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Thread: Trying to sort out Dagors

  1. #41
    Mark Sawyer's Avatar
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    Re: Trying to sort out Dagors

    Quote Originally Posted by Bernice Loui View Post
    What I do not understand is why and how Plasmats have pretty much taken over the majority of modern LF lenses, given many times LF lenses are used at apertures f11 and smaller for most work. Exception being portraits and the want for that look in which case a Tessar or Heliar or Gasuss (large, heavy and lots of elements to cause flare, which demands multi-coating to control properly) design may be preferred.
    Dagors have a focus shift due to zonal spherical abberation. This gives the "sharp but smooth" look of a wide open Dagor that some like, especially for portraits. The additional design freedom of the Plasmat allows designers to eliminate that focus shift, which is why Plasmats became popular after coatings came in. Wide open Plasmats tend to look a bit harsh due to the lack of aberrations, but that's the price of getting rid of the abberations/focus shift.

    Some may prefer the look of a wide-open Dagor while others prefer the look of a wide-open Plasmat, and some may like this for this but that for that... Stopped down, Dagors and Plasmats look pretty much the same, with the Plasmat having slightly less coverage due in part to the slightly longer barrel owing to the additional air spaces.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  2. #42
    Mark Sawyer's Avatar
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    Re: Trying to sort out Dagors

    Quote Originally Posted by goamules View Post
    The big uncertainty I have is the so called Gold Rim Dagors, which if I'm reading correctly were not called that by Goerz, but they did call some Golden Dagors. Does anyone have a Goerz catalog or advertisement from the Golden Dagor era, with pictures? That title is found in some 50s ads in Google Books, but only snippet view. I want to see what they look like in the front based on the advertisements, not on internet anecdotes. I see a lot of Dagors with various gold rims, probably a dozen on Ebay right now, and find it hard to believe there was a cottage industry of elves polishing paint off regular lenses.
    There are at least two varieties of "Gold Rim" Dagors: The conventional mount with the front rim polished to reveal the gold-ish hued brass, and a later style with a noticeably larger gold-anodized aluminum front rim. I think both came as factory finishes, but a non-gold rim Dagor of the right vintage could be polished to reveal the brass underneath. If it's a coated Dagor from the same manufacturer and similar vintage, there should be no difference in performance.

    I tend to agree that there's no "cottage industry of elves polishing paint off regular lenses." If there were, we'd see a much wider variety of Dagors with gold rims. The early gold rim Dagors are always "C.P. Goerz Am. Opt. Co.", while the later aluminum rims seem to be from "C.P. Goerz Am. Opt. Co." and "Goerz Optical Co. Inc." And I've never seen someone polish the rim of an uncoated Dagor.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  3. #43

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    Re: Trying to sort out Dagors

    Ease up there, Hoss. We're ALL guilty of occacionally replying to a thread without having actually first read the whole question.
    Wilhelm (Sarasota)

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