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Thread: Size of Lens

  1. #11

    Join Date
    Sep 2002
    Large Format
    Quote Originally Posted by Gary892
    Sandy, you actually elude to the source of the problem. You say as you recall the Nikkor 450 mm M has an angle of view of about 65 degrees, yet when I checked the tech sheet on addorama's website is states an angle of view of 52 degrees. This disparity is part of the problem I am having.

    Thank you to all who have taken the time to responed.
    Gary, perhaps a read of Leslie Stroebel's book might help you get a better handle on this. Manufacturers many times include data that is far more conservative than the actual performance of the lens. They do this because they are talking about the size of the image circle that offers the best image. In the reference you site, they state 52 degrees as the circle that has best resolution with the lens wide open, all lenses as you get closer to the edges loose resolution and preformance, so instead of having people bitch at them they publish very conservative data.

    You know how I find out about a lens coverage? I come to a forum like this and ask about the lens, most of the time people like Sandy, Clay, Thalmann, Don, etc know the answer. But if you really have to know how to make the math, Stroebel's book is the one to read.

  2. #12

    Join Date
    Nov 2003
    Don't worry about it. Some people get upset at the drop of a hat instead of thinking about the question. You are right that the spec sheet says less than what you will see others say here or on other forums. I see two reasons for this. (I did some research on this myself cuz it confused me too)
    --According to calumet the manufacturer posts the image circle knowing that they should be able to get all of the movements necessary without image quality fall off.

    --On a personal note I think publishing the smaller degree or circle size covers their butt.

    Donald is right. Take the word of users over the Manufacturer The user will tell you what kind of movements you can expect on a given size. Ask about a particular lens here or on the LF forum. If there is a user they will tell you about it, and be honest in their descriptions.

    This is another good source. http://www.graflex.org/lenses/lens-spec.html
    Technological society has succeeded in multiplying the opportunities for pleasure, but it has great difficulty in generating joy. Pope Paul VI

    So, I think the "greats" were true to their visions, once their visions no longer sucked. Ralph Barker 12/2004

  3. #13

    Join Date
    Sep 2002
    Omaha, Nebraska
    Multi Format
    This page is on the Large Format Home Page. it is a good place to start for info on lenses by the major manufacturers. Does not specifically cover 12x20 but does have data on a couple of lenses mentioned here.

    "Fundamentally I think we need to rediscover a non-ironic world"
    Robert Adams

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