Originally posted by Superiorraw
I was wondering if there is any other way to confirm or identify what I have filmed is a passing satellite or station of some kind, because if there
is an alternative schedule for it I might be able to match it to my sighting?
Havta be honest and say I don't know for sure, but if you have the 'Heaven's Above' data, from:
you have THE data. It is recognised as the authoritative place to go for such stuff - I don't think anyone has ever questioned H-A's data and
accuracy.. I've used them quite a few times for ISS and shuttle watching, and a couple of Iridium flares. Apart from one screw up with
daylight-saving time (my error!), they were always spot on. Having said that, I haven't personally chased up historical data. NASA will have
archives of all ISS/Shuttle orbital data, but again, I haven't tried chasing this down. NASA are pretty helpful (if a bit slow to respond) to email
enquiries, as long as you ask sensible questions ..
Another question I'd like to also ask, and its regarding the footage. At the beginning some point the object appears to change colour?
red/green. Is this object changing colour or is light reflecting off it or is it the videocamera when I zoom in?
I didn't look at the bit you refer to - how about some frame grabs, if you want something specific looked at..?
But it could be either. If a bright object is reasonably distant, and the air between you and it is turbulent, dusty, misty, polluted (and of course
it often is), then you can get all sorts of colour variations. The lower to the horizon and more distant, the worse. Check out Sirius when it is low
to the horizon and you'll see what I mean - you won't believe the colours!
That's because the air is acting like hundreds of little variable prisms and refracting the light. The brighter and fuller the light spectrum
(that's why Sirius is so good at it!), the more colours you will see.
But there are ALSO all sorts of effects that can cause colour impurities in your camera system:
- chromatic aberrations - all lenses have these, and they result in reddish/bluish/purplish/greenish edges and contamination, especially around/in
high-contrast areas. Zoom lenses at telephoto, are particularly prone to it, sadly.
- 'purple- (or sometimes green) fringing' - an effect caused by incident light hitting a sensor at an oblique angle. This is often confused with
C-A and it can be hard to tell which is which. (As a side note, the Sony DSC-F828 camera suffered badly from this and/or CA, yet it was fitted with a
*superb* Carl Zeiss lens! - so good glass doesn't necessarily mean you won't see defects..)
- sensor blooming - light spills from the design of the electronics & microlenses over CCD and CMOS sensors. Again, it gets tangled up with the above
- lens/sensor design issues - some lenses/sensors do have colour casts that may reveal themselves in difficult lighting, or when struck by UV or IR
(look up the 'Leica M8' debacle)
- white balance issues - if the camera is left on 'auto' white balance, it will make up its own mind on the colours - that's a bad thing! Even
when using presets there can be inaccuracies, but when filming something of unknown colour the camera should be set to DAYLIGHT white balance if
Hope that helps, and doesn't scare you too much...