closeup filter on a 12-24

Discussion in 'General Technical Discussion' started by manzico, Oct 9, 2005.

  1. I'm getting a 12-24 in a few weeks. I'm curious if anyone has any experience putting a closeup adapter (like the 500D) on one of these. It's not something I would do all that often, but I've seen some interesting results with a closeup adapter and a WA lens. Since I'll be picking up a 70-200 VR in a few months (assuming they're in stock) I'll probably be getting something like the 500D anyway. Just curious.

    Dave
     
  2. nfoto

    nfoto Guest

    The 12-24DX is not just a WA lens, it is also telecentric, thus it behaves differently from others. For example, it has the biggest image circle at infinity and the projected circle actually gets smaller when you focus closer, this is exactly opposite of any "normal" lens. If you put an extension ring on it, you either get vignetting or the focus gets inside the lens assembly.

    My guess is that you might well end up with the focus point being inside the lens, but as the close-up attachment will work with your 70-200, there is no harm done in trying it out on the 12-24DX. If, against expectation, you do get something useful out of such a mismatch, please inform the rest of us.
     
  3. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
    Last edited by a moderator: Oct 10, 2005
  4. interesting...

    All good information. I myself couldn't come up with a particularly good reason to put a closeup filter on a WA, however I remembered reading somewhere that someone had done so and gotten interesting results. Once I get the 70-200 I'll probably pick up the 500D, and once I have it I will give it a try, just to see what happens. I'll be sure to post the results either way. Thanks for the feedback.

    Dave
     
  5. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    Hi Dave, I held my 72mm +3 B+W close-up lens in front of a 12-24DX lens (filter size 77 mm - thus the vignetting) and took this photo in the near darkness of my workroom. Those are the dead batteries from my flash, so this is at ISO 3200:
    [​IMG]
     
  6. nfoto

    nfoto Guest

    I guess it might work at 24 mm, but what about 12 mm?

    Obviously, the increase in magnification attainable with a close-up lens on such short lenses will be minimal, but any closer you can get might be welcome if the quality doesn't suffer too much. So far I haven't seen any good results from close-up + wide-angle unless you achieve close focus by an extension ring, not the front attachment (and extension + 12-24 isn't a feasible approach, I have tried and focus moved into the lens assembly - hardly practical :frown: ).
     
  7. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  8. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    That's at 13mm; at 12mm it just vignetted more.
     
  9. nfoto

    nfoto Guest

    OK, I stand corrected with respect to the potential use of a close-up front attachment on ther 12-24DX. All that remains is seeing the combination being useful for practical photography.

    Just for the record, I'v done a lot of shooting with 20 mm and an ultrathin extension ring (K1) on 35 mm film, so I'm not exactly negative to doing close-ups with wide-angle lenses. But my experiences with dioptre attachments have been you lose a lot of quality (especially in the corners) and you don't gain much in terms of shorter focused distance. If the telecentricity of the 12-24 DX works out to give a better rendition with a quality close-up lens, that is a nice tidbit of information.
     
  10. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  11. Just have time to attach the 500D to the 12-24 and made a test shot. It's a thick filter so vignetting is quite obvious. It's really just a snapshot.

    original.
     
  12. nfoto

    nfoto Guest

    The issue may perhaps not be the thickness of the filter as such, but telecentricy playing dirty tricks with us. As I said before, a telecentric lens has its greatest image circle with focus on infinity and the image circle actually diminishes when it focuses closer. The addition of a close-up lens makes 12-24 DX focus closer, so what we see could be the side effect of that smaller imaging circle. If you increase focal length a wee bit, the dark corners ought to disappear. Try it out, please.
     
  13. nfoto

    nfoto Guest

    Well, you did get closer and I'll guess some curvature is the price being paid.

    Any lens pressed into service for tasks outside its designated area of operation will respond with something peculiar. For more "natural" subjects, the distortion wouldn't matter at all. What's more important is that the field seems to be flat, evenly illuminated, and the rendition sharp into the corners. That's useful information indeed. Oh, where did I put my own 12-24DX? Can't locate it at the moment :frown: I hate the idea of having to purchase a new one just to do this test myself.
     
  14. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  15. Bjørn, just tried it again quickly. The dark corners were gone when zoom to about 14 to 15mm.
     
  16. nfoto

    nfoto Guest

    Have to take you to task here, Paul. The concept of "flat-field" has something to do with curvature, yes that's right, but that is in the "Z" dimension of the image field while geometric distortion ("barrel", "pincushion", "moustache","wave" or whatever they are called) relates to the "X"-"Y" plane. So Chris has shown an example of a surprisingly flat-field lens with strong pincushion distortion.
     
  17. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  18. nfoto

    nfoto Guest

    Nope. No "z" distortion, ie. a flat field. The rulers are presumably flat and are sharp all over their face. Nothing like this would be seen if the lens+close-up attachment had curvature of field (trust me, the occurrence and effect of a curved field I've seen some times before).
     
  19. OK, you got my attention so...

    ...I tried it my myself. 12-24mm with the C500D close-up ring.
    My opinion... why use that combo??? It doesn't provide with any new technic or result...

    @ 12mm
    original.

    @ 24mm
    original.
     
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