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Where premium quality meets exceptional value. ZEISS Conquest HDX.

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  1. H

    Two Mechanisms of Vision: Ambient Vision and Focal Vision

    These experiments are scary, but certainly fascinating. Nowadays probably hard to justify ethically. But I guess there must be reports about humans, too, who had accidents or strokes and thereby parts of their visual cortex disabled. Cheers, Holger
  2. H

    Zeiss SFL 10x50 review with digiscoping video samples

    What happens if the object through the binocular is not perfectly in focus, and then we use a phone, which takes videos and therby brings it back into focus? The image may be sharp then, but since it was taken off the prime focus of the binocular's objective, an out of focus CA may be present...
  3. H

    Zeiss SFL 10x50 review with digiscoping video samples

    Dear Piergiovanni, The star test is definitely a very senstitive test. If a binocular offers nice pinpoint stars over large parts of its field, then its optics cannot be bad. In fact, I even detect the deficiencies of my own eyes (due to minor astigmatism) in such a test and need to use my...
  4. H

    Book Review: The Binocular Handbook: Function Performance & Evaluation of Binoculars by Holger Merlitz.

    Great to hear that you guys like my book, it really makes me happy :) Cheers, Holger
  5. H

    Zeiss SFL 10x50 review with digiscoping video samples

    Thanks a lot for this review! I feel better now regarding the 10x50, since I couldn’t detect any excessive CA in the „through the SFL“ videos. It can’t be that bad :) Hope I will have a chance to see this amazingly compact SFL soon, and a comparison with the 10x50 SRBC would be fun! Cheers, Holger
  6. H

    SFL 50mm Second Look - does first impressions really last?

    This would be disappointing indeed. I fully understand that the SFL was not supposed to become an "SF-eater" and that the last notch of performance was intended to be reserved for the higher priced model. But if this now turns out to be killing the SFL due to excessive CA, then the entire...
  7. H

    News from Zeiss - SFL 50

    This was generated by ChatGPT or a similar AI text generator. Cheers, Holger
  8. H

    News from Zeiss - SFL 50

    Here is a publication by Besenmatter about thin lenses for weight reduction: Walter Besenmatter I guess it is not free to download, but somewhere I must have a copy of that. Will check once I am back from vacation. Cheers, Holger
  9. H

    Pincushion 'k' values for more binoculars

    Ok, I have used AFOV = 60 for the 8x42, and AFOV = 61 for the 10x42. These specs had been sent to me by Leica after my enquiry. Seems you have used the measured value from the BINOCULARS TODAY page? Perhaps an inaccuracy of ~0.5° for the AFOV is something we will have to accommodate with. Leica...
  10. H

    Pincushion 'k' values for more binoculars

    Sure, more models will be added gradually when I have the data together and find time. I have just added the SkyRover BC models, which are thankfully specified with their actual AFOV. Regarding the spectacles, I am not sure which are the governing parameters here. I have seen Zeiss advertising...
  11. H

    Pincushion 'k' values for more binoculars

    Sometimes, it depends on which specs are used, the objective angle or the field in m / 1000m. They are rounded differently and may cause some deviations in the k-value. I will later check what was going on there .... Thanks, Holger
  12. H

    Pincushion 'k' values for more binoculars

    I have now started to set up an interactive graphic with some recent binoculars (ChatGPT is my friend), in which the distortion values are plotted over the subjective (half-)angles. Curves of constant k are shown to separate the regions in which a rather strong pincushion distortion should be...
  13. H

    Pincushion 'k' values for more binoculars

    That would be lots of work, but certainly useful. We all should urge the manufacturers to publish the distortion curves of their binoculars, as it is commonly done with camera lenses. Cheers, Holger
  14. H

    Pincushion 'k' values for more binoculars

    This is right, the k-value would become a function of the angle, because the distortion curve is no longer parameterized by any one of the tan(ka) = m*tan(kA) curves. And in case the distortion curve bends down near the edge, the impression of the globe effect is amplified. This is so because...
  15. H

    Pincushion 'k' values for more binoculars

    I would like the idea to have k-values for all binoculars. I am thinking about creating a smarter diagram, where one clicks on the symbol and then gets information about the binocular, because my old version is slowly turning crowded. Maybe ChatGPT can help you translating the program code. I...
  16. H

    Pincushion 'k' values for more binoculars

    The Meostar: 10x42 has 110m/1000m, 6.3° TFOV, 62° AFOV (measured), which yields a k-value of 0.40. The 12x50 has 91m/1000m, 5.2° TFOV, 62°AFOV (measured), which makes a k=0.29. Both have more pincushion than necessary, which is a rather traditional design approach. It gives smooth panning, but...
  17. H

    Pincushion 'k' values for more binoculars

    At this point a big THANKS! to Canip for his efforts in collecting and measuring all those data! For the Nikon E2 his measured AFOV is 68.5°, which would with 8.8° true angle yield a k-value of 0.48. This means there is pincushion distortion, a bit more than needed to eliminate the globe effect...
  18. H

    Pincushion 'k' values for more binoculars

    True, this is because overall the distortion is rather low, typically about 6% at the edge of the field. So the field has to be measured to a considerable accuracy in order to get the calculation of the distortion values accurate. In some cases, the magnifications are rounded, such as 8x instead...
  19. H

    Pincushion 'k' values for more binoculars

    OK thanks, if the UVHD+ has 8 degree, then I get k = 0.34! Cheers, Holger
  20. H

    Pincushion 'k' values for more binoculars

    Right, and I need the specified true (objective) angles (or fields of view), which are usually more or less reliable and which I have just looked up on Internet. Assuming all data, including magnification, being reasonably accurate, I got: Model, AFOV, TFOV...
  21. H

    Pincushion 'k' values for more binoculars

    To calculate the k-value, we indeed need accurate data for the AFOV, but those are more often than not just approximated by simple formula. Zeiss uses for the HT-range the multiplication of objective angle with the magnification, which always yields k=0, and Nikon uses that ISO-norm formula...
  22. H

    Two Mechanisms of Vision: Ambient Vision and Focal Vision

    This may be something useful for the hunter, less so for the birder. You need a reasonably large target so that you can identify it with the bare eye. Under low light, this becomes generally difficult because we need the binocular and its power to raise the threshold contrast for visibility...
  23. H

    News from Zeiss - SFL 50

    A real bummer! Also, when presenting the properties of the three new binoculars, he only talks about magnification, no mention about the 8x50 being a low light specialist or such. He essentially says that whoever can accommodate with 8x should get the 8x50, those who want to see it all will go...
  24. H

    Two Mechanisms of Vision: Ambient Vision and Focal Vision

    Maybe with digital binoculars: They could have an eye tracker, and once the eye fixates an object for more than half a second, it could zoom into that object. So there would be a search mode at low power and an observation mode at high power. But then, I would prefer having the control in my own...
  25. H

    Two Mechanisms of Vision: Ambient Vision and Focal Vision

    Distortion is primarily generated in the eyepiece, whereas the prism does not contribute here. Cheers, Holger
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