The whole, don't use cyan has slipped me mind actually....
The lamp is realy almost new.
I will look at my filtration, allthough I am far away from f8 @ 15 sec.
I had a new lamp which lasted for about an hour before it died so although rare it's possible it's the lamp. You may be able to tell from looking at the lamp - they tend to get extremely hot (more so than usual) as they fail and you can sometimes see the consequences. The only other possibilities are enlarger/head/lamp alignment, filtration, bad paper/chemistry or a rather dense negative. For comparison Ilfochromes with my 100W enlarger, 6x7 mixing box, 35mm negative with email@example.com lens a 8x10 print typically takes around 20 to 30 seconds. With the 250W enlarger and a 35mm mixing box I'm down to less than 10 seconds.
A typical 8x10 from 35mm with a 35mm mixing box and a lamp of that wattage would be about 12" at f8 - 16 with a filter pack of 40Y, 40M, 0C. This is with Endura type paper. The keeping should not be a significant factor in this.
If you are using a combined C,M,Y filter pack then the speed loss would be equal to the cyan filtration plus a bit. So 60 cyan in the beam is about 2 + stops speed loss if there is M and Y filtration. If you are using a mixing box for 4x5 for 35mm you will lose over 2 stops.
If you were using Ilfochrome paper, I would expect the type of exposure and filtration you are using.
I use 38 deg C (100F) for 1' with RA-RT developer replenisher in a jobo, or 2' at 68F (20C) in a tray with the RA-RT developer replenisher.
Did you install it? Is it seated correctly?
Originally Posted by game
I believe the correct spelling is "reciprocity failure." This refers to non-linearity in the exposure characteristics of a film or (in this case) paper over time. In other words, a 10s exposure at f/8 (to pick a random value) may not be equivalent to a 20s exposure at f/11 or a 40s exposure at f/16, even though they should theoretically be the same. Modern films are designed to not encounter significant reciprocity failure over common exposure times. I don't know much about the reciprocity characteristics of paper, but the suggestion was that a 2-minute exposure might be running into this limit. The result would be that you might need an even longer exposure than you'd think -- or alternatively, if you increased the light hitting the paper (say, by opening the aperture a bit), you could decrease the exposure time by more than you'd expect -- say, to something less than 30s if you opened up by two stops.
Originally Posted by game
One other note: Different color layers in color film (or presumably paper) have different reciprocity characteristics. Thus, reciprocity failure can result in color shifts as well as the need for modified exposure in color materials.
The optimum aperture depends on the lens, but in general it's about 2 stops down from the maximum aperture. I believe the suggestion to try a wider aperture was as much for diagnostic purposes as anything else. If you open up (say) two stops and find that you can then get good results with, say, a 15 second exposure rather than the 2 minute exposure you require now, then you know you've run into reciprocity failure -- either that or there's something weird going on with your lens. Speaking of which, that's another possible source of problems -- check to be sure that the lens is clear and that the aperture blades open and close as you'd expect when you adjust the f-stop setting.
2. I have always been thought that when enlarging the lens should preferably be on f8 or smaller. Never fully opened...
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
Tommorow I will indeed check if the lens is clean. I'll open up the aperture to check repricio.... failure. And will use zero cyan filtration.
Two things. At first I use 33 degree, maybe I could go higher than suggested by the manual? Then I might get a denser print at faster exposures.
Second. I have read several times, that I should check on the installation of the lamp. I actually did that myself, but I never figured something could go wrong there, seems really simple. So what could be wrong?
thanks for all the replys! best regards Sam
Today I raised temperature of both blix and development to 37 instead of 33 degree... right now I am at 25s. with f4 and a half. Still not like it should be though...
What does temperature does?
And maybe someone could lay down what to watch out for when checking on the lamp.
I think I might found the issue...
I opened up the enlarger and the lamp was floating loose in the cabin!?
It needs to be secured with two screwes, but it wasn't - guess I have not been really carefull when installing the lamp.
Small problem is that I can't find the screwes anymore... guess I am screwed ....
in the end I'll fix it, and i'll keep this thread updated for whoever it might help.
in the mean while the whole temperature thing got me interested.
I know how to manipulate color, but what are the effects of both development time and temperature? Are they common parameters in manipulating the final print?
I use developer temperatures from 68 deg F (~20 deg C) to 100 deg F (~38 deg C). The time is 2' at 68 deg and 1' at 100 deg. The print shifts on the yellow - blue axis over that range of time/temp., with about the same density overall.
Blix time is about 2'30" at 68 deg and 1' at 100 deg and I use a wash of about 10' at 68 deg F and about 2'30" at 100 deg. I know this is not the 'real' times, but I have clocked blix and wash action on this paper a lot and it works well.
I can only set my developement time... no blix time
is that weird?