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pellopt last won the day on 2 August 2018

pellopt had the most liked content!

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About pellopt

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  • Birthday 14/04/1940

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  • Real Name
    Samuel Pellicori
  • Gender
  • Location
    Santa Barbara, CA
  • Photographic Interests
    optical art, macro, insects, nature
  • Edit my pics?
    Ask Me
  • Fav. Camera
  • Fav. Lens
    18-135mm Nikon zoom
  • Fav. Editor
  1. pellopt

    Samuel Pellicori

    Cirrus clouds against a polarized sky.
  2. pellopt

    Munich Square

    by Samuel Pellicori
  3. pellopt

    Succulent Petals

    by Samuel Pellicori
  4. by Samuel Pellicori
  5. by Samuel Pellicori
  6. by Samuel Pellicori
  7. Pretty colors, but unnatural. See your first (unfiltered) for the accurate reflected water coloration.
  8. pellopt

    Pellicori macros

    insects, opt art, misc
  9. pellopt


    various photos
  10. Color around edges such as distant branches (and small openings) can be due to diffraction. Diffraction of light creates colored "fringes" by spatially (angularly) separating the different wavelengths of light. (similar to, but in the opposite dispersed color spread direction produced by a prism). It is possible that the lens does not recombine the separated colored spectrum completely (residual chromatic abberation), and therefore a purple satellite image will be recorded. This effect is subbdued when there are not sharp edges present.
  11. pellopt

    D80 UV Range?

    How may I obtain a copy of the spectral response curve that is shown? Thank you, Samuel
  12. Both "dichroic" and interference filters are constructed of multi-layers, the both function as interference coatings. A "dichroic" filter reflects a certain band (say the NIR region) and transmits another (say the desired UV band). A narrow band pass filter constructed only using interference filtes can be fabricated that passes any UV band desired, but will require a hundred layers. Selectively absorbing glasses such as offered by Schott (UG-11, for example) make the job easire since they absorb all visible and most of the near IR. The Baader (and similar UV-transmitting filters) use a selectively absorbing glass to define the UV pass band and a stack of interference filters to help reject the Near Ir where the color filter glass has a leak. This interference filter type is called a 'short wave pass' (SWP) filter. There is essentially no angle dependence becase the UV passband is determined by the absorbing glass, and its passband does not shift with angle unless one goes to extreme incident angles like 60 degrees (half-angle). The cut-off edge of the SWP interference filter will shift shortward at larger incidence angles ... field angles. However it will not encroach on the UV band. If the designer is smart, it also will not shift to wavleenghts thet the glass leaks. So there is no performance difference for the same filter design whether its size is 2 inches, 67mm or 77 mm (or 140 mm !). The difference is cost. That's a major reason that why my proposed filter will br more expensive. Hope this helps, Sam
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