Newbie question #2
I noticed that when I enlarge a 35mm negative to 11x14 using a Beseler 23CII enlarger and a Nikkor 50mm enlarging lens at the widest aperture (2.8), the corners of the print seem underexposed. The height of the enlarger head is set to the 35mm level.
Is this a problem with using the enlarger lens at the widest aperture and if so, how much should I step down to avoid this problem. At 2.8, the print requires about 30 seconds. Stepping down would thus increase the exposure time to 1 or more minutes. Since I am new to printing, is 1-2 or more minutes considered typical and am I being too impatient in trying to reduce the exposure times by keeping the lens wide open?
You're encountering vignetting. This can be caused by the lens, the condensers, or various other things. My own Nikon EL-Nikkor f/2.8 lens doesn't seem to vignette much, but I also seldom print at f/2.8. My own times are usually in the 10-40s range for an 8x10 print at f/5.6 or f/8. An 11x14 would require about twice that, or open up by one stop. My enlarger is a Philips PCS130 with PCS150 color controller.
Thus, I've got a few suggestions:
- Examine your lens for signs of damage -- dirty elements or fungus, say.
- Examine your condensers in the same way.
- Verify that you've got the right condensers in place, and that they're positioned correctly. Condenser enlargers typically require either swapping condensers or shifting their positions for different film formats, and if you've got yours set up wrong, you could get vignetting.
- Check your bulb. You might have a bulb that's dim from clouding or that's of too low a wattage. Changing the bulb might not affect your vignetting problem, but it might shorten your printing times. Don't use a bulb of a higher wattage than the manufacturer recommends, though.
Make sure the poly-contrast filter holder beneath the lens isn't blocking the corners, too.
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And as to time adjustments, the Law of Reciprocity apllies to enlarging as well as capture.
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Long exposure time should not affect quality. The only thing is to avoid vibrations, no excessive movement in the dark room, no shock to table, etc.
I understand the density of your negative is quite high.
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Thank you for all of your responses. The Beseller 23C III as I am using it, is a dichro head, (not using it with its condenser head attachment) so I can just dial in the contrast I desire. I didn't install the condensers (is this correct?). The lens is new and free of fungus as is the bulb (new) which is an 85W halogen type.
In terms of vignetting, does it happen with wide open apertures? Would I avoid this problem stepping down a few f stops? I have a 105mm that I use for my 6x6 enlargement. Would using this lens change things? My 35mm negative is an outdoor sports scene of my son in a lacrosse game on a sunny day with trees in the background and turf in the foreground. Paper used Ilford MG FB glossy. Does 30 seconds sound too long for an adequate exposure for a 11x14 enlargement at 2.8?
Forgive my basic questions, as I picked this up late in life (never took high school photo), just doing it on my own.
I'm not familiar with the Beseler 23C series myself. My earlier comment about condensers was based on a quick Google that turned up a Craigs' List ad for one that was a condenser. It sounds like yours probably doesn't use the condensers, but you should check your manual (if you've got one) or take the advice of somebody who's more familiar with this model.
Originally Posted by Lawrence Chai
Again, check the manual, if you've got one. I see a lot of comments about ~150W bulbs for many popular enlargers, so it could be your 85W bulb is too dim. (My own enlarger takes three 35W bulbs, but it's a weird one.)
The lens is new and free of fungus as is the bulb (new) which is an 85W halogen type.
That might help -- but as you say, you've got rather long exposure times to start with, so unless/until you improve the brightness out of the enlarger, stopping down may be an awkward solution.
In terms of vignetting, does it happen with wide open apertures? Would I avoid this problem stepping down a few f stops?
I'd expect that would depend on whether the problem is primarily with the diffusion (or condenser) light source or with the lens. You could certainly try it; that might be a useful diagnostic test. Be aware that you'll need to raise the head higher to get an equivalent-sized print when you switch to a longer lens. Since you're talking about an 11x14 print, this will mean a pretty high head height -- perhaps higher than the enlarger supports. Most enlargers let you tilt the head for wall projection or reverse the head to project on the floor for situations like this.
I have a 105mm that I use for my 6x6 enlargement. Would using this lens change things?
There are so many variables from my own equipment and materials that I can't give you a definitive answer. Certainly I wouldn't get many 30-second exposures at f/2.8 to make an 11x14 with my equipment and materials. 30 seconds at f/5.6, perhaps, but not at f/2.8.
Paper used Ilford MG FB glossy. Does 30 seconds sound too long for an adequate exposure for a 11x14 enlargement at 2.8?
You refer to the bulb as being an 85 Watt halogen bulb. I think you may mean an 85 Volt halogen bulb, because my Beseler colour head (for a different enlarger - a Beseler 67 series) happens to use a halogen bulb with that rating.
Over the years, Beseler has made a number of different colour heads that have different power supply and bulb requirements. You may have something that is mismatched, or there may be a problem with the power supply for the head, or the dichroic filters may be sticking - there are a few possibilities.
In my case, my enlarger often produces too bright a light - my exposure times can be inconveniently short.
Do you have pix of the head and the power supply, or at least model numbers?
I run into the same problem when I print negatives exposed with ultra-wide lenses. It's called light-fall-off. It's also easy to correct for when printing the negative by burning in the corners of the print during the exposure. Cut a small disk out of some card stock about 2 or 3 inches in diameter, attach a length of stiff wire to it, then block the exposure in the center part of the projected image and give the corners some extra exposure (10-20%). Move the disk slowly up and down in the light path and allow more exposure in the corners. Do this as a second step after you've made your initial exposure. When you find the correct time ratio for the two exposures your prints will be exposed correctly from corner-to-corner. Ansel Adams often gave his prints a little extra exposure around the edges.
You can keep working and save paper by doing this while you investigate the issue.