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Thread: LF lens manufacturer philosophy

  1. #21

    LF lens manufacturer philosophy

    Chris, I believe that the Super Angulon 72mm XL does have an image circle approa ching 259mm, or at least pretty close. Alan has one, he could probably verify t his.

    Perhaps LF lens designers could come up with a 58mm XL or a 47mm XL with a large r image circles than 166mm; a new line of XXL's? Schneider and Rodenstock have been offering shorter lenses with larger and larger image circles in recent yea rs. I think that trend is great; they shoud keep on pushing the envelope.

    The cost might be prohibitive, though. And I question whether the demand (or ne ed) for such lenses would justify the high design and manufacturing costs. I'm not a lens designer, but I would think that at some point certain design limits will be reached.

    But, as it stands now, these lenses (45mm, 47mm, 58mm) provide a marginal usable image circle for 4x5. That makes them more difficult to use well. It is very easy to displace such a small image circle. That is why most people would advis e against getting one of these as your first WA lens.

    These ultra-wides do work particularly well for interior architecture, particula rly in tight, cramped situations, precisely because they are often focused at di stances much closer than infinity, increasing their usable image circle. This g reater bellows extension, and the resulting increase in usable image circle, wil l allow for greater movements in situations when they are most needed.

    I believe Alan is correct--the longer the focal length for a given format, the g reater the need for larger image circles to allow for movements. For a variety o f reasons, the degree of Scheimpflug tilts/swings necessary with wide angle lens es is much less than with longer lenses.

    I believe this would also hold true for shift movements. (You know, I cannot rec all the last time I actually used a shift movement with a WA lens.) Your plaus ible theory that greater shift movements might be necessary with WA lenses, part icularly when the lens is positioned closer to a subject, would probably be offs et by the very substantial decrease in magnification with WA lenses, when compar ed to longer lenses.

    Have you noticed how very tiny things look on a 4x5 groundglass with a 58mm WA? I would not take much of a shift with a 58mm to achieve the desired effect, no matter how close the subject.

    Keep up the questioning attitude. Take care. Sergio.

  2. #22

    Join Date
    Feb 1998
    Posts
    287

    LF lens manufacturer philosophy

    If your desire is to get a 600mm lens cheaper because its optimized for 4x5 is i snt reasonable because the cost you are paying for that 600mm isnt because its h ard to make, but because its a limited market. Long lenses are easy to make, optically. Even narrow angles of illumination end up with far more coverage than you need. Thats just the way lenses work. You ca n make a very usable lens for 4x5 with only 1 element. Or maybe, try no lens at all. (check out the latest issue of View Camera mag. for an article on pinholes on LF. Surprisingly sharp!) Maybe have some fun and experiment. Order a cheap le ns element from Edmond Scientific for a couple of dollars, and see what you get on the ground glass. If you really want a super image, spring for an achromatic (2 element) lens. Try even longer focal lengths. The longer the better, opticall y. Try mounting them in a lens cap or something. The image you get on the ground glass may suprise you with its quality. It will be better than a pinhole, which is already pretty good at these focal lengths, and its fun, too. Get your kids involved, as well, as this is something they will enjoy.

  3. #23

    Join Date
    May 1998
    Posts
    218

    LF lens manufacturer philosophy

    Regarding the 72mm lens: yes, the claimed circle is 226mm, rather than 166 for b oth the 58mm and 47mm. It seemed to me that Chris was getting confused between t he 58mm and 72mm, but it didn't substantially affect the conversation, so I didn 't mention it.

    I also don't shift very much. I do tilt/swing, and just remember not to tilt/swi ng the 47mm lens, but to do this to the film back instead.

    I was exploring a cupboard the other day, and came across my experiments that we re pretty much as Ron describes. Close-up lenses, single element, +2 and +3 diop tre (500mm and 333mm, or 200mm with both screwed together). A cardboard lens pan el, with a step-up ring glued in place, to take one of the close-up lenses. Blac k cardboard circles, with holes, making the apertures. The shutter was of the "h old your hat over the lens" variety. I was playing with 5x4 and 10x8, and the re sults were, well, OK. Much better than pinholes, but much worse than "real" lens es. Also, of course, very much cheaper than "real" lenses.

    Kids are an accessory I don't have, but I suppose they would be useful for luggi ng the gear around.

  4. #24
    Confidently Agnostic!
    Join Date
    Aug 2006
    Location
    Victoria BC
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    1,062

    Re: LF lens manufacturer philosophy

    Boo. Pointless pre-halloween ghost thread revival!

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