How long is too long of print exposure?

[C-130 Nav]

I ran into a tricky print yesterday in my darkroom. It took significantly longer to expose the print and the results were lackluster. I print on an Omega D-II with a PH211 75W bulb, use Ilford Multigrade RC paper, and use f/11 (the highest resolution setting on my 50mm and 100mm lenses). Print sizes are usually 8x10 or less from a 35mm negative.

Without using an Ilford contrast filter, my print times are between 12 and 20 seconds, depending on enlargement, density, etc. If I add in a filter (00-3 1/2 grade), I'll see my print times rise to 35-50 seconds or so. Filter grades 4+ usually are in the 70+ second range.

Yesterday, I couldn't get a decent print on a snow scene with a 50mm lens, f/11 and a no. 3 filter at anything less than 150 seconds. I opened up the stop to f/8 and a 70 second exposure was close but not quite right. I noticed lots of unequally distributed gray spots forming in the highlight areas of the print.

I'd prefer not to 1) go lower than f/8 on the lens f-stop (flare and corner sharpness) or 2) use a PH212 150W bulb (gets hot). I am using the D-II's 4.5 inch condenser (designed for medium negatives) in the enlarger instead of the 3 inch condenser (for miniature negatives). I do this for ease of setup and to maintain same relative variables when printing either 120 or 135 films.

My questions are:
1) What maximum exposure is reasonable before other factors start affecting print quality to a noticeable extent?
2) What problems or negative effects can I expect to see with too long of an exposure?
3) Any tips, tricks or considerations to manage exposure times for this setup?

 

[MattKing]

70 seconds is short. You need to get into much longer exposures before any reciprocity issues arise.
Longer exposures mean:
1) low productivity;
2) higher vulnerability to introducing vibration; and
3) inconvenience,
so I try to avoid them, but by themselves they don't introduce print degradation.
If you see added mottling, check to see if you have any light leaking from the enlarger that is affecting your prints. If so, longer print times could increase the degradation arising from that.

 

[ic-racer]

use f/11 (the highest resolution setting on my 50mm

The f11 results are not even shown by Schneider since they are degraded by diffraction. Why not use f8 or f5.6?

 

[Andrew O'Neill]

The longest "base" exposure I've done was around a minute. I'm pretty anal about keeping my aperture two stops down, as that is its sharpest there. My exposures are done in three second blasts. I find this a more precise way to do dodging and burning.

 

[C-130 Nav]

Thanks all for the comments. I use Kodak Ektar enlarging lenses. I read a Kodak data book that listed the resolution for these lenses at each f-stop with f/11 being sharpest. Unfortunately, now I can't find that reference - so if anyone out there knows, it'd be a help. The other Kodak reference books that I do have and checked indicate diffraction at f/16 and smaller apertures with recommendations to use them at f/11 and f/8. The lenses also have f/5.6 and f/4.5 stops but I think I should stay away from those. I've noticed significant flare in the f/4.5 range.

 

[cliveh]

Well if I'm printing a 10" X 8" black & white print onto multigrade paper, from a 35mm negative on a Durst condenser enlarger, then 95% of my prints are made at two or three stops down with no contrast, no dodging or burning, at between 6 and 12 seconds. If any longer, then I know I have a problem.

 

[Jim Jones]

C-130 Nav -- I'm surprised that f/11 is your sharpest aperture on your enlarging lenses. Some enlargers, even from respectable makers, come with modest lenses. The several El-Nikkor 50nn f/2.8 lenses I used over many years were consistently sharpest at f/4 and f/5.6. The grain of fine-grain film was noticeably less sharp at f/8, and I never used f/11. Using the correct condensing lenses for each format may cure other parts of your problems.

 

[MattKing]

Thanks all for the comments. I use Kodak Ektar enlarging lenses. I read a Kodak data book that listed the resolution for these lenses at each f-stop with f/11 being sharpest. Unfortunately, now I can't find that reference - so if anyone out there knows, it'd be a help. The other Kodak reference books that I do have and checked indicate diffraction at f/16 and smaller apertures with recommendations to use them at f/11 and f/8. The lenses also have f/5.6 and f/4.5 stops but I think I should stay away from those. I've noticed significant flare in the f/4.5 range.

FWIW, at print sizes of 8"x10" from 35mm, I'm not sure you will be able to see diffraction effects if you are an aperture stop or two away from optimum. Perhaps a high degree of magnification of the print might make them visible.
I tried looking up my Kodak references, but they don't include resolution figures for the Kodak enlarging lenses. They do say though that diffraction effects will be of relatively little concern at any aperture available.

 

[Vaughn]

Long exposures under the enlarger will require a little more care to prevent fogging from the enlarger itself or due to the increased time under perhaps not-quite-so-safe safelights.

A good way to kill those highlights.

 

[Nicholas Lindan]

The other drawback to long exposures is the increased effect of stray light leaking from the enlarger. My Omega D3 leaked a lot of light from the negative carrier area and I remember draping black cloth around that area when I needed long exposure times.

To look for possible stray light put a cap on the lens, turn on the enlarger and see how much light is hitting the easel. A mirror on the easel can let you get a 'paper's eye' perspective on any stray light and let you see where it is coming from (easier than trying to peer up from the easel).

 

[C-130 Nav]

Thanks for the tips. I did a safelight check a while ago and they appear to be good for at least 6 minutes with no effect on the paper (my darkroom is pretty dim with only two 25W bulbs in safelights on an 8 ft ceiling). Also, knowing the D-II leaks light, I’ve used 3M no. 235 photography tape to block all the light leaks I could find. The place I still get leaks is around the condenser-negative carrier interface and I wrap that location with a strip of cloth. There’s always a possibility I missed a spot so I won’t say it’s perfect.

I appreciate the mirror trick mentioned by Nicholas - I hadn’t thought of that or tried that yet. I may find something stray.

I just bought an older lamp head for my D-II (this one doesn’t have the filter opening/door which leaks a lot of light). When I swap heads, I’ll try the 3 inch condenser for 50mm lenses. I’ll also give f/8 and f/5.6 a test and see if that helps with grain sharpness.

 

[Ko.Fe.]

Some of my ECN-2 developed in BW negatives needs two minutes exposures. No problems noticed.

 

[Doremus Scudder]

If your base exposures are consistently longer than 30+ seconds for "normal-size" enlargements, I'd be looking for something wrong; light source, condensers, etc.

That said, your only real enemy for exposures up to several minutes long is stray light, either from the enlarger or from unsafe safelights. When I have a really long print exposure, I'll turn off the safelights closest to the enlarger. And, like Nicholas, I've checked my enlarger for leaks and baffled and blocked where necessary.

FWIW, I time exposures with the metronome function on my timer, just counting in my head, so the timer is set permanently on 99 seconds. Quite often I have to hit the footswitch for another 99 seconds once or twice for prints, especially when the burning is a bit complicated. I don't worry about 3-5 minutes total exposure time if it's needed.

Best,

Doremus

 

[MattKing]

If your base exposures are consistently longer than 30+ seconds for "normal-size" enlargements, I'd be looking for something wrong; light source, condensers, etc.

As an example, the LPL 7700 enlargers with VCCE or colour heads don't offer a specialized light diffuser for smaller formats, so 35mm print times can be comparatively quite long compared to other enlargers that I have worked with.
But the prints from 35mm are still excellent, if the negative is good, and the operator does what he (me) is supposed to do.

 

[R.Gould]

No time is to long, I always wind my enlarger lens aperture all the way down, to give me as lon a time as possible, gives me more time for dodging and burning, and with the longer times a second or so doesn't make such a huge difference to the finished, I got this from attending a weekend course with Robin Bell, probably the best printer around today, he has and still does make prints for many of the greats of photography, and always goes for these long times, I used to worry about using long times, never closing the lens more than 8 or 11, sharpness Ect, but after attending this course I stopped worrying and just went for the longer times, sometimes with a base exposure of 60 0r 70 seconds, if it is good enough for Robin Bell it is good enough for me

 

[brian steinberger]

I’m in the two stops down camp. That’s where my lenses shine. I then use ND filters to lengthen my exposure times. For me they’re never longer than 12-20seconds. If I didn’t use ND they would be 8 seconds or less. I find papers keep getting faster!

 

[Zathras]

I think that you're using the wrong condenser for the 50mm lens. It sounds like you have the same enlarger as I do, and
you definitely have to match the condenser to your lens. The old D-ll units did not come with the variable condenser head
that the later D-2 had. You can use the wrong condensers with the 50mm lens, but the projected image is less bright. This
makes longer base exposures necessary, which can then lead to paper fogging if you have any light leaks. I installed a
variable condenser head on my D-II a couple of years ago, and it's a lot more convenient than changing the condensers out
all the time. If you have the big condensers for 4x5 negs, all you need to get is the variable condenser box that goes in
between the condenser and the lamp holder, the variable condenser lens and you're in business. If you don't have the
variable condenser unit, just make sure that you have the correct condenser installed for lens you're using.

Don't forget to look for and eliminate any light leaks from your enlarger too. By the way, I also use the Kodak Enlarging
Ektar lenses on my D-II. They're great lenses.

 

[cliveh]

The f11 results are not even shown by Schneider since they are degraded by diffraction. Why not use f8 or f5.6?
View attachment 266596

This is about as useful as a chocolate teapot.

 

[DREW WILEY]

Too long is when you find a spider web woven over the lens, or over your body waiting around. Just kidding. Most of the time my problem is exposures that are too fast. I once had one of those 50mm Componon S lenses; it was OK, just OK. I'd rather use a significantly longer lens wide open, using just the center of the optic. That's what I did to enlarge directly onto slow Azo paper with a basic Omega system. That's just about the only application where the time went over a minute. But unless someone is using a tight glass carrier, with everything else aligned, this whole discussion is a waste of time, because your film plane isn't flat or stable to begin with.

 

[John O]

When I use Ilford MG paper in my pinhole camera the exposure time is sometimes up to 30 minutes. If there's enough light for my exposure meter, I seem to get want I want without worrying about reciprocity.