It's a question of sharpness

Discussion in 'Enlarging' started by noblebeast, Feb 27, 2004.

  1. noblebeast

    noblebeast Member

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    This will be a somewhat windy explanation with a couple of questions at the end. I have been having problems with edge to edge sharpness in my prints and after following the good advice in other threads regarding enlarger alignment, I brought my Beseler 23C up to code, so to speak. But I still can't get the negatives focused all the way around: the center will be sharp but the left side will be slightly out of focus and the right side a bit more. I did battle with it tonight for about two hours using a bit of film leader with a grid scratched into it, and no amount of adjusting will get all quadrants into focus - the center still gets very sharp, but even when I get the edges close they still don't get as sharp as the center. I've tried shifting the lensboard to see if the soft areas change, but they stay constant. Again, I've already checked to make sure the different planes are parallel.

    I use 35mm and 6X4.5 and 6X6 formats, and have verified that the negatives I have been trying to print are indeed sharp from edge to edge.

    So I've come up with two possible solutions I wanted to get advice on, and please feel free to offer more. Number 1: my lenses are probably entry-level, hobbyist quality. Would higher quality enlarger optics make a substantial, easy to see difference in the edge to edge sharpness? Number 2: I'm using the basic negative holders. Would glass holders (assuming they make them for the 23C) make a noticeable difference by virtue of the fact that they hold the negatives flatter?

    Thanks in advance.
     
  2. clogz

    clogz Subscriber

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    Yes, I prefer using glass neg. carriers esp for MF negatives. Make sure though that the top one is of the anti-newton variety.
     
  3. victor

    victor Member

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    nabblbeast, if u use condensor head, than problems is more pronounced. the reason is that very quekly the negative is hot from the light sourse and it changes the form. so what u do is that u focus on the centere which is not on the same plane as other parts. anti-newton helps very much, but be aware of dust etc. u have to be even cleaner than befor.
    align the enlarger of course. and yes, better lenses helps. but only when u have made the besic things -alighned enlarger and flat negative.
    also, if u print with the filters, wether the normal head(deffused) or with the condensor or the cold (with filters), make sure to change filters very gently, and wait abit, couse the vibration makes problems.
     
  4. dr bob

    dr bob Member

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    As previously stated, negative "pop" is a possible problem which will be corrected by using glass carriers. Have you tried stopping down to the maximum to compare prints? A smaller diaphragm (exception being a point source head) should minimize focus (sharpness) problems stated.

    Personally, (dangerous territory, I know) I found my enlarging problems dissipated greatly when I first invested in a "good" lens to replace the "entry-level, hobbyist quality" ones which came standard on my first enlarger - including overall sharpness. BTW, if you are doing b&w, the super modern, highly corrected $$$ lenses are not really required.
     
  5. Ed Sukach

    Ed Sukach Member

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    It sounds like the lens itself. What aperture are you using? I usually focus wide open to minimize depth of focus, and print closed down to use the benefit of depth of focus. Try an aperture near the middle of the scale.
    An additional consideration is the ratio of enlargement. Inexpensive lenses are designed to work best at relative small ratios with the idea that beginners will not need LARGE prints. The effects of field curvature (which your descripption sounds like) are more noticeable at higher ratios.

    Will the use of a "high quality lens" make a substantial difference? At high magnification ratios, it is likely. Will it be immediately discernable? Nearly impossible to answer .. It depends on the subject, the print size, viewing distance, whether or not smoking is allowed in the gallery, level of alcohol consumption....

    Be careful of one optical characteristic - color correction. It is as necessary for sharpness (resolution) in black and white images as it is with those printed in color. Different wavelengths of light (colors) should, ideally, focus to the same place; if they do not, there will be a "rainbow" effect at the image edges - usually most noticeable at the extremes of the field. The color *fidelity* - the accurate rendering of colors, is a different animal.
     
  6. MikeK

    MikeK Member

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    Couple more thoughts on this problem, and I assume it is the condensor variety.

    The condenser setting needs to be changed for the different negative sizes. The condenser head needs to be move up from the negative stage when using 35mm and moved closer to the negative stage when using larger formats. You should have an adjustment bar on the right hand side of the enlarger.

    Next are you using the same lens for all your formats. A lens that covers 35mm will not give good coverage with a 6x6 negative, you should ideally be using something like this:

    35mm negative = 50mm enlarging lend
    6x4.5mm negative = 75mm - 80mm enlarging lens
    6x6cm = 80mm enlarging lens

    You could of course use an 80mm enlarging lens for all formats but you will be limited wth the magnification you can get when you use an 80mm lens with a 35mm negative.

    I would check these out first before purchasing a new lens.

    - Mike
     
  7. ann

    ann Subscriber

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    it would appear others have covered the most common problems. Have you check the baseboard to be sure it is level? We had a board that looked flat, etc. but when we continued to have trouble with sharpness i got out the leveler and started checking. it was not flat, very little but never the less not flat. Just another option in the puzzle.
     
  8. Les McLean

    Les McLean Subscriber

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    I experienced the same problems a few years ago and I was using good enlarging lens on a Zone VI VC Cold Cathode enlarger and thought that I had my enlarger correctly aligned. I tried every remedy mentioned here but it was not until I invested in a quality lens alignment system, the Versilab Laser tool, that I cured the problem.

    It takes less than 2 minutes to check the alignment and it is sharp from corner to corner every time. I have also noticed that the alignment can shift as the head is moved up and down the column so for that reason I check the alignment for every print that I make if I have moved the head on the column. The initial investment for the tool may seem to be high but in my view if you are looking for the best results you should be prepared to spend the money, I believe there is no other way.
     
  9. noblebeast

    noblebeast Member

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    Wow! First of all a Big THANK YOU for all of the quick and informed replies - that's what makes APUG the best place in the whole wide world!

    To answer some of the loose ends: Yes it is a condenser enlarger and yes I adjust the condensers for each film format.

    I have been getting the problem regardless of how far down I stop the lenses. I used to use the smallest aperture but then read that diffraction can occur at the smallest lens opening on the enlarger as well as the camera so last night I tried stopping down to the middle stops - still no edge sharpness (fuzziness no better, but no worse).

    I use a 50mm lens for 35mm and a 75mm for medium formats. Again, the quality of these particular lenses is very suspect - for example the 50mm only has four, count 'm 4, aperture blades! I have only been enlarging to 8X10, printing the negs as full frame as the different ratios will allow.

    Les seems to have the ultimate alignment solution, but since, to partially quote Paul Simon, "I am just a poor boy..." (and in fact I was once a boxer), I am leaning towards better enlarger optics since they won't really go to waste anyway. Based on the responses thus far that seems like the next step.

    Thanks again, you're all the best!

    Joe
     
  10. Ed Sukach

    Ed Sukach Member

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    I wouldn't hesitate to use the smallest f/stop because of the "risk of diffraction."
    Any lens designer worth half the powder to blow them to hell will know enough to limit the smallest lens opening available so that diffraction errors will not be a problem. Diffraction is independent of the glass itself: it is a result of the physical size of the lens opening and the distance of aperture to film plane.
    That is why short-focus lenses have smallest openings of f/16 and the long, large format lenses go to f/64 or ?

    Of course, it is possible to find a lens that is a total disaster.

    The more I think of it, the more inclined I am to agree with Les... It does sound like an alignment problem. Is there a uniform loss of sharpness around the periphery of the frame? If the image is sharp along a particular radial axis when the center of the image is in focus, the baseboard is not perpendicular to the optical axis of the lens.
     
  11. noblebeast

    noblebeast Member

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    Well, that's just it. The outer edges are out of focus/less sharp all the way around. When I do adjust things one side, for example the left side, will seem to get slightly sharper, but it doesn't translate all that well to the print, and of course doesn't help the right side out too much. I should note this particular adjustment is made using the side to side adjustment of the lens holder. The front to back adjustment (23C owners will know what I'm so poorly describing here) has absolutely no effect on the image sharpness. All this leads me to suspect crummy optics. I just obtained a Rodenstock 75mm from my camera repair guy and have mounted it on the enlarger and will try it tonight (I have to wait for dark to have a darkroom that will live up to its name). But even in the dimmed light in the room I can see a bit of difference when I project my home-scratched reference negative, especially when I stop down. Granted, it's not a Schneider APO, but it should let me know if I'm barking up the right tree or just chasing my tail.
     
  12. Donald Miller

    Donald Miller Member

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    I had a similar problem some years ago...ended up my easel wasn't level.
     
  13. Alex Hawley

    Alex Hawley Member

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    I wouldn't spend money on glass negative carriers yet. They really are not necessary unless you go up to 5x7 or 8x10. If the problem is negative pop, it can be alleviated by turning on the lamp and letting the negative warm up . Once in a while you will get a neg that seems finicky in this regard but it can still be exposed satisfactorily. I've only had one 4x5 negative that gives me this problem. It ahouldn't ever be a problem with 35mm.

    Make sure your condensor setting is right for the format. You can actually "focus" the condesor by turning on the lamp, no negative or negative carrier in place and "focus" the projected light on the baseboard by moving the condensor adjustment. Try it, you'll see how it works.
     
  14. blansky

    blansky Subscriber

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    Not to belittle you problem, but this could save you all that money on that Holga that you were planning to buy.

    Besides that, what's with all the sharpness fetish anyway. Sally Mann and others have headed back from that elitist F64 club started by Adams et all, and now is showing a lot of disdain for sharpness.

    Do we really need all that realism in the world today.

    Noblebeast, perhaps you are on to something and don't recognise it's benefits.

    Maybe you are a trendsetter and just didn't realize it.

    Maybe this is the "next big thing" and everyone will think you are a genius.

    So, go ahead align your enlarger, buy a sharp lens, and watch fame and fortune go swirling down the drain.



    Just a thought

    Michael McBlane
     
  15. mark

    mark Member

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    SOunds a lot like negative pop like some have suggested. The wonders of heat expansion. I never believed it until I saw it happen and set out on a mission to figure out what to do about it. The different levels of sharpness on the edges tells a lot.

    I am poor as well and was using darkroom time at the community college. The enlargers were the same as yours if I remember correctly. The looser a neg is held in the carrier the larger the pop. you have to tighten things up so the neg is really held tight with no room to shift. In my opinion if you can shift position of the neg when it is held in the enlarger things are too loose and negative pop will be bad.

    I removed the annoying spring that pops open the carrier a little when you take it out of the enlarger. This allowed the carrier to lie flat on top of the neg. Then I made sure the enlarger clamped tight as hell on the carrier. The condensor weight is what is holding the carrier in place but it was not aligned so it layed flat across the carrier. Higher in the back by a smidge. If I remember corectly this was solved with brute force.

    The problem was not totally solved but the smaller aperatures took care of the rest. To totally get rid of the problem you will need a glass carrier.

    Good luck, I do not think new lenses will solve the problem.
     
  16. erickson

    erickson Member

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    I have an older 23C II enlarger with condenser head and El-Nikkor 50mm f/2.8 lens. Sharpness isn't a problem for me with the lens wide open at f/2.8. If your 23C can't accomplish 35mm full-frame sharpness at *any* available aperture, the lens could be the culprit.

    Finally, I don't remember if you said that the lens was clean or not. There aren't any smudges or anything like that around the edges are there?
     
  17. noblebeast

    noblebeast Member

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    Thanks again for all the new replies.

    Negative pop is probably not an issue since I am taking sooooo long trying to get the damn things in total focus. But making sure said negative is clamped tightly in the holder makes sense - I will add that to my next experiment.

    Lenses and condensers and everything else I can find have been cleaned till they cry "Uncle!" After my initial tests with the new used Rodenstock, I believe the lenses are indeed the culprits. Word of advice: if your lens only has four aperture blades, you are probably not getting the finest German glass.

    Although now that I read Blansky's post, maybe this crappy focus thing is serendipity helping me to find my photographic voice as it were. I can see it now: fame, fortune and millions of my fuzzy photos hanging in optometrists offices all over the world. That'll be an amazing fifteen minutes! Then I can sell my wonderful fuzzy-focus enlarger lens to a Noblebeast wannabe for thousands of dollars on Ebay. Maybe I better hang on to this thing...
     
  18. Ed Sukach

    Ed Sukach Member

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    One of the most useful accessories I have in my darkroom are two "Softener" (that's all labeling they have) filters. I bought them on a whim from a "miscellaneous" used filter box for very little money - mainly because they were 40.5mm filters - just the right size to fit my Rodenstock enlarging lenses. They work *beautifully* in printing portraits.
    I now rarely use the Hasselbad "Softars". There is more flexibility in keeping the sharpness in the negative and softening the enlarging image as needed.
     
  19. jovo

    jovo Membership Council Council

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    Entry level lenses are usually 3 element affairs...by all means borrow a better one, try it out, and I'll bet your problem will disappear. I've never been disappointed with my El Nikkor lenses (a 50mm, a 105mm and a just obtained 150mm).

    The 35mm negatives are small enough that warping or popping in the carrier shouldn't be a factor. Glassless carriers work quite well. Look to the lens for a 'cure'.
     
  20. noblebeast

    noblebeast Member

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    I am officially declaring my sharpness issue an enlarger lens problem. The better lens made all the difference in the world. Not that the enlarger still couldn't use a proper alignment, and after noticing that my 8X10 Speedeasel had more waves in it than the North Sea during a storm (thanks Donald - hadn't thought to check it) I'll be getting something a bit flatter. All of the other advice was terrific too, and all are things to remain aware of in the future (I'm still mulling over Blansky's suggestion though).

    Forgive the redundancy, but APUG is the best of its kind! (Sean, we need a cheerleader emoticon)