50mm still ok for bigger prints?

Discussion in 'Enlarging' started by Quinten, Jan 13, 2006.

  1. Quinten

    Quinten Member

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    Hello,

    The enlargers I use all have a 50mm and I am just wondering wheter the sharpness is affected when the lens is far from the table on wih I lay my paper. With prints above 50cm lenght it is a lot harder to see grain in the sharpening tools. The edges seem to become less sharp as well although I can't really put my finger on it, it's just a feeling and I might be wrong here.

    cheers!
     
  2. Ole

    Ole Moderator Staff Member

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    Different lenses are optimised for different enlargement factors. It's a design specification, not a result of the focal length.

    But it could be that you've reached the limit of usability with yours.

    It could also be that the enlarger is out of alignment, or the grain focuser is out of whack, or...
     
  3. firecracker

    firecracker Member

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    I'm assuming you're talking about the distance between the lens and the paper when enlarging an image. The higher the enlarger head is, the softer the image gets. You need to adjust the contrast and add more time.

    But the "less sharp" doesn't mean blurry just to be sure.

    If you're using 35mm negative, 50mm is the normal setting and give you the closest range. If you go up the number, you simply have to raise the enlarger head higher, and that makes everything less stable.

    And as you said if you're trying to make real large prints, the 50mm is the best way. You could use 63mm or 75mm for compensation, but you have to watch out the height for the head to go up.

    I use 63mm lens, and that's flexible for all the sizes of the images I normally make (on 8x10, 10x12, 11x14, and 16x20" sized paper). But when I go for real large prints (16x20" and up), I will have a 50mm lens as an option, and when I go as small as 5x7" or so, I will switch to a 90mm lens, so I don't have to lower the enlarger head so much.

    If you can't see your grain sharp enough, that probably has to do with either the focusing system on on your enlarger or the grain focuser itself. Also, if you're using the Omega D2 or LPL 7700 types of condenser heads, you have to set the condenser lens according to each specific lens type, otherwise you will have trouble focusing the image.

    And if you're getting the edges of the image blurry, you have to close down the apature on your lens. Stay with F8 or higher numbers, though it depends on how the image appears. But anyway a 50mm lens is what you need. :smile:
     
  4. Helen B

    Helen B Member

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    For enlarging lenses, in general the shorter the lens the higher the optimum magnification it is designed for. A 50 mm is probably best at 10x but the manufacturer's spec might say that it is good up to 20x.

    We old-timers can remember a company called Nikon, who used to make quite decent enlarging lenses. Their 50 mm was best at 8x, but 'usable' from 2x to 20x. I never paid much attention to the 20x limit. The 40 mm f/4 EL Nikkor is better for high magnification though.

    Best,
    Helen
     
  5. Claire Senft

    Claire Senft Member

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    If you wish to get better sharpnes at high magnification ratios here are three lenses designed for that work.

    50mm Rodagon G
    40mm 5.6 Zeiss S-Biogon
    60mm F 4 Zeiss S-Orthoplanar.

    The two Zeiss lenses are exceptionally good and are designed for magnification ratios of 10-70x. They are very hard to find. The 40mm S-Biogon has no aperture. It comes with a graduated ND filter for exceptional smoothness On Ebay thes have been going, when available for about $500.00
    The 60MM S-Orthoplanar is exceptionally hard to find, The only one that I have seen sold on Ebay sold for $2000.00 2 years ago.

    Zeiss states on their website in Camera and Lens news that with 10-70x magnifications these lenses will far out preform anything on the world's market.

    Theses 2 lenses were originally offered for reprographic work. I understand
    that they originally sold for circa $20,000.00 each.

    The Rodagon G is designed for a 20x magnification factor.
     
    Last edited by a moderator: Jan 14, 2006
  6. photobackpacker

    photobackpacker Advertiser

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    So far, nobody has mentioned film format - a 50mm enlarger lens is considered a suitable for enlarging 35mm negatives. Purists have tended to move up to an 80mm in the belief that there would be less light fall off and increased sharpeness. Fred Picker led the charge in this belief - recommending the 80, 100, 135 and 150 lenses for the 35, 2 1/4 sq, 2 1/4 X 3 1/4 (6X7mm) and 4X5 formats, respectively.

    While I found Fred to be a wee bit dogmatic :wink: in certain areas, I think he was correct here and have used those lens/format match-ups with good success.

    If you find, by the way, that you need to increase contrast as you make larger images - you have a fogging problem in your dark room. (either exceeding safelight limits or other non-image light striking your enlarging paper.) Exposure times will increase but contrast will not change - provided you have a non-fogging environment.

    For what it is worth. :smile:

    Bruce
     
  7. df cardwell

    df cardwell Subscriber

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    If I recall my Rodenstock tables correctly, the Apo Rodagon N is optimised for a range to 20 x. At 20 x it bareley outperforms the Rodagon G, which is optimised from 25 x to 50 x.

    Also, an f/2.8 lens is diffraction limited by f/ 5.6. At 20x, my Rodagon N is noticeable better at f/4.5 than f/5.6.

    When we get up to 16x20s, it becomes important to study the focus carefully across the field. Minute irregularities become evident: the easel may be out of true, not to mention a barely out of alignment enlarger. A glass negative carrier is essential.

    Older enlarging lenses ( El Nikkors, Apo Rodagons, Focotars ) may display anomalies such as a doughnut shaped area of sharpness as we exceed its range, and the only alternative is to stop down... thereby eliminating the anomoly, but at the cost of overall resolution.

    As for Mr. Picker's preference for longer enlarging lenses, I always suspected it had more to do with the mechanical system of the 4x5 enlarger lacking the discretion to focus accurately a shorter enlarging lens.
    An 80mm Apo Rodagon ( or any other common 80mm lens ) is optimised for lower magnification work. So there was no optical foundation in using longer lens.

    Oh, well. it isn't THAT big a deal most of the time.
     
  8. Quinten

    Quinten Member

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    fogging?

    Whow the contrast is a striking comment. I had some notes from an earlier print of this neg and just copied the paper grade, I thought it was subject to taste but I indeed went one grade higher for this larger print.

    I supose fogging also affects the sharpness when this is the case.

    Can fogging acure sooner because the wall behind the enlarger is white (as is the ceiling) and I tent to use longer exposures (around 15 sec and up to 4 minutes when you add all burning.)

    It's the only professional darkroom I know wich has white walls ceiling and floors.... They might have to ask lower subscriptions:smile:
     
  9. df cardwell

    df cardwell Subscriber

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    Everything can be white in the darkroom... EXCEPT around the enlarger.

    When you make big prints, you need to even be sure the ENLARGER post or chassis isn't a cause of flare.

    Not to mention the longer time yuo're exposing the paper to a safelight !
     
  10. Monophoto

    Monophoto Member

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    Quinten - -

    As the degree of enlargement increases, both the grain in the film and any abberations or deficiencies in the optical system become more noticeable. A 4x5 print from a 35mm negative made with a 50mm lens can look very sharp, but if you make an 11x14 enlargement from the same negative, and using the same enlarger and lens, you will see more grain, and any softness in the resolution of the lens will become more obvious. Likewise, any problems with alignment will be more visible.

    The other issue here is viewing distance. You will always see more grain and optical defects if you are viewing a print from a close distance than you will if the print is further away.

    I've made cropped 11x14 prints from 35mm negatvies using a 50mm el Nikor lens where the full frame enlargement was more like 16x20 inches. They weren't the same quality that I get from a 4x5 negative, but they weren't all that bad either.

    Kodak used to brag about making an enlargement for the 18 x 60 foot Colorama display in Grand Central Station in New York from a 35mm Kodachrome slide original. Now that's serious enlargement.

    There is no absolute rule on how much enlargement you can squeeze out of a negative - as the artist, you have to decide when the optical defects take away from the content of the image.
     
  11. firecracker

    firecracker Member

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    Be careful with your 4 min. burning-in, which could cause some fogging in some areas of your print if the light was bounced off. Covering the areas of the paper that you're not touching may help eliminate the potential problems.

    And keep all the shinny and reflective things away from the enlarger, such as the grain focuser (with a mirror), the plastic top for a filter box, and etc. :smile:
     
  12. George Collier

    George Collier Member

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    Ditto the comments above on long burning in times / reflective surfaces around the enlarger. I saw pictures of Harry Callahan's darkroom once, a simple and unglamerous arrangement, but what I remember was a large black cloth draped or attached to the wall all around the enlarger - no painting of walls necessary, although watch out for dust (choose the fabric wisely). Also, burning in tools, like cards, etc should all be black, at least on the bottom side to avoid reflections up off of the print and back down again during the burning in process. To compare - do a test strip twice with the card a couple of inches off the paper, one with a white card, one with a black card, process together, you will see the difference.