coated versus uncoated lenses

Discussion in 'Large Format Cameras and Accessories' started by spoolman, Mar 19, 2010.

  1. spoolman

    spoolman Subscriber

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    What are the differences in image quality between an uncoated and a coated lens?.I'm currently contemplating purchasing a 127 mm Kodak Ektar 127 mm Lens in a Supermatic shutter.Any help would be gratefully accepted.

    Thanks,

    Doug:smile:
     
  2. jamesgignac

    jamesgignac Member

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    From what I've heard coating only lends a hand with regard to colour photography. I've been meaning to look into what it actually does...I'm anxious to follow this thread and find out from one of the more clever folk.

    Sorry I couldn't be of much help :/
     
  3. pgomena

    pgomena Member

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    Lens coatings serve to reduce flare and internal reflections between air-spaced lens elements. This improves color saturation and image contrast. Uncoated lenses will give a more pastel, less saturated color image in some circumstances. Avoiding high-flare situations and using a good lens hood will help fight flare with any lens, but especially with uncoated lenses.

    Peter Gomena
     
  4. richard ide

    richard ide Member

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    Coating also dramatically increases light transmission. Not as noticeable in LF lenses but some lenses for small format can have over a dozen elements. Without coating some designs would not be practical because of light loss.
     
  5. Shan Ren

    Shan Ren Member

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    As already stated, coating helps increase contrast. Uncoated lenses can be very nice. More shadow detail and what I call "transition". I often use older, uncoated lenses, especially for b&w. They also have a tendency to flare, which is good and bad, depending ....
     
  6. Ian Grant

    Ian Grant Subscriber

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    In many ways it's easier to say what coating does and the benefits, and some lens designs benefit far more than others, so much so that coating made some lens designs practical.

    Coating works by cutting light scatter at glass/air interfaces so the number of elements and how they are grouped is important. The more light scatter the lower the contrast and the higher the more potential of flare.

    An uncoated Tessar has 4 elements in 3 groups so 6 glass/air interfaces, while a Dagor has 4 elements in 2 group so 4 glass/air interfaces, but a Eurynar or Celor has 4 elements in 4 groups so 8 glass air interfaces and is the most prone to flare and lower in contrast.

    When these uncoated lenses where in production films (or plates) had thicker emulsions and were usually processed to higher contrasts, negatives were usually not greatly enlarged or contact printed.

    With modern films (B&W or Colour) uncoated lenses can with care give very good results, but there's a drop in micro contrast and fine definition, and as others have said flare can be a problem if shooting into the light. The internal light scatter gives rise to what many refer to a s a more rounded look, the scatter also tends to boost shadow exposure sligthly.

    Early lens coatings can vary in quality and effectiveness, often having quite a marked effect on colour transmission/balance, I have a T (coaterd) Zeiss Jena 150mm Tessar that gives a very noticeable bluer image, it's heavily coated and a great lens for B&W. Some refer to these lenses as “Single coated” but in practice many of these lenses had more than one coating and manufacturers refer to them as “Coated”.

    The coatings on some lenses made in the 60's & early 70's is almost on a par with modern Multi-coating, but you need to learn how your own uncoated & coated lenses behave as there's so no hard & fast rules.

    Ian
     
  7. mjs

    mjs Member

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    What they said. Uncoated lenses generally give negatives of lower contrast. This is often visible as more "open" shadows (more shadow detail, sometimes,) and more flare around highlights. Because of the lower contrast and greater flare or ghosting of highlights, some will interpret the negatives as being "softer" (not as sharp,) as a negative from a more modern, coated lens. In general, I think that's true: older lenses sometimes aren't as sharp as modern lenses. Sometimes, with the simpler designs (designs having fewer glass elements, such as tessars,) sharpness is actually quite high. You can use a yellow filter to increase contrast if the lens is adequately sharp otherwise, and get negatives with what most would consider "normal" contrast. I also fancy that a high-quality, modern coated glass filter over the lens also helps with flare, although you absolutely still need to shade the lens from direct sunlight (or, really, strong direct light from any source.)

    Personally, I don't care for uncoated lenses for negatives I intend to enlarge but with a yellow filter, and if adequately sharp, they're marvelous for negatives to be contact printed.

    Mike
     
  8. spoolman

    spoolman Subscriber

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    Thank you all for your opinions.This just re-enforces how great this organization is when it comes to this type of subject matter.I count myself lucky to be a part of it.

    Doug:smile:
     
  9. Ian Grant

    Ian Grant Subscriber

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    I missed your second question about the Ektar, for 5x4 it won't be the greatest in terms of performance, it's a Tessar type design and edge sharpness won't be good until f22 and coverage will be tight no room for movements.

    Some people swear by then but I wouldn't expect to much from one,

    Ian
     
  10. John Kasaian

    John Kasaian Member

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    The 127 Ektar is a very nice lens for use on Speed Graphics. I have an uncoated version and I can't think of any reason to move up to coated---even for color photography There just isn't a lot of wiggle room.
    That said, the difference between single coated and uncoated is significant especially when a design has a greater propensity to exhibit flare. OTOH the difference between a single coated and multi coated lens is so subtle that it is a non issue for my work.
     
  11. jamesgignac

    jamesgignac Member

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    Shan, Ian,
    I always judge by performance first and some of my favourite lenses are some of the quirkiest (my Agfa Isolette, for example, is a real charmer.) I certainly have paid attention to the hype over lens coating, however, and my 'professional' gear is all slopped up with the stuff and I certainly can't complain about the results I receive...that being said I just like taking pictures no matter the lens involved :smile:

    Thanks for all of the info and thanks to you spoolman for starting the thread!