enlarger. It is the Aristo unit, which is smallish for a 4x5 negative because it was sized to be the same size as the Omega and Bessler condensors in order to fit those enlargers. I give a 15% burn to the edges of the print, which adds twice that to the corners. Edge burning is not needed with smaller negatives. It does help to use a longer lens. It will be about 30" from the lens to the paper to make a 16x20 with a 150mm lens. I use a 180mm, and it is about 36" from lens to the paper to make a 16x20 with it. Don't forget that this enlarger can be used for wall projection for really big enlargements. Someone above mentioned being able to see the shadow of the coils on a test print made without a negative in the carrier. I have the standard lamp and do not have that problem, but I have heard that can happen with the high intensity lamps. I believe Fred Picker used to solve that problem by using two sheets of opal glass separated by a small air space. That solution might reduce light falloff at the edges too.

[Joe Hunt]

On the other hand it might save you the bother of using a centre filter with wide angle lens on camera!

[Richard Schlesinger]

I am using the identical setup (Aristo head, V54 lamp, Beseler MCR enlarger) and have not experienced the problems you are having. Ctien, in his book "Post Exposure" has a section (page 61) addressing the problem of uniformity. He indicates testing for uniformity of illumination is better done using paper and making prints. He describes his method, stating that using a photometer it is". . . extremely difficult to align one to eliminate errors introduced by off axis measurements." Check out his book. I have found it very informative and have had some e-mail exchanges with him in which he has been very helpful.