I would think that the paper size matters too. Going from 8x10 to 11x14 - you have about twice the paper area to cover with the same light intensity. Unless your test strips were at about the same enlargement grade.
- Thomas
Quote:
Originally Posted by srs5694
I've two anecdotes to contribute:
First, my Philips PCS130/PCS150, which uses three MR11 halogen bulbs (for red, green, and blue light), blew a bulb a while back. I replaced it with a spare bulb that came with the enlarger, but I found that I needed to radically up the output from the replacement bulb. When I looked more closely, I found that the replacement bulb was cloudy, as Richard notes. I don't know if the bulb was defective new or if it had been used, deteriorated, and set aside for emergency use only by the previous owner. In any event, it's worth checking the bulb for obvious discoloration/darkening.
Second, I mostly do 8x10-inch and smaller prints, but occasionally I do larger, so I keep some 11x14 sheets in my freezer. After about two years, I pulled these out to make some prints, but I did some test strips on newer 8x10 sheets of the same brand and type (Foma Variant 311 VC RC). When I went to make the final enlargement, I found that it was much lighter than my test strips on the same setting. I suppose this could have been due to emulsion-to-emulsion differences, but my suspicion is that it was the age of the paper -- even cold-stored, it seems to have lost speed over a 2-year period. As I recall, I needed to roughly double the exposure to get matching results.
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Please visit my APUG Portfolio - - - Wisdom I believe in: “Do not photograph what you see! Instead capture what you feel when the wind grazes your face, and the scents and sounds fill you with inspiration.” - Per Volquartz
I'm seeing my exposure times rise for exposing enlarging paper, Ilford Multigrade in this case. My times have risen at least 25% (e.g. an 8 second exposure now requires a 10 second exposure for the same results). I'm still working on the same batch of 500 sheets that I've started with last year
Note that a 25% drop isn't much - about 1/4 of a stop of light or 1/2 a zone of paper density - and there are a lot of things that can cause a variation of this amount: the utility is running the voltage lower; the last time prints were made the airconditioner wasn't running; the lens and or condensers are getting foggy; the aperture click stops are sloppy or the aperture ring was slightly off the stop; the developer is different; the developer temperature is different; the developing time is different; the wrong exposure was written in the original notes; if the enlarger is used a lot then bulb could be blackening, but that takes a powerful lot of use - the enlarger would have to be on for several hours a day for a regular ol' PH212, not nearly as much for a halogen lamp but still a lot of use, enough to have used up the 500 sheet box quite some time ago; the halogen lamp sockets could be failing - a pretty common problem.
The most likely culprit, though, is the paper is aging.
I spend a large part of my time testing paper for printing speed and characteristic curves.
I have been doing this testing for 4 years as part of Darkroom Automation's product development efforts.
And my experience is:
Paper will lose about 1/2 a stop of speed and 1/4 to 1/2 a grade of contrast in six months of intermittent usage. After this initial drop the paper stays relatively stable until it begins to develop fog. Paper that is removed from it's wrapping and spends a month or so in a paper safe is often a basket case with unacceptable levels of fog. My paper is kept in an air conditioned environment and never sees temperatures above 75F/24C.
If the paper package is unopened or the paper is tightly re-sealed and not re-opened it is pretty stable, as Simon says claims. Under typical amateur use this isn't the case.
This behavior is consistent and holds true for Ilford, Seagul and the old Kodak and Agfa papers. Forte, Foma and others are too inconsistent to make any statement about stability.
Since a loss of paper speed is well nigh guaranteed, it is the most likely culprit.
If you have a good enlarging meter you can check lamp stability over time.
If it were me I would shrug my shoulders, use 10 seconds, and not worry about it.
I would think that the paper size matters too. Going from 8x10 to 11x14 - you have about twice the paper area to cover with the same light intensity. Unless your test strips were at about the same enlargement grade.
Of course I didn't move the head; the enlargement factor was identical for the test strips and final print. I simply didn't want to devote an entire 11x14 sheet to a test sheet when I had 8x10 sheets handy, and 8x10 covered enough of the print area to tell me if the exposure and contrast was OK. As it turned out, though, my attempt at frugality cost me sheets, since the 11x14 had aged enough to make the papers rather different.
This brings up the topic of how long is the life and storage life of a halogen or incandescent bulb? Say you have a Durst bulb, an Atlas 110V 200W OPALE E27 P3/15 P 3/15 Lamp Bulb, and a couple of very old backups, are they good and how long are they going to be good? I bought a half dozen halogen bulbs for my Beseler 45, are they on borrowed time or is the proof in the printing? I use a rather large and heavy Sola CVA unit with my enlarger.
I got a whole box load of old halogen bulbs. So old the model on the box was wearing a 1960s/early 1970s outfit. They work fine if you look at the print. Does that mean they haven't dropped off some? Hell if I know. But then if the print is good why would I care?
This points out an interesting dilemma with printing records. I note every aspect of a print when I make it. Now I'm starting to wonder if it's worth it. I use a condenser enlarger with a regular incandescent 150W bulb.
- Thomas
__________________
Please visit my APUG Portfolio - - - Wisdom I believe in: “Do not photograph what you see! Instead capture what you feel when the wind grazes your face, and the scents and sounds fill you with inspiration.” - Per Volquartz
When I replaced the PH-140 75 watt bulb on my Beseler 23c II I found that the printing times were decreased by exactly one stop. If I reprint picture made with the old bulb, I'll just have to compensate base exposure and burning/dodging times by one stop which isn't too much of a convenience. Paper speed between different batches of ilford are very consistent. However, once when I opened a new pack of Foma Fomatone 132, I found it to 1/3 stop slower that the old pack I was using.
I have been doing this testing for 4 years as part of
Darkroom Automation's product development efforts.
I've an Ilford EM-10 enlarging meter; under $30. Darkroom
Automation has much more of a meter; under $100. Ilford's
is a very compact pointy unit but lacks any read out and
is none linear in response while Automation's has all the
bells and whistles but is more bulky.
How about an under $70, linear with read out, very
compact, enlarging Light Meter? Dan
This points out an interesting dilemma with printing records. I note every aspect of a print when I make it. Now I'm starting to wonder if it's worth it. I use a condenser enlarger with a regular incandescent 150W bulb.
- Thomas
This something I stopped doing some years ago. I had found that when returning to an old negative to reprint it I almost always had to revert to basics due, I suspect, as discussed here to changes in bulb condition, paper batches, chemical changes etc. The etc includeds several enlarger and lens changes by the way; which may have had a slight effect on the process.
Linear Mode
