Bad lamp.

jstraw · Mar 23, 2007

Boy do I feel stupid.

It finally dawned on me that I've been having to burn in all my prints from 4x5 negs in the same areas. So I got suspicious about an uneven light source. I focused the bare lamp onto my baseboard and grabbed the lamp housing and rotated it and could clearly see dark patches following the rotation. Only then did I lift the housing and actually look at the lamp.

Let's just say that I was jumping trough needless hoops printing...and a lot of print recipes will be out the window now.

The upside is that I'd already ordered a new D2-HI-V54 from Aristo for unrelated reasons. Yeah, I know...those print recipes are out the window anyway.

I never noticed this with the 6x6 negs because the problem isn't apparent in the center of the lamp.

My lamp must be about 19 years old. If yours is of a similar vintage you may want to check and see if it looks anything like this one...

(note: what you see is all on the inside of the tube, not the exterior surface)

Sparky · Mar 23, 2007

What if you used another layer of diffuser (plexi) underneath - surely you could get it CLOSE to even... (just as a purely academic argument! - certainly it's time to put the old one out to pasture - but if you needed a quick fix...!)

jstraw · Mar 23, 2007

Sparky said:
What if you used another layer of diffuser (plexi) underneath - surely you could get it CLOSE to even... (just as a purely academic argument! - certainly it's time to put the old one out to pasture - but if you needed a quick fix...!)

Thought of that and thought of actually moving the lamp further from the diffuser as well. Bottom line is that I'd already coincidentally ordered its replacement.

Sparky · Mar 23, 2007

Right. makes loads of sense. I only responded because I had similar issues on my mind. I just converted my DeVere dichro to cold light, and was messing around with diffusion (I didn't have a decent diffuser - and found that orbital-sanded double plies of clear plexi didn't do a whole lot to get rid of the 'grid' pattern).

patrickjames · Mar 24, 2007

My thought is to chuck it. Life (and darkroom time) is way to precious to waste on substandard equipment and I would go as far to say that in this day and age you should only be using the best, because the best is really cheap now that no one wants it.

Patrick

jstraw · Mar 24, 2007

Consider it chucked. I won't be printing again till the new lamp arrives.

Fo the sake of interest, here's what an un-burnt print made with the bad lamp looks like. This is full frame.

MurrayMinchin · Mar 24, 2007

I had the same experience with a cold light, but was lucky to discover the problem right away because the first print I made was of a wide waterfall. The negatives exposure was quite long, so there were large areas of even high values which showed bands of dark and light print values.

It took some head scratching but I got a slam-dunk diagnosis with the following test. Focus a negative in the enlarger then remove it. Place a piece paper in the easle and give it enough exposure to print as a lightish grey at a bit more contrast than 'normal', then process the paper. In a perfect world the paper should be of a smooth, even tone from edge to edge and corner to corner.

I was shocked at how uneven the print was! As suggested earlier, a piece of plexiglass above the diffusion disc did the trick but came at a cost...it lengthened exposure times and created fall-off at the corners which had to be compensated for while printing, but at least it was smooth.

I'm getting a new light source soon, and that test is the very first thing the light is going to do.

Murray

jstraw · Apr 4, 2007

Well, my new lamp is installed. It was a breeze to do, though I was very nervous about the little bit of flexing it went through to get it into place. It's actually the second D2-HI-V54 that was shipped. The first broke in transit which is surprising because I can't imagine that it could have been packed any better than it was. Aristo sent a replacement promptly and asked no questions.

Some observations:

The "HI" lamp is SO much brighter. It now stabilizes at "L" whereas the old lamp stabilized at "F" on the Zone VI stabilizer.

The V54 is SO much more cyan than the old lamp with corrective yellow filter. I knew any previous print recipes wold be irrelevent but it's astonishing how the yellow and magenta created with split grade filters are so much more yellow and so much more magenta.

I'm looking forward to being at square one.

The light is still a little uneven, though much, much less so. If I focus the round light beam onto the baseboard, I can still detect variations if I rotate the lamp housing. Most of the dimmer areas would be masked by the negative carrier. I may still think about adding another diffusion disk.

greybeard · Apr 4, 2007

In principle, at least, you could make a mask, using some reasonably linear film/developer combination. I have seen reference to this before, but never tried it myself. My guess is that it would take a lot of neutral density between the lamp and a sheet of film (possibly litho stock) to get a manageably short exposure, and then development to a fairly low density. (It is my understanding that this was once done for large contact printers used for things like mass-production of architectural photos.)

jstraw · Apr 4, 2007

greybeard said:
In principle, at least, you could make a mask, using some reasonably linear film/developer combination. I have seen reference to this before, but never tried it myself. My guess is that it would take a lot of neutral density between the lamp and a sheet of film (possibly litho stock) to get a manageably short exposure, and then development to a fairly low density. (It is my understanding that this was once done for large contact printers used for things like mass-production of architectural photos.)

This went right over my head. Sorry. What problem would such a mask address?

greybeard · Apr 5, 2007

jstraw: Sorry--I should have been more clear.

If you make a "contact print" of your lamphouse onto film, the brighter areas of the lamphouse will be darker on the film, and the less bright portions will be lower in density. In principle, putting this "mask" in registration below the lamphouse during printing will even out the exposure across the field, because the brightest parts of the lamp will be behind the darkest parts of the mask, and vice-versa. Getting the right density and contrast is the tricky part, and as I said, I have not tried it myself.

The whole process is comparable to the making of positive and negative contact masks for correcting density and contrast; at one time, this was common enough that Kodak made a film---Pan Masking Film, I believe---specifically for doing this with large-format color images.

jstraw · Apr 5, 2007

ah...I see...thanks for the explanation

Sparky · Apr 5, 2007

It's curious, J. RIGHT after you made that post and I'd responded... I ran into the same problem with my new cold light. I'd done some pretty major modifications to the housing (cutting) to get it to fit into my lamphouse. After the first several prints - I started noticing the same thing as you had. It was corrected by raising up the cathode (tube) into the shell in what is probably it's proper position - about half an inch up. Before it was sitting DIRECTLY on the plexi diffuser.

jstraw · Apr 5, 2007

Mine has a metal spring clip in the center of the housing that holds the tube...once the tube is snapped into that, it can't go any higher. If I need it higher than that, I'd need to work out a way to raise the whole housing...which I can do relative to the neg by extending the top bellows a bit...but that won't raise it relative to the diffuser. that would require some creativity.

removed account4 · Apr 5, 2007

hi jstraw

have you talked to rick at aristo about your problem?
i had trouble with my lamp when i first got it, and sent it to him for tests.
he was very helpful in troubleshooting.

the d2-hi is the high output lamp that puts out 2x the light as the regular bulb.
if your film is not dense enough, you will need to stop down all the way,
or get a dimmer ( aristo sells those too ) to cut down the light output.

all my film was developed for printing with a condensor,
so i had to get a dimmer when i switched to the cold light head.
i still don't really like the cold light heads ( i have 2 of them ) and will
probably go back to using the condensors. they give my prints "snap" that
the neon tube doesn't give.

good luck!
john

jstraw · Apr 5, 2007

jnanian said:
hi jstraw

have you talked to rick at aristo about your problem?
i had trouble with my lamp when i first got it, and sent it to him for tests.
he was very helpful in troubleshooting.

the d2-hi is the high output lamp that puts out 2x the light as the regular bulb.
if your film is not dense enough, you will need to stop down all the way,
or get a dimmer ( aristo sells those too ) to cut down the light output.

all my film was developed for printing with a condensor,
so i had to get a dimmer when i switched to the cold light head.
i still don't really like the cold light heads ( i have 2 of them ) and will
probably go back to using the condensors. they give my prints "snap" that
the neon tube doesn't give.

good luck!
john

Zone VI head, Aristo won't touch it. I'm lucky the lamp even fits. Aristo SWEARS they didn't OEM the Zone VI heads. I don't believe them...that's another story.

The Zone VI stabilizer is a dimmer only better...so I can turn the light way down if I need to.

The "anomalies" are in the shape of the tube. I think the issue is this...the tube sits so close to the negative that if the negative is in focus, the tube can't ever be completely out of focus. I suspect that the only real solutions would be either to get the tube further from the focal plane of the negative (which may cause vignetting) or to increase diffusion.

jstraw · Apr 8, 2007

Here's the first print with the new lamp...

(there was a url link here which no longer exists)

It really is bright. I mentioned before that the old lamp stabilized at "F" and that's where I printed with it set. The new lamp will stabilize all the way up to "L" and give you a pretty decent tan at the same time.

This print and some proofs I cranked out were done ad "D" to slow it down to manageble times. The proper proof time for my negs at "D" is 6.7 seconds.

This print had a soft exposure of 13.4 and a hard exposure 19.2. There are no dodges or burns in this print but at those times they'd probably be manageable though I could see dimming the lamp even further.

The illumination is much more even than on the old, bad lamp.

jstraw · Apr 8, 2007

I should say that my scanner seems to increase contrast. In some respect this scan is punchier than the print and I would like to be lest timid with the hard exposure and get some more punch in the print...and will. But it also is exagerating the blown out spots such as the area just below the bare bush near the right edge and the slope in front of the far dish.

donbga · May 23, 2007

jstraw said:
Consider it chucked. I won't be printing again till the new lamp arrives.

Fo the sake of interest, here's what an un-burnt print made with the bad lamp looks like. This is full frame.

Hmm, I always thought you had uneven film development. Good luck with the new light source.

jstraw · May 23, 2007

Nope, my film was fine. It sure is good having a functioning lamp.

Daniel_OB · May 28, 2007

Distance lamp - condenser is not the same for different negative size. Also it is not bad practice to place a tracing paper (one like mat focusing glass on the view camera) between the lamp and the condenser (after proper lamp position is found).

www.Leica-R.com

jstraw · May 28, 2007

Daniel_OB said:
Distance lamp - condenser is not the same for different negative size. Also it is not bad practice to place a tracing paper (one like mat focusing glass on the view camera) between the lamp and the condenser (after proper lamp position is found).

www.Leica-R.com

Cold light heads have no condenser. The distance between a cold light source and the negative does not change for different formats. Cold light heads such as mine incorporate a sheet of white plexiglas as a diffusing element. A sheet of tracing paper would contribute nothing.

Thanks though.

Bad lamp.

jstraw

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