Soft Prints -- Diffraction?
I set up my makeshift home darkroom for the first time last night, and, so far, I'm bitterly disappointed. The enlarger is pretty lightweight and certainly lacking in other areas as well, so the problem could just be vibrations. It's a dreadful Omega B22. The lens is an EL Nikkor 50mm f/2.8 which I think I've had pleasing results from in the past on other enlargers.
However, looking through my grain focuser, I notice what I assume to be diffraction becoming obvious two stops down and becoming downright hideous stopped all the way down.
So, I try to print at f/2.8 or f/4, but I don't have any filters, so my exposure times are 2-5 seconds. Thus far, the pursuit is a grand waste of paper. Please advise. Should I put the enlarger in the recycle bin with the soda cans and cardboard boxes? Should I spend all the money I don't have on a better enlarger and a Rodenstock or Schneider lens?
I wouldn't put much faith in a grain focuser as a judge of diffraction.
What do prints made at f8 look like?
your lens is one of the best,no need to replace it!try to print at it's 'sweet' spot around f/8-11,and try to fix the top of your enlarger olumn to the wall to eliminate vibration and you'll be ine.
Nicholas -- Last night's prints at f/8 were hideous. It has been a long time, but I'm sure I've had good results at f/8 in the past with this lens on other enlargers, so I suppose that does rule out diffraction. I shot Tri-X and stand developed for an hour in 1+100 Rodinal, so the grain is very apparent. My concern over what I saw through the grain focuser came because at f/2.8 and f/4 the grain had sharp edges, but the farther I stopped down, the softer its edges became and the blobbier it looked. I suppose this could just be because it was darker and I couldn't see as well.
Ralph -- Thanks for boosting my confidence in the lens! I did choose it for the glowing reviews I've read of it, and, though it's been a while since I used it last, I'm sure it was giving excellent results at f/8. As for fixing the enlarger column to the wall -- well, I'm not sure how my mom will feel about that...
You currently own one of the finest enlarging lenses made. Diffraction is caused by light that’s distorted by grazing the edge of the aperture blades. That’s the same in all lenses. Diffraction isn’t caused by the glass. The 50/2.8 EL Nikkor has the best combination of resolution and preservation of contrast closed 2 stops at f/5.6. It also works well at f/4 to at least f/8. The further you close the aperture, the higher the percentage of diffracted image-forming light. This is true of all lenses.
If your prints are truly soft, then you have to start looking for the actual cause. The Omega B22 is as good or as bad as your abilities to set it up properly. I’ve seen exceptional prints made on simple enlargers like the Omega B22 and some truly hideous ones made on very expensive Durst enlargers. Print quality is due to the skill of the user and his or her ability to analyze problems and correct them.
The biggest problem is keeping the negative flat during the exposure. The root cause of unsharpness in enlarging is often the warming of the negative as it absorbs heat from the light passing through it. That makes it belly up and out of the shallow depth of field during the exposure.
We combat this with a heat-absorbing glass filter well above the negative, a glass sandwich negative carrier, or both. If your B-22 isn’t equipped with either the 473-101 or the 473-113 heat-absorbing glass filters (assuming that it’s equipped with the common condenser lamphouse), then keeping the negative cool and flat in a standard carrier is impossible.
If you make a 8.5”-wide projection of a 35mm negative with a 50mm lens at f/5.6, the DOF about the plane of focus for the negative is about 0.35mm or 0.014”. If the negative moves more than half of that distance in warming, the projection will begin to degrade.
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Ian -- I'm glad again to hear the lens praised so highly. I feel like I really lucked out getting it for $20 on eBay (though I see that many are listed right now for little more than that).
Surely the problem I am experiencing is due to lack of proper setup as you suggest. Unfortunately, there is nowhere in my home that I can work besides one tiny little hallway that is literally only six inches wider than the baseboard of the enlarger. And, aside from the floor, there is nothing to put the enlarger on besides a rolling butcher's block borrowed from the kitchen. The wheels lock, and it is quite heavy, but it probably does contribute greatly to the vibrations.
I do not have a glass negative carrier, and I doubt that the enlarger has the heat-absorbing glass filter you mention. The lamp in my Omega B22 may burn hotter than the lamps in the 23Cs and the Omega color enlarger I've used in the past, because I've never had such soft prints. It was very disheartening, and I may or may not have cried myself to sleep over the prints I made last night.
My Dad used a B-22 for years and made very sharp 16 X 20 prints when needed. The advice above is good. Adding to that is, is your condenser pack correct? That can also have an effect, especially at the edges. Dad's enlarger is packed away in the attic or I would take a look to see how it's set up. In this case, don't blame the equipment - you have good stuff!
I don’t think that Omega made a glass carrier for the B22. But there’s no reason you can’t make a simple one yourself from two identical pieces of window glass. I have done so when that was the only practical solution to a negative that I couldn’t keep cool and flat enough to project sharply. The sharp edges of the glass must be deburred with a fine whetstone so that the negative won’t be scratched. Then the sides have to be painted black to prevent light spill. I’d also use a single edge razor blade to cut a window mask out of black construction paper.
You’d center the negative over the lower glass, place the mask over the top of the negative to both mask it and to space the top of the negative away from the top glass by the thickness of the paper to prevent Newton rings. Put the top glass on and carefully place the sandwich into the enlarger.
This “poor man’s glass carrier” isn’t the fastest way to work, but it will keep the negative flat. Once you’ve refined the focus, the projection shouldn’t change as you make the exposure. In this way your B-22 should be capable of making a projection identical to one from any other enlarger using the same negative and lens. In the meanwhile, I'd look for the HA glass on eBay or ask in the Classifieds here.
You’re right. The dichoric color heads run much cooler than condenser heads. To the best of my knowledge, they’re all equipped with combination IR/UV filters, usually mounted onto the side of the mixing chamber in an Omega enlarger. I believe that the Omega Dichro B lamphouse can be fitted to the B22.
The vibration issue (assuming a wood floor) shouldn’t be a problem if you hold still before and during the exposure. It also helps to keep the timer off of the enlarger table so that triggering the timer doesn't cause vibrations. If your building is along side a busy road with heavy traffic, especially truck traffic, it might be a problem. Waiting until a time when traffic is minimum can help in that case.
A couple of thoughts:
While Nikkor 50mm f/2.8 is one of the better lenses and I use it myself (and very impressed by it), there is no guarantee that the one you have is undamaged. These days, we buy our equipment second hand and it is entirely possible someone may have took it apart to clean or otherwise caused some kind of damage. So I won't rule that out that your lens is bad. You might want to take it off your enlarger and inspect carefully for signs of neglect, damage, or contamination.
With that said...
I have no problem with my lens at f/4 to f/11. I have not tried outside of that range.
When I used "light weight" enlargers, I put my enlarger on a desk and I hang my timer on the wall so vibration from pushing the button does not transmit to the column. You might want to try it. Also.... is the sharpness of your image, the same all across your print? If not, your enlarger could be awfully out of alignment.
Develop, stop, fix.... wait.... where's my film?
Bruce -- I am also glad to hear that the ol' B22 can be used to good effect! I bought it along with a timer, a bunch of trays, and a negative carrier for $20 from the school I used to attend. It hadn't been used since the early 90s, apparently, and had the dust inside and out to prove it, so I could very well have repacked the condenser improperly. Thanks for the suggestion. I will do some research on that.
Ian -- I will definitely give the glass carrier a try. Do you think that Newtonian rings will be an issue? I had thought about this in the past but assumed I needed expensive AN glass that I wasn't willing to spend the money for.
Fortunately, I do not live on a busy street, but the wooden floors (especially in my little hallway) are quite wavy and spongy. I will try holding the timer. It's the finicky result of an old Heath kit, though, and inexplicably, the timer function doesn't work unless it is perfectly level! I really ought to get a more respectable one.
tkamiya -- The lens surely does have an interesting life story as it is the older version, and the fellow I bought it from was not the original owner. So, it could very well have suffered at the hands of an unskilled surgeon. I try to be mindful of enlarger alignment because I had the misfortune of learning on and using a terribly misaligned enlarger at school for about a year. When the opportunity came to use an enlarger that had been much better taken care of, the results were so drastically improved that I threw out most of my old prints. The old ones were so lacking in sharpness by comparison. This enlarger I have now seems well aligned. At f/2.8, looking through the grain enlarger, the corners of the image appear just as sharply as the center. And my prints from last night are uniformly awful...