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Cocklebur or Xanthium strumarium 1.75x, f6.3, EAf17.3, 1/20sec, ISO100, 172 micron per step, 69 steps_2024-05-26-06.52.27 ZS PMax Geotagged,Rough Cocklebur,United States,Xanthium strumarium Click/tap to enlarge Promoted

Cocklebur or Xanthium strumarium

1.75x, f6.3, EAf17.3, 1/20sec, ISO100, 172 micron per step, 69 steps_2024-05-26-06.52.27 ZS PMax

    comments (3)

  1. View Jon Reck's profile
    Jon Reck
    Lion
    View Lion class
    What does EAf mean? Posted one year ago
    1. View William Bodine's profile
      William Bodine
      Lion
      View Lion class
      EAf is my abbreviation for Effective Aperture. Effective aperture refers to the actual amount of light that passes through a lens and reaches the sensor, especially when dealing with macro photography. As you increase the magnification beyond 1:2, the effective aperture changes because the lens is physically further from the sensor, affecting exposure, light diffraction and depth of field. I usually try to keep the EAf to below 19 because light diffraction starts to blur the image at smaller apertures. There is a mathematical formula to calculate this number, but I use the tool found in Zerene Stacker to find the Effective Aperture. Posted one year ago
      1. View Jon Reck's profile
        Jon Reck
        Lion
        View Lion class
        Thank you. That seems like a useful tool, missing in Helicon.
        I ran a series of resolution testing photos using my Laowa 2.5-5x (of an EPROM chip circuitry) and found that even at 2.5x, resolution was degraded stopping down from f2:8 to f4, and the degradation was more noticeable as magnification increased. I’ve been stopping down to f3.4 or f4.0 on the lower magnifications if color aberrations are a problem and that seems to help, a little.         Posted one year ago

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The Rough Cocklebur

''Xanthium strumarium'' is a species of annual plants belonging to the Asteraceae family. It probably originates in North America and has been extensively naturalized elsewhere.

Info 4 0
Similar species: Asterales
Species identified by William Bodine
View William Bodine's profile

By William Bodine

All rights reserved
Uploaded May 26, 2024. Captured in 3042 E Adobe St, Mesa, AZ 85213, USA.
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