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  1. Surveyor

    Someone knows the name of this scope/binocular?

    Google Abney Level.
  2. Surveyor

    Bill Cooks book now available

    My copy will be here tomorrow.
  3. Surveyor

    Eclipse

    One of the better papers on the subject, 2016, from the American Astronomical Society. Check Chou's credentials.
  4. Surveyor

    Eclipse

    Hi Binastro; I am lucky enough to live on the path of totality and it was a very interesting afternoon. As a retired surveyor I have a lot of solar filters lying around, 3 Topcon and about 25 of the Thousand Oaks band pass type, aluminized on glass (580-630 nm). I put a couple of these on a...
  5. Surveyor

    Nikon Monarch HGs in Cabelas Fall Catalog

    Yes, I can not get the camera close enough, the lens are touching here, but this is the same thing I see with my eye and I can see full FOV but I can only keep the spot within a less than a quarter degree of center due to eye movement. EDIT: I can get to the exit pupil by zooming but can not...
  6. Surveyor

    Nikon Monarch HGs in Cabelas Fall Catalog

    Hello Kimmo, thanks for dropping in. I was going to take a 10x40 monocular with about a 35 mm obstruction and place it on a tripod and try from normal setting for me, which shows a 4.2° FOV and start backing off from the bino to see if as the FOV shrinks, indicating being on the optical axis...
  7. Surveyor

    Nikon Monarch HGs in Cabelas Fall Catalog

    Thanks Henry; One other thing, if you try the experiment, use the eyecups as you normally use them. I could duplicate Henry’s results, but only by fully collapsing the eyecups to the point I would get blackouts in any case, inside the exit pupil and using one eye. Henry, are you using your...
  8. Surveyor

    Nikon Monarch HGs in Cabelas Fall Catalog

    Hi Henry; I have no problem with “mechanically stopped” aperture changing resolution. The part I have been having a problem with for a long time is that the eye can stop an aperture that it can not even see. The only thing the eye can see is the already formed exit pupil. On page 171 I take...
  9. Surveyor

    Nikon Monarch HGs in Cabelas Fall Catalog

    Over many years I have tried to verify this theory and, so far, the great majority of the circumstantial evidence is that this is fiction rather than fact. I have not been able to find a source for this theory other than talk forums and would welcome any experiments that would prove this point...
  10. Surveyor

    Transmittance and visual perception

    No Nix, my IOL's were simple biconvex with UV blue blocker made by Alcon. At the time I worked outside a lot of the time. My vision was not bad, about 20/25 to 20/30 at that time and the IOL's were only 1d difference. I have been pleased with the results. I have attached the Alcon propaganda...
  11. Surveyor

    Noctivid overdrive past infinity

    Thanks Renze, Assuming the close focus was measured with the binocular diopter set to 0 the approximate overdrive would be -3.72 based on the supplied information. If the binocular diopter is set to some other value, it would either add or subtract from the overdrive figure. FWIW, most of the...
  12. Surveyor

    Noctivid overdrive past infinity

    Renze what is the power and close focus distance of your example?
  13. Surveyor

    Owners: How Are Your Leica Noctivids Serving You?!

    Hi Rathaus; Henry has already given all the information you need to measure field curvature in the paragraph quoted. All you need is a flat target that covers the field of view and some way to measure diopter (this can be converted to meters if needed). For the amateur the following are useful...
  14. Surveyor

    Big fan of Porro prism .

    I love it. Should be the official name of the 12x50 BN. A very good optical device, a better than average defensive bludgeoning device and with a little longer strap, suitable for beating bushes down for trail breaking.
  15. Surveyor

    Leica 8x32 BA

    I just checked my SN. Probably older than your sample by quite a bit, 10242xx. I am pretty sure I got mine new in the 1991-1993 time frame.
  16. Surveyor

    Transmittance and visual perception

    How right you are. Several years ago I had cataract surgery and afterwards car headlights and other things started appearing very bright and a lot bluer, to the point of being just plain annoying. Since then my eye/brain perception has returned to my pre surgery perception of color, and my...
  17. Surveyor

    Transmittance and visual perception

    Prompted by some comments in the Leica BA 8x32 thread I thought I might make some observations for general comments. It is obvious that there is a lot of misunderstanding about the value of transmittance curves on the forum. A transmittance curve is a radiometric measurement of spectral color...
  18. Surveyor

    Leica 8x32 BA

    Binastro; Back in 2008 I sent several binoculars to Orb, one of the better NIST/ISO labs in the states, to get a reference for my transmittance setup. Attached is their report for my 8x32 BA. Edit: Binastro, I forgot to mention that the original did not match my measurements and then noticed...
  19. Surveyor

    Big fan of Porro prism .

    Hi David, my acuity for my right eye is routinely checked by USAF target at various known distances, example, group -2 element 5 at 6 meters or group 0 element 3 at 2 meters. I am not sure what my vision is in 20/20 terms since it has never been measured by that definition although I assume...
  20. Surveyor

    Big fan of Porro prism .

    Hi Bill, I added the last paragraph as an edit you may not have noticed. Not everyone can get full resolution with their eyes if the hardware does not match up. As to location, you may remember some of our email discussions in the past about Cleveland, Ooltewah and Indian mounds near your old...
  21. Surveyor

    Big fan of Porro prism .

    Hi Bill, I thought I would take a whack at this while David gets his thoughts together since I used to do more of it in the past than anyone else on the forum. The key to taking the eyes out of the equation is magnification. My visual acuity is pretty poor, about 90”, or about twice as bad as...
  22. Surveyor

    Big fan of Porro prism .

    Hello Henry, hope you had a nice vacation. Have you used a NBS 1963A target? I find they have the advantage of longer lines but I find them very hard to use on boosted optics. The USAF 51 target is nested so as you zoom in the relative position stays the same, with the NBS target when you...
  23. Surveyor

    Help with Diopter ring on RSPB HD 8x42

    I have one binocular (a Zen-Ray) that you have to pull the diopter ring up about 1 mm, set the diopter, then push back down to lock it.
  24. Surveyor

    New 32mm Trinovid binoculars

    Hi Binastro, This information is probably already somewhere on the forum so I will give an abbreviated overview of simple collimators. A collimator is nothing more than lens (better quality lens give better results) with an image or reticule at the prime focus. See the pictures attached. The...
  25. Surveyor

    New 32mm Trinovid binoculars

    Hi Binastro I do not have exact answers for your questions, only observations. Does the Nikon 8x20 XL have a distortion free eyepiece? I am not aware of any optics that are distortion/aberration free. The aberrations may not be measurable with the equipment at hand though. Eyepieces in general...
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