I need a better 105

Discussion in 'Darkroom Equipment' started by dpurdy, Jun 2, 2008.

  1. dpurdy

    dpurdy Member

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    I have spent a few days trying to do some precise enlarging on my Beseler 45 MXT. I am enlarging onto film making duplicate negs. I have very carefully adjusted the enlarger to be square and varified the focus is the best it can be corner to corner wide open. However my images won't get as sharp on the edges as it is in the center.

    The projected grains in the center are very precise sharp grains but as I move to the outer portions of the image the grains begin to get misshapen and lose the precise etchy sharpness.

    I have found the same thing to be true regardless if I use a 105 Nikor (my preferred lens), an old style 80mm Nikor or a new style 75 mm nikor. I have a 135 Schneider companon but I can't enlarge enough with it.

    For regular paper printing it is no problem at all and the prints look sharp but enlarging on high resolution film it becomes obvious.

    I wonder if anyone has tried to be that precise with their enlarging and what lens did they find to give optimum sharpness on the edges as well as in the center?

    Yes I am certain I have my enlarger aligned and the lens aligned and I am taping the negative down so it can't buckle or lay unlevel.

    thanks
    Dennis
     
  2. richard ide

    richard ide Member

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    I have done very critical work in the past and have used wherever possible, long focal length lenses using only the center of the image circle. Unless your negative is dead flat, you may have problems. As a cheap check, place a negative between 2 pieces of glass and test. If you are getting out of the optimal enlargement range of your lens, you may have chromatic distortion. I have used a green filter on many occasions to improve image quality.
     
  3. Mick Fagan

    Mick Fagan Subscriber

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    I'm assuming you are enlarging either 135 or 120 film onto 4x5 sheet film, going by your description of lenses you are using.

    Possibly the most important aspect is to keep the negative in the enlarger completely flat. This means keeping it sandwiched between two pieces of glass.

    The best lens I have used for duping or enlarging 135 or 120 film, was an Apo Rodagon f4 90 mm. In my own darkroom I have had wonderful results with my Componon S 50 mm lens enlarging both B&W to B&W to obtain B&W transparencies and enlarging 135mm colour neg to colour print film to obtain enlarged colour transparencies.

    A vacuum easel is handy, but enlarging onto sheet film, a four bladed easel is fine.

    Mick.
     
  4. keithwms

    keithwms Member

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    How about contact printing to the duping film. Then you only enlarge once, for the print.

    To do the contact printing I put the duping film under the negative, and then a big heavy 1" slab of glass atop that.
     
  5. df cardwell

    df cardwell Subscriber

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    What magnification ?
     
  6. Michel Hardy-Vallée

    Michel Hardy-Vallée Membership Council Council

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    Are you checking corner sharpness with the lens stopped down or wide open?

    A wide open lens won't be as sharp in the corners; make sure you know the optimum aperture for your lens.
     
  7. dpurdy

    dpurdy Member

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    Wow a lot of responses. Thank you. I am sorry I made the OP so overly complicated. I could have simply asked the question does anyone know of an alternative brand enlarging lens with better corner sharpness. I have since checked the price of a 105 companon S and at nearly 600 dollars it is out of the question new and there aren't any on ebay so for now I have to make do with the Nikkor I guess.

    In answer to all the questions,
    I am enlarging 6x6 negs onto direct dupe film to 9.5x9.5 inches so an interneg is out and a 105 is the longest lens I can use.

    I have found all my enlarging lenses to be sharpest wide open though they have to be stopped down at least a stop for corner sharpness. I am trying to keep my stop down to one stop.. or f8.

    I go to the trouble of stretching the neg and taping it down and they lay quite flat and I use a cold light so they stay put.

    I used to have all Schneider companons but my 75 and 50 both got hazy so I replaced them with the nikkors. It seems to me that the Nikkors are contrastier. I'm not sure that is a good thing.

    I wish I had the ability to borrow some other lenses to check them but I don't know where to borrow them so I am looking at spending money on faith unless someone can tell me with certainty that a Fuji or something else is better than the Nikkor.

    thanks again
    Dennis
     
  8. pelerin

    pelerin Member

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    Hi Dennis,
    The phrase "with certainty" in the last paragraph makes it difficult to form a response as one person's experience is a rather limited data set. However, with all good will, here is mine.

    As you note the basic question you are concerned with is what lens gives the best corner sharpness when enlarging from MF. My experience leads me to believe that the answer is the Apo Rodagon. (based on blind viewing of test images comparing this and other lenses) This would however, as you suggest in your comment about the new Schneider, be a very expensive upgrade.

    People have suggested that improving the mechanical precision (glass sandwich etc.) of your setup and increasing the focal length in use may yield benefits. I would second that advice.

    Best of luck with your project.
    Celac
     
  9. edtbjon

    edtbjon Member

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    Yes, glass on both sides of the negative will definitely help, especially as you want to work with minimal stopping down. Even though the cold light doesn't produce as much heat as "normal" light does, there is still enough "sway" in a 6x6 neg to cause the problems you experience. As you're already using the sweet spot of the 105, that lens is either a dog or you are having problems with film flatness. My guess is the latter. The only problem with glass is that there is 4 more surfaces that attracts dust.
    (I have been scanning some film lately with film holders from betterscanning.com. While the "ordinary" glassless holders perform well, my results got much better when I bought the wetmouning kit. It's messier and much more time consuming, but worth the extra effort.)
    Also, as I for large format negs use a Durst where I have the option of both cold light and condenser light, condenser light should be prefered in this case. The cold light supresses grain as well as dust, which for most normal printing is good, but in this special case is not what you express you want.
    As a final note, for my 6x6 negs I normally use a Leitz Focomat IIc, which uses glass both above and below the neg. I have not been able to reproduce the sharpness and snapiness of the prints on any other enlarger with glassless holders (including the Durst 138 with condenser light). Still "everyone" says that the Elmar 100mm lens on that enlarger is the weakest link and not on par with the enlarger as such.

    //Björn
     
  10. df cardwell

    df cardwell Subscriber

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    Don't blame the lens. Any moderate quality lens of the past 50 years can do this job. The Nikkor is overkill.

    At the low magnification you are using, no lens is inducing the problem you are having.

    Don't blame the diffusion head. A condensor or point source only adds contrast.

    Your negative is not flat, and no lens will fix that. Use a glass carrier.

    1. Get a glass carrier.
    2. Re-align the enlarger.
    3. OPTIONAL: Use a thick piece of glass to hold the film.
    Adjust the 'glass easel' to be parallel to the film.
    Your print easel may be introducing a problem. Maybe.
    4. Stop the lens down until you see a clear aperture at the corners of the image.

    At this point, if you don't have a dead sharp image, you aren't focusing at the right place.
     
  11. dpurdy

    dpurdy Member

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    All right!!! All Right!! OK!!! I hate glass carriers but I got out one of my old scratched up ones and just to prove you all wrong and... well ok you are all right. It did fix it. Damn. I thought my tape was holding the negative flat. My 6x6 glass carrier bites too much of the image so I guess I will have to find glass replacement for my 4x5 carrier. Now which is worse? Scratches and dust and newton rings or slightly out of focus images?
    thanks again
    Dennis
     
  12. keithwms

    keithwms Member

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    hehe

    Excellent insight df!
     
  13. jeroldharter

    jeroldharter Member

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    You are using a Beseler enlarger, so get a Negatrans film holder which I believe has glass on one side and does hold film flatter because three consecutive frames are positioned in the holder rather than one. It has been awhile for me and roll film. For 4x5, the Negaflat carrier works great without glass.
     
  14. dpurdy

    dpurdy Member

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    Well the good news is that a couple new pieces of glass are definitely cheaper than a 600 dollar Companon S that I was considering. I don't think I have much problem with 4x5 because the film lays so flat anyway and I do always tape it down. Now that I am going to commit to finding new glass and using the glass carrier I am kind of excited about it and maybe will see a difference in my prints. I went to a photography school that taught printing and we used 4x5 glass carriers for roll film. You can take a processed out completely opaque piece of 4x5 film and cut a hole in the center just larger than the negative size then tape your roll film to it with a small strip of silver tape on one edge. I guess I will go back to that.
    Dennis
     
  15. df cardwell

    df cardwell Subscriber

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    With any luck, you shouldn't have dust, scratches, or newton's rings ! The diffusion head covers a multitude of .. well, whatever it is that I do ! You might lay a piece of milk glass or diffusion medium on top of the negative carrier (and remove the diffuser from the bottom of the enlarging head if it cuts out too much light). It will make life a little easier.
     
  16. ic-racer

    ic-racer Member

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    View camera focusing method for enlarging

    You can focus an enlarger exactly like a view camera to obtain optimum depth of field for a curved negative. It is easy if you have markings on your column. Image size changes a little, so it takes some trial and error. Your lensboard position will determine the ultimate projected size of the image and your enlarger head height will determine focus.

    Guess at a lensboard positon ('focus knob' setting) and then don't touch it during this process.
    Move the column up and down to get the center in focus and note the markings on the column.
    Move the column up and down to get the edges in focus and note the markings.
    Split the difference between the two and set the enlarger head there.
    Then stop down and watch the center or the edge and see if you can get it in reasonable sharpness before diffraction takes over. You can just watch the grain as you stop down or, if you like math, you can use this equation based on modular transfer function:

    maximum f number for reasonable sharpness = 20 / (1 + m) sqrt(dv)

    m= magnification
    dv = focus spread, which is the enlarger head distance in millimeters between the point where the center is in focus and the point where the edges are in focus.

    Since using this system of focusing I have found some cases where I can get by without my glass carrier, but sometimes you have to stop down so much that diffraction is an issue.

    BTW, you could do the same thing with the 'focus knob' if you had markings or a scale there, but since most enlargers don't have this, the way described works best. Also, the millimeter 'dv' value in the equation assumes 'back standard' focusing on the view camera, which is the same as moving the whole enlarger head to focus.