Soft Prints -- Diffraction?

Discussion in 'Enlarging' started by tsoved, Apr 14, 2012.

  1. tsoved

    tsoved Member

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    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?
     
  2. Nicholas Lindan

    Nicholas Lindan Advertiser

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    I wouldn't put much faith in a grain focuser as a judge of diffraction.

    What do prints made at f8 look like?
     
  3. RalphLambrecht

    RalphLambrecht Subscriber

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    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.
     
  4. tsoved

    tsoved Member

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    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...
     
  5. Ian C

    Ian C Member

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    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.
     
  6. tsoved

    tsoved Member

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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.
     
  7. bsdunek

    bsdunek Subscriber

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    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!
     
  8. Ian C

    Ian C Member

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    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.
     
  9. tkamiya

    tkamiya Member

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    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.
     
  10. tsoved

    tsoved Member

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    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...
     
  11. Ian C

    Ian C Member

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    If you use the black paper mask to space the negative from the top glass, then Newton rings ought not to form in the first place. They occur when the smooth top surface of the negative is held tightly to the bottom surface of the top glass. The mask should provide a small amount of clearance and prevent the problem. The negative will be restrained within the depth of field about the negative's plane of focus to keep the projection crisp.
     
  12. Kevin Kehler

    Kevin Kehler Member

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    There is another issue which hasn't been addressed, namely that the negative might either be out of focus or diffraction within the image itself. While the grain is evident or prominent as you say, that is referring to the silver grain of the physical negative and not about the image on the negative. What was the f-stop of the image you took? If it was f16-f22 on a 35mm camera, no amount of darkroom manipulation will make it sharper than what is inherent in the negative itself. The focus enlarger can tell you want the maximum sharpness of the negative is, not what the sharpness of the image is.
     
  13. tkamiya

    tkamiya Member

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    My enlarger do this....

    Is it possible that your focus is shifting because your enlarger head is creeping down or bellows is creeping down?

    Check your focus before and after the exposure and compare.... is it shifting?
     
  14. tsoved

    tsoved Member

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    Ian -- I am definitely going to give the glass carrier a try. Also, thank you very much for the explanation of DOF and enlarger alignment. It was an excellent explanation and very enlightening!

    Kevin -- The problem I am having is that when I focus the projection at f/2.8, the grain is sharp. When I print stopped down,though, the grain is not even visible in the print. I have printed from these negatives in the past on different equipment with pleasing results, so, in this case, fortunately, the negatives are fine.

    tkamiya -- I had initially ruled this possibility out simply because it's such a struggle to get the enlarger head to move at all (it could use a good greasing, I think), but I will definitely take your suggestion and check.
     
  15. Rick A

    Rick A Subscriber

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    If you have sharp looking grain at 2.8 then it becomes diffuse at smaller f/stops I would suspect the lens has issues. You are describing an issue I have never seen even with cheap lenses. I own two new version El-Nikor 50/2.8 lenses and both remain tack sharp throughout the entire range of settings.
     
  16. pentaxuser

    pentaxuser Subscriber

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    Let's hope you have got a good lens and maybe lenses are much cheaper in the U.S. but I wouldn't sell my El Nikkor 2.8 for $20 unless I was in debt to the Mafia and the Goodfellas were surrounding me and had taken a liking to it :D. These lenses never sell for anything like that price in the U.K. More like $60 and even then a bargain

    Might be worth getting an expert to look at it

    pentaxuser
     
  17. cliveh

    cliveh Subscriber

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    As your original post states - soft prints, I would suggest the solution to your problem is the exposure and development of your negatives. Get that right and the rest is easy.
     
  18. tsoved

    tsoved Member

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    Rick -- The lens has been in storage for a few months and may not have fared well as it was moved from closet to closet, but I'm pretty sure it was working well the last time I used it (November, I think). Previously, I had been using the newer version of the EL Nikkor 50mm f/2.8, and I loved it. Are there any optical differences between them? Or does the newer one just have a fancier looking barrel?

    Pentaxuser -- I may finance my next trip to the UK by smuggling a bag full of them, then! Unless someone on here can correct me, central Arkansas has a dearth of analog photography supplies and services (except for the fellow in Sherwood that sells Weincell batteries and Super 8 film), so I may be hard pressed to find an expert to look it over...
     
  19. tsoved

    tsoved Member

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    cliveh -- I know firsthand the woes of lousy negatives. But the reason that I am perplexed by these prints is because I've printed from these very negatives before on other equipment with excellent results (my pictures themselves may not be great, but the prints were razor sharp and exposed to my liking).
     
  20. cliveh

    cliveh Subscriber

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    Take the enlarger apart, as you may have a shot away filtration system or bits blocking the light path.
     
  21. tsoved

    tsoved Member

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    Having cast them aside in disgust, I've finally mustered the courage to look back over the prints, and I'm thinking now that it probably is an issue with film flatness. So, I'm going to give Ian's DIY glass negative carrier a try -- though it will probably be a week or so before I get the chance.

    Thank you all very much for your helpful tips and suggestions!
     
  22. John Wiegerink

    John Wiegerink Member

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    Much good advice and some hints. If your negative is "popping" in the carrier it is best to make sure your are doing everything while it's popped from the heat. Of course keeping it flat is the best way and glass will do that. Some of us old slide projector people used to let the slide "pop" from heat before we would focus the projector. If you focused first the slide would just heat and pop out of focus. Your negatives could be doing the same think. Check the grain when first turned on and then a few minutes later. if you have a "popping" problem you'll know it. You also have to remember that your grain focuser in magnified at least 10X to 15X and you'll see grain with that and not in a normal size print. 16x20 from 35mm yes you'll see grain. 16x20 from 120 maybe not. Also, once you have things in-focus use your enlarger locks for the column if there is any. Your equipment is first rate and should not be the issue. I said "should not"! JohnW
     
  23. tkamiya

    tkamiya Member

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    Something is awfully wrong. B22 may not be the toughest enlarger ever made but it is a workhorse machine. I really doubt it's THAT unstable to cause blurry image by shaking that much.

    I am suspecting your lens is sick.

    Enlarger is just a machine to house lamp, condenser, and to keep light inside. I doubt your flim is popping because there is a condenser between lamp and the negs. If the alignment is off, you'd see sharp portion somewhere on your print. You indicated your problem is uniform. Dirty condenser isn't going to cause the problem you describe either as it is above your negs. It won't affect sharpness like you describe. Your likely problem is between your negative and the paper - which leaves lens.

    If you want to try your setup with a new lens, I have a lens I can send to you. It's not a great lens but it'll be sufficient to check and make sure rest of your setup is fine. PM me with your address if you want to do this. You only pay for shipping from Florida.
     
  24. ic-racer

    ic-racer Member

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    Yes, diffraction starts the moment you stop down, but you need to take into account the lower contrast, less flat field, smaller image circle and increased aberration when using the lens wide open. The usual recommendation to stop down two or 3 stops provides the best compromise in most situations. Simple advice, well tested and proven.
     
  25. kevs

    kevs Member

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    tsoved,

    Is the light path in your enlarger clean? Lamps, condensers, filters and diffusers can accumulate dust is storage, and stopping down increses the depth of field so that what you don't notice on focussing at f2.8 could easily affect the print at f8. So you could easily have a film of muck on surfaces you wouldn't even notice. I'm not saying that's a definitve cause, but it won't hurt to check it out.

    Good luck and cheers,,
    kevs.