Lyrid meteor shower

Discussion in 'SJ7 Star' started by RBEmerson, Apr 21, 2018.

  1. RBEmerson

    RBEmerson Humbled by events

    Joined:
    Jun 9, 2017
    Messages:
    1,095
    Likes Received:
    268
    Trophy Points:
    103
    Gender:
    Male
    Location:
    SE PA USA
    This weekend, the Lyrid meteor shower is supposed to be at its best, in the US, early in the of Sunday, 22 April.

    Google on " lyrid meteor shower 2018 " and add your country''s name to get the best timing for your location.

    As an experiment, I'm going to set my SJ7 on a tripod aimed to the northeast. I'll start it around midnight and... who knows what I'll find. I still haven't decided whether to shoot 4K or something less. The challenge is to be sure that whatever I shoot will fit in a 128 Gb SD. Regardless of the resolution, I'll use 30 fps, partly to conserve SD space, but, more importantly, to improve the exposure time.
     
  2. Sulev Svilponis

    Sulev Svilponis Elite

    Joined:
    Aug 11, 2017
    Messages:
    551
    Likes Received:
    117
    Trophy Points:
    43
    Gender:
    Male
    For proper recording of the meteor shower you need much higher ISO (by at least 3...4 stops, better 5 or more stops), than SJ7 could possibly offer.
    Increasing the exposure time has no big effect, because meteors are pretty fast, you will only make background stars brighter and it would be even harder to notice any meteors from the video.
    Good luck, anyway!
     
  3. RBEmerson

    RBEmerson Humbled by events

    Joined:
    Jun 9, 2017
    Messages:
    1,095
    Likes Received:
    268
    Trophy Points:
    103
    Gender:
    Male
    Location:
    SE PA USA
    It's an experiment. If it works, yea. If it doesn't, now I know...
     
  4. corallino

    corallino New Member

    Joined:
    Jul 31, 2017
    Messages:
    29
    Likes Received:
    4
    Trophy Points:
    3
    Gender:
    Male
    Occupation:
    Capitano di macchina
    Location:
    Torre del Greco-Italia
    I understand that it is useless to change the ISO or E.V values. in night shots, at least for what I have seen with my experiences with SJ 7.
     
  5. RBEmerson

    RBEmerson Humbled by events

    Joined:
    Jun 9, 2017
    Messages:
    1,095
    Likes Received:
    268
    Trophy Points:
    103
    Gender:
    Male
    Location:
    SE PA USA
    Agreed. Those settings apply only in the photo modes.

    Last night I set out my Hero5 Black. Nothing came along and ate it, so I'll try the SJ7 tonight. [/ wink & grin ]

    The results were a dead loss. The H5B didn't even see the glare from the lights at the end of our garage. (They're motion sensitive - no motion, no light) Nothing reflected from the trees, nothing. Regrettably the sky around here is increasingly polluted with "all night long" lights from neighbors. And the expanded "correctional facility", 4-5 miles away, doesn't improve things. The point being there's relatively a lot of ambient light. The H5B didn't see any of it. It caught the start of sunrise and that was it.

    I was surprised by the amount of noise from the camera. I can't tell how much of that is internal shot noise ("static") from gain being run full up, and how much of that is general noise. I heard a couple of cars in the videos I sampled (no desire to watch a black screen for 5 1/2 hours). The birds' "dawn chorus" was in there, too.

    Tonight I'll see what the SJ7 does. Can't be any worse. [/ grin ]
     
  6. Sulev Svilponis

    Sulev Svilponis Elite

    Joined:
    Aug 11, 2017
    Messages:
    551
    Likes Received:
    117
    Trophy Points:
    43
    Gender:
    Male
    If the (faulty or limited) FW does not allow to set ISO manually, that does not mean, that the ISO value is meaningless for video. The sensor has its supported ISO range, what camera can use, and for SJ7 it is way too narrow (low) for shooting meteors.

    See settings from this video:
    Camera: Sony α7S
    Lens: SIGMA 20mm F1.4 DG HSM | Art (at F1.4) (SJ7 original lens has max F= 2.5, this is 1.67 stops less light)
    ISO: 204,800 (SJ7 has max ISO value 1600, this is 128 times = 7 full stops less)
    Altogether, SJ7 collects 8.67 stops = more than 200 times less light, than this Sony camera in the video above.
     
    Last edited: Apr 22, 2018
    corallino likes this.
  7. RBEmerson

    RBEmerson Humbled by events

    Joined:
    Jun 9, 2017
    Messages:
    1,095
    Likes Received:
    268
    Trophy Points:
    103
    Gender:
    Male
    Location:
    SE PA USA
    Sigh... yet again... ISO, etc. settings are only for photography (still imagery).

    If any of that applies to video imagery, nobody from SJCam has confirmed that. 'Course, of late, they haven't confirmed anything... Grrrrrr
     
  8. RBEmerson

    RBEmerson Humbled by events

    Joined:
    Jun 9, 2017
    Messages:
    1,095
    Likes Received:
    268
    Trophy Points:
    103
    Gender:
    Male
    Location:
    SE PA USA
    The few samples of different videos I watched miss an important point. The various showers take their names from the constellation the shower's radiant is in. The Lyriads appear to originate in Lyra (the lyre). Rather than looking at the radiant, the cameras are looking a way from the radiant, meaning they're missing much of the show.

    The best time to look for meteors is after local midnight. The radiant point (actually it's an illusion created by perspective) is where the Earth is rushing directly into the dust left by the passage of a comet. The higher in the sky the radiant point is, better the show.

    The show is created when amazingly small bits of dust to maybe something size of a grain of sand plows into the Earth's atmosphere at an extremely high speed. The object heats up and... meteor! In addition to the meteors that radiate out, occasionally "erratics" come from almost any direction. They're just odd bits of stuff that just happens to be swept up.

    Lyra just happens to have one of the brighter stars, Vega, in the sky. Right now Jupiter is also up in the night sky. It's extremely bright. Pointing a camera at it (it's in the southern part of the sky) should give a sense of the Earth's rotation. The Earth spins, the sky stands still, and there's something to video. This is one I'd do in time lapse at up to 5 seconds between exposure.

    BTW, all of this applies to the northern hemisphere. For anyone in Oz, you're out of luck for the Lyriads. Sorry. Check with a local astronomy club for chances to see meteor showers in your sky.
     
  9. Sulev Svilponis

    Sulev Svilponis Elite

    Joined:
    Aug 11, 2017
    Messages:
    551
    Likes Received:
    117
    Trophy Points:
    43
    Gender:
    Male
    Sigh, sigh, sigh, sigh, sigh, sigh, sigh, sigh, sigh, sigh, sigh, sigh, sigh, sigh, sigh...
    I have some dedicated camcorders (Panasonic), that have ISO setting, although no photo mode at all. So stop denying ISO as a video setting. If those primitive SJCAM action cameras do not support manual ISO settings for Video, it does not mean, that ISO is not used for video. Your camera cranks its ISO automatically up, when shooting night sky, therefore you got lot's of noise on your meteor video.

    BTW, radiant is not the point, where there is most meteors. This is virtual point in the sky from where most of the meteors seem to fly away in every direction. But it is random how far from this radiant and which direction meteors appear. If you have a lens that covers most of the sky, then it is wise to direct it to the radiant. But if the lens is narrower, then there is no point to direct it to the radiant. Then it is wise to direct it where the light pollution is lowest or where the camera captures beautiful scenary as a background for the meteor shower.
     
  10. RBEmerson

    RBEmerson Humbled by events

    Joined:
    Jun 9, 2017
    Messages:
    1,095
    Likes Received:
    268
    Trophy Points:
    103
    Gender:
    Male
    Location:
    SE PA USA
    Astronomy lesson. Comets leave trails of dust behind in their trip around the Sun. In its trip around the Sun, the Earth crosses some of these dust trails. When crossing a dust stream happens, more meteors show up (every night there are a few we can see). Some of the crossings are predictable (like the Lyrids). The Perseids, showing up on 12-13 August this year, can be exciting, with a number of bright meteors in the course of an hour. Some showers don't have as many meteors and they may not be so bright. On rare occasions, the dust stream can be so thick that the many meteors look like it's raining shooting stars. That's rare, but when it happens, it's once in a lifetime event.

    Because the Earth is moving through a stream of dust, perspective creates the illusion that the meteors seem to originate from some spot in the sky. Think about driving down a straight road with tall pine trees on either side. In the distance, the trees and road merge together into a small dot. But, of course, they're really on a straight road with the edges of the road, and the rows of trees, parallel to each other.

    Moving from a straight road, to meteors in the sky... If a line following, backwards along the path of a meteor is put on a map of the sky, and that's done for every meteor seen, the lines will converge towards one patch of the sky. It's exactly the same thing as the straight road getting smaller and smaller. The constellation in the part of the sky were the lines converge, the radiant, gives the shower its name. If the radiant is in the constellation Perseus, the shower is the Perseids.

    Most meteors won't come directly from the radiant, but draw a line back along the path, and there it is. Some sky charts in newspapers, web sites, etc. will draw something like a flower, petals coming out from... the radiant.

    Looking low on the horizon isn't a good idea. The line of sight is through more of the atmosphere than looking overhead. Low on the horizon means looking through a longer, diagonal path. Looking straight up is the shortest, and clearest path. Remember how the Moon and Sun look when they're setting or rising. The reddish color and sort of "squished" look is created by looking through much more of the atmosphere than overhead. Add in air pollution, and things get even redder. Nice for sunsets, not so good for meteor hunting.

    One last item. If it's zipping across the sky, it's a meteor. If it lands on the ground, it's a meteorite. What are the chances of being hit by a meteor? The odds of winning the lottery are much, much greater. But it has happened. The result? A big bruise.
     
    corallino likes this.
  11. RBEmerson

    RBEmerson Humbled by events

    Joined:
    Jun 9, 2017
    Messages:
    1,095
    Likes Received:
    268
    Trophy Points:
    103
    Gender:
    Male
    Location:
    SE PA USA
    Results from the experiment? Nothing but lots of black screen. Even brilliant Jupiter didn't shine through. Oh well.
     
    Damian Holt and corallino like this.

Share This Page