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  1. Mick West

    Mick West Administrator Staff Member


    Source: https://www.youtube.com/watch?v=N0GI20nAb40


    The Nikon P900 is a great camera, with an 83x optical zoom it can take amazing photos and videos of the moon. However it has a bit of a failing when trying to take photos (or video) of small bright objects, like stars, or especially like Venus. Have a search for video of Venus taken with a P900, and you will see a lot of stuff like this:

    P900 Bokeh venus search results.

    These are not images of Venus, they are images of bokeh - any out-of-focus small light will give the same effect. The problem is simply that the P900 cannot focus on a small point light source. So what we are seeing is Venus blurred and out of focus. And since it's essentially a point light source it forms an "orb" shape, commonly referred to as Bokeh. It's fairly easy to duplicate, which is what I do in the above video.

    The orb effect gets more interesting when viewed through a ripply atmosphere. The out-of-focus bokeh magnifies the effects of the ripples (because it's essentially magnifying a point light), and you get some very odd looking waves moving over the orb.

    Many people have misinterpreted these "rippling orb" videos as actual footage of Venus, but as the video above shows, it's not.

    The effect was duplicated in my garage using a bright light behind some cardboard with a pinhole in it:
    20170104-113657-ego5u.

    This was at one end of my garage, at the other is the camera, and I held a small tealight candle a few feet in front of the camera to create the turbulence. This is similar to atmospheric turbulence (from rising warm air, especially at dusk) but on a smaller scale.

    20170104-113847-cedxq.


    And the result is the same type of rippling orb we see in the "Venus" videos
    P900-Bokeh-Ripple-Loop.
     
    Last edited: Jan 4, 2017
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  2. ki_cz

    ki_cz Member

    Is it possible to 'pre-focus' the P900 to infinity to get clear shots of Venus? At certain times during it's cycle I can get clear shots of its phases with a 400mm + 1.4x extender on a Canon 5D2. From what I've seen of the P900, the zoom exceeds that, but I'm not sure if the quality is high enough at the higher end of the zoom to be able to capture a Venetian crescent?

    Probably unfortunately a little over a month before the crescent will be easier to photograph, it's in its gibbous phase at the moment.
     
  3. Mick West

    Mick West Administrator Staff Member

    There is a manual focus mode, but it's a bit fiddly. However you can trigger auto-focus in manual focus mode - essentially locking in the correct focus. So you can focus on the moon, and then take pics of Venus.

    I'll try to demonstrate this at some point, but we are under cloud right now.
     
  4. Mick West

    Mick West Administrator Staff Member

  5. Trailspotter

    Trailspotter Senior Member

    I took advantage of the Moon and Venus being close in the sky two days ago:
    IMG_9503.JPG
    By zooming and focusing on the Moon and then moving to Venus while holding focus I got this:
    IMG_9506.JPG
    Cropped image:
    IMG_9506c.JPG

    PS The images were taken with Canon SX60 HS with one of Venus alone being at the full optical zoom (65x).
     
    Last edited: Jan 4, 2017
  6. Mick West

    Mick West Administrator Staff Member

    You could probably reduce your exposure down quite a bit there and get a sharper image.
     
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  7. Z.W. Wolf

    Z.W. Wolf Senior Member

    Notes on the zoom lenses on these little digital cameras:

    - The "X" proudly written on the lens does not denote magnification power as it would with a telescope. It denotes the zoom factor range, which is the difference between the minimum focal length and the maximum focal length. The P900 for instance has a minimum focal length of 24mm (wide angle) and a maximum focal length of 2,000mm. Divide 2,000 by 24 and you get 83(.333...). A 2,000mm lens would give (roughly) 40x magnification. So that's the real "power" of a P900 lens at full zoom. It might be a little more or a little less depending on factors I don't know much about. You have to look at the "lens magnification spec." to tell for sure; and I can't find it for this camera.

    - The stated focal length of these lenses is not their actual value. They are actually shorter. The sensors in these cameras are smaller than the surface of a 35mm film frame, so you get more magnification from a given focal length. But when these cameras first came out people were much more most used to the old 35mm cameras and the effect you'd get with a given focal length, so makers simply converted the true focal length to what the equivalent 35mm film camera focal length would be.

    -It's obvious that the FE believers who use these cameras confuse magnification with resolution. So they think they have a powerful instrument in their hands - a rival of telescopes used by astronomers. But these are small aperture lenses with pretty poor resolution.
     
    Last edited: Jan 4, 2017
  8. Z.W. Wolf

    Z.W. Wolf Senior Member

    I posted this in a previous thread:

    I think that most of the scintillation in this video is caused by the photographer's breath. He was shooting through a window and his breath was hitting the glass. Look particularly at 4:20 when he makes an exclamation. The image dances at exactly the same time. Human breath is warm and turbulent, which leads to these refraction effects.

     
    Last edited: Jan 4, 2017
  9. Mick West

    Mick West Administrator Staff Member

    They are however better than most cameras the average person is likely to encounter. I've also got a Canon 7D with a 500mm lens, costing over $3,000 and weighing seven pounds. The P900 takes better photos at full zoom, and is much easier to carry around.

    No, you are not going to get very good photos of Venus with a P900. But you can at least get photos that (roughly) show the crescent, you can get photos of the moons of jupiter, you can get photos that show the general shape of the ISS, and you can get photos of distant islands and buildings half-obscured by the curvature of the Earth, and you can get some nice close-ups of planes and contrails. While it has many failings, and is not a telescope, it's a large step above the majority of cameras for magnification, and should not be dismissed.
     
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  10. Mick West

    Mick West Administrator Staff Member

    That seems correct, as atmospheric turbulence would be constant. Also the white light indicates that if this is Venus then it's fairly high in the sky, reducing turbulence.

    In other videos you do get the constant atmospheric turbulence, often accompanied by a more orange Venus. It's also more rapid than the local turbulence.

    Source: https://www.youtube.com/watch?v=wVzttz5dyJ8


    This one seems somewhat inbetween:

    Source: https://www.youtube.com/watch?v=lDbwBqGgI2Y
     
  11. Z.W. Wolf

    Z.W. Wolf Senior Member

    Oops.

    zoom range factor
     
  12. Mick West

    Mick West Administrator Staff Member

    My P900 image of venus:
    20170105-180238-boxgm.

    Relative size in the photo:
    20170105-180323-bst75.

    Technique for P900:

    Set camera to M, 1/1000, F/8, ISO 100. Venus is very bright, kind of like clouds in the sun, so the exposure is similar.

    ISO is set in the menu, under "ISO Sensitivity", set to 100
    20170517-095303-kjqgb.

    Set focusing to MF, and with the focusing screen up, point it at the moon, and press right to focus. You should get focus peak dots on the moon to show it is in focus.
    20170105-181123-2lr6t.

    Press OK to lock in the focus.
    Zoom out, point at Venus, zoom in. Digital zoom optional, but does not seem to help much.

    20170106-065011-1uw0d.

    Take the shot. If on a tripod use a remote release or timer, but it's at 1/1000th so handheld should work.
     
    Last edited: May 17, 2017
  13. Mick West

    Mick West Administrator Staff Member

    Any detail you are seeing is imaginary though. There's a lot of frame-to-frame variation from the atmosphere (Earth's). Here's two shots less than a second apart.
    20170105-183022-ucrww.

    These were handheld, 1/2000th, F6.5
     
    Last edited: Jan 6, 2017
  14. ki_cz

    ki_cz Member

    wow, more detail than I was expecting. The P900 continues to impress, thanks for sharing.
     
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  15. Mick West

    Mick West Administrator Staff Member

    The P900 actually says "Equiv. 135" on the barrel:
    20170106-070156-zjz1h.

    Most compact and bridge cameras do not, it's mostly of interest in the mega-zoom category.

    Why "135" and not "35mm"? 135 is the name of a format of film that's 35mm high, the "35mm" isn't actually the frame or sensor size, which is 24mm high (and 36mm wide, with a photo every 38mm). So saying 135 is better than 35mm as the 35mm is not an actual relevant dimension in the absence of physical film.
    [​IMG]
     
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  16. Z.W. Wolf

    Z.W. Wolf Senior Member

    Are you asking why the film format is called 135? As far as I can remember the 135 designation was specific to a Kodak product: a 35mm still camera film that came in its own cassette; introduced sometime in the '30's, I think. Before that photographers had to use a bulk film loader to load it in re-usable cassettes. (I did just that when I was on a college newspaper staff, because bulk film was cheaper.) The Kodak product designation became the generic name for this kind of film over time. Much like jello or kleenex. I don't remember the term being used much. (I was a photography major in the mid '70's. Yes I'm old.)
     
    Last edited: Jan 6, 2017
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  17. Mick West

    Mick West Administrator Staff Member

    One more impressive P900 feat, a handheld photo of Jupiter showing the bands!
    20170508-074232-f7shu.
    DSCN4694.JPG

    Again I used the moon to focus. 1/160th, f/6.5, ISO 100, 2000mm. May 7th 2017 9:41PM. This was exposed for the moon with EV -0.7

    This is what Stellarium says it should look like at that time.
    20170508-075652-ab4ql.
     
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  18. Z.W. Wolf

    Z.W. Wolf Senior Member

    It looks as if the Great Red Spot is there too. With that kind of resolution you must be seeing the Galilean moons.

    Sixteen years ago, in the early days of the Internet I ran across a UFOlogist who was capturing a mysterious object over several nights with a camcorder. He ironically remarked that it had some mysterious "moons" around it. Fortunately he included the dates. The "moons" were just that of course because the mysterious object was Jupiter, and I was able to check the pattern of the moons on his videos against the expected positions of the Galilean moons, which matched.
     
    Last edited: May 9, 2017
  19. Amber Robot

    Amber Robot Member

    Not according to his Stellarium comparison. Where do you see the red spot?
     
  20. Z.W. Wolf

    Z.W. Wolf Senior Member

    Oops, you're right. I wasn't paying attention.

    Ironic since, my story about Jupiter included checking the positions of the moons at the time.
     
  21. Mick West

    Mick West Administrator Staff Member

    Several people have noticed similar problems with the P900. The following videos show techniques for photographing Venus or other celestial objects


    Source: https://www.youtube.com/watch?v=dICIKYn5w4w


    For Jupiter:

    Source: https://youtu.be/2KafnrXxcIs?t=1m15s

    Both use a trick of setting the exposure by shining a light in the lens and the using AE-Lock. That's a quick fix, but really it's better to set the aperture, shutter speed and ISO manually. People often forget about ISO.
     
  22. Mick West

    Mick West Administrator Staff Member

    An early morning photo of Venus. The consistency of the phases should really be a clue for the flat Earth folk.
    Metabunk 2018-11-20 10-34-32.
    1/2500, F/8, ISO 100, 2000mm, handheld, manual everything. Nikon P900.

    Matches Stellarium
    Metabunk 2018-11-20 10-42-35.
     
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  23. Astro

    Astro Active Member

  24. Mick West

    Mick West Administrator Staff Member

    1/2500 plus image stabilization cures most shake.

    Venus is very close to Earth right now. Very big and bright, but just a crescent. I was quite surprised it was so thin a crescent, but it makes sense:
    46510648_10156232946629514_1437315126343499776_o.
     
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