Ian, my guess is that yes it would. But there is an easy way to find out. Just do the test. By doing this you will find out if your bulb throws a glitch into the system, which will be worth knowing anyway.
When I used a fluorescent light in a home-made 5x4 enlarger, I found it was the highlights that stayed constant across the grades, not the mid-tones. And the difference in contrast between grades wasn't an even jump between grades. When I switched to LED bulbs rated 2700K I got the results as described above - an identical result to that which I'd previously got in my 35mm Leitz Valoy enlarger with a traditional incandescent pearl bulb.
I suggest that as Ian will be using the same enlarger for Alan's useful exercise and for his prints, the precise colour of the lamp does not matter. If he were using two different enlargers, then this might become important. There will still be noticeable differences between each grade and on the same enlarger, they will be consistent.
A new lamp or a new enlarger might change things, of course.
It's sold as a standard enlarger lamp, for a variety of well-known enlargers. I can't see it causing any major problems. In any case, there's nothing to compare with, unless Ian has a reflection densitometer and intends to do some very precise testing. Even if he did do that, it's hard to see what use it would be in any actual printing situation. We print with our eyes, not by numbers.
I'm looking forward to seeing the results of the test. It's the kind of thing I've promised myself, but always put off until another week.
More amusing light bulb jokes please.
(Alan, for completeness only, I'm adding that that your 10 seconds is an example and normal test-strips will be needed for the first, No 2 print. I hope you don't mind.)
Having read Alans information, I decide to try something.
Here are 2 prints, one was done on Grad 2 1/2 and the other done on Grade 5
Grade 2 1/2
The Grade 5 was 12 seconds @ f/8 on the enlarger. I can see detail everywhere in the shadows at 12 seconds, anything higher than this then I lost the detail in the deepest areas under the larger wheel on the right.
Because I am having to get some contrast at Grade 5 and can see good detail in the negative, I am thinking in the terms that I might not be agitating the tank hard enough during the development stage. Does this seem plausible ?
Ian, if you need to go to Grade 5 to get a print with nice contrast and detail in the shadows and highlights then your negative definitely needed more development; either more agitation or more time in the film developer. Personally I would decide on an agitation regime and stick to it.. and change the amount of development by changing the time.
There is nothing wrong with printing on Grade 5, but you run out of shuffle room if you need even more contrast. For this reason most people try to produce negatives that print on Grade 2 or 3.
They don't look two and a half grades apart on this screen and neither looks like Grade 5. That should be soot and whitewash. How long was the paper developed for? It could be exhausted or cold developer. It doesn't keep. For any kind of testing, fresh developer is essential.
Your testing for personal EI and N development should have taken into account your agitation technique.
Agitation is what it says. There's a very thin layer of developer next to the emulsion which rapidly becomes exhausted, but it still clings to the surface, shielding the film from further action. When you agitate, turbulence should scrub this off and re-mix the whole volume of developer, so that the emulsion has fresh solution next to it. That becomes exhausted in turn and needs more turbulence to re-mix the solution and continue the process.
When you agitate, are you vigorous enough to re-mix the whole volume of liquid?
We standardise on a pattern of agitation (typically for the first 30 seconds and then every half-minute after that) to control the degree of development. Continuous agitation causes the film to be exposed to fresh developer all the time and so less time is needed. Rotary processing typically needs 15% less time but this is always subject to individual experiment. All darkroom processes are subject to individual testing.
If we do not agitate, we run the risk of uneven development, but it is claimed that the most exposed parts of the negative exhaust this thin layer more quickly or more completely and therefore cease to become denser. Meanwhile, the less-exposed parts continue to develop, albeit more slowly. This is considered to be a useful tactic in controlling contrast. Other effects on the transition boundary between light and dark are claimed but that's another matter entirely and needs to be treated separately.
David, yes, 10 seconds was an example only. I think the best way to do this test is not to set out to do it, but have it up your sleeve for when you are in the darkroom and have just done a nice print on Grade 2, 2.5 or 3, i.e. a middle grade, with no burning-in or dodging. The negative is in place and focussed. You know the enlarging time because you have just made the test strips and come up with a nice print. All you need to do is make prints at all the other contrast grades, in whole grade steps. (half grade steps if you really want to, though they aren't really necessary) Done like this the test doesn't take much time to do, and doesn't waste any paper.
We know that Ian can print perfectly well digitally, so a digital print would show if this negative is faulty. If he took the naked scan into Photoshop, with no adjustments of any kind at all and posted a screen grab of the Levels panel we could see if there were any glaring negative faults.
This negative seems to have shadow detail, so exposure is adequate. The highlights don't seem blocked so it's not overdeveloped. But they don't look like grade changes. They look like 8- and 12-second exposures at the same grade. (Which seem rather long for a 5x7 print. Can the neg be fogged? Does it pass the newspaper test?)
Both prints look as if they are snatched or that Ian has been trying to re-use some used print developer. In this weather, it seems unlikely that it was too cold. Accidentally using a dish for the developer that had previously held fix or stop might produce this effect. Either that, or the safelight problem is still unresolved. What paper is this? Did it come from eBay?
In another thread, Ian chides us for not calibrating our monitors. The basic Zone System tests for personal EI and Normal development time are the equivalent of monitor calibration. There is plenty of published advice out there already so there's no need to re-iterate it here. It can be done without a densitometer and Ian's technique is not yet refined enough to need that kind of precision.
For beginners, a very good substitute for the Zone System is to read the instructions on the packet and follow them.
I have to admire Ian's getting into what looks like a very interesting place for photographers. There's an excellent picture lurking behind the print problems.
There should be a much greater increase in contrast between the two prints, regardless of any negative issues. I think I have swatch in a US Kodak publication of the same print made at different VC grades, I'll look tomorrow. It's actual prints not reproductions if I still have it.
I did mention before having issues just like this in a small darkroom, I couldn't get more than about grade 3.5 and it was a safe-light issue, one mentioned in a couple of magazines at the time. Paterson/Photax introduced a VC filter for their safe-lights.
I did mention before having issues just like this in a small darkroom, I couldn't get more than about grade 3.5 and it was a safe-light issue, one mentioned in a couple of magazines at the time. Paterson/Photax introduced a VC filter for their safe-lights
I would be suspicious of the safe-light, it's something quite rare and really is only ever an issue in very small darkrooms. The Paterson safe-light that caused me problems was one I'd used for well over a decade in larger darkrooms.