Testing macro lenses

Discussion in 'Lens Lust' started by genehsu, Jul 18, 2007.

  1. genehsu

    genehsu

    594
    Apr 15, 2007
    Seattle
    Anyone have good ideas about what to test for and how to test macro lenses? I have or can borrow a bunch of them, and it would be interesting to see the differing characteristics in a side-by-side test. This will probably be a long-term project since I only have an hour or two here and there to devote to this project.

    The test candidates:
    Nikkor: 60/2.8AF, 55/2.8AIS, 55/3.5AI, 85PC, 200/4AF, 200/4MF
    Tokina: 90/2.5MF (3 copies) + extender (2 copies)
    Vivitar: 90/2.5MF (Series 1, no extender, same optics as Tokina)
    Elicar: 90/2.5MF
    Lester Dine: 105/2.8MF

    If anyone is close to San Francisco and wants to add to the list, I'm sure one or two more lenses won't hurt.

    My impressions so far after shooting macro with the D70s is that every one of these lenses should out-resolve a 6MP sensor. I haven't found any pixel blur that I couldn't attribute to user error. It's mostly about things other than sharpness, though the D2X might be able to pick off the worst in sharpness.
     
  2. Leif

    Leif

    Feb 12, 2006
    England
    DOF is a product of the physics not the design, so I think you want to test resolution and contrast (though the two are closely related) using a flat target with plenty of detail. You might want to go to ~1:2 or at least 1:4 i.e. the region where such a lens should sing. I don't think distortion is so interesting as all these micro lenses seem to have very little anyway.

    You also need a good tripod and head, cable release, mirror lock up, lens hoods, probably several exposures per lens to get good focus, 100% crops from the centre, half way to the edge and the edge, at various apertures down to F22 at least. ISO 100, and consistent lighting help.

    I found focussing a 200mm micro at F4 very tough hence multiple exposures.

    Here is an example:

    http://www.nnplus.de/macro/Macro100E.html

    Have fun. :)
     
  3. genehsu

    genehsu

    594
    Apr 15, 2007
    Seattle
    I'd expect to hit the diffraction limit before hitting the minimum aperture for each lens. Yeah, I didn't expect this to be easy. I'd also expect to use a focusing rail so that I can set a consistent magnification for comparison.
     
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