Video cameras and UFOs

[Kiwi]

I've been checking out some so-called UFO sightings in 2009 that, as far as I can tell, are in many cases the usual ones of Venus and Jupiter, particularly back when Jupiter was at opposition and therefore at its brightest around August 2009.

While I know a fair bit about still cameras and photographs, I know little about movie cameras and even less about video cameras, and would like to know what exactly can be expected when someone turns an amateur video camera on Venus and Jupiter in dark sky.

A few comments I've seen say that without the camera's zoom being changed, the size of the "UFOs" change and that they pulsate periodically and their colour changes. Could these effects be caused by an automatic camera changing itself because of the oddball subject, a small bright light in dark sky?

I imagine that at least some of the comments about the UFOs darting around the sky are due to good old-fashioned camera-shake.

Does anyone have links to websites that show examples of what video cameras can produce under such circumstances? I've Googled the subject, but the term UFO produces hits for a hell of a lot of crank websites! I'm interested in any sites by debunkers or video techies who show exactly what the cameras do with such subjects.

Many years ago there was a bit of a flap over one particular "UFO" caught on movie film, but someone later showed that the same effect could be produced by aiming that particular make and model of camera at any artificial light that was backed by blackness and that the camera was actually focusing on its own internal mechanism.

[chrlz]

Feb 17, 2011 6:08:26 GMT -4 Kiwi said:

I've been checking out some so-called UFO sightings

I have to ask.. why?

BTW, I'm a long time lurker hereabouts, and couldn't resist this one - just registered specially! Kiwi - love your work!

While I know a fair bit about still cameras and photographs, I know little about movie cameras and even less about video cameras, and would like to know what exactly can be expected when someone turns an amateur video camera on Venus and Jupiter in dark sky.

I'm a bit more into still images too, but I think I may be able to help, and I know this guy who has posted some stuff on utube..

A few comments I've seen say that without the camera's zoom being changed, the size of the "UFOs" change and that they pulsate periodically and their colour changes. Could these effects be caused by an automatic camera changing itself because of the oddball subject, a small bright light in dark sky?

Absolutely positively they can and do!

First up, some of the colour and wavering is often due to atmospherics - when objects are low to the horizon and the air is 'unsteady' (which is often, and particularly when there is a body of water in the mix), the effects can be marked.

Then, there are all of the following issues:

1. Bokeh
When an object goes out of focus, it gets bigger. The appearance of the blob (which is NOT usable data) is called 'bokeh'. Anything that is even slightly out of focus, will contain false bokeh detail. BTW, changing the zoom, even slightly, will require re-focusing.

2. Blooming
A bright point light source, on a camera that is adjusted for normal night viewing, will be significantly over-exposed and will 'bloom' outwards so it appears larger than they really are. So, Venus or Jupiter will not appear real size or shape unless they are properly exposed. Unless the user has manual exposure controls, and knows how to use them, it will be bloomed..

and here's where it really gets started:

3. Autofocus
DOESN'T work on small point sources! The AF on all (affordable) cameras relies on contrast detection, and that requires a decent number of pixels of contrasty detail - stars and planets do not fall into that category. Most cameras use a 'feedback' loop, and the camera will rack the lens back and forth, trying to achieve focus, and very likely failing. Some cameras will simply give up after several attempts, or just keep on doing it. Interestingly, many cameras have manual focus, so you have to ask how competent is the user?

4. Exposure
As mentioned above, the camera is likely struggling to get enough light, but complicating that is the tiny bright spot - when it lands directly over what may be multiple exposure sensing points, the camera may again bounce the exposure up and down. Which adds to the blooming effect above, and also may introduce an aperture change. See next..

5. Aperture
Many of these cameras use very crude apertures to restrict the light, shaped as triangles, squares, hemispheres, even unsymmetrical polygons. If the object is bloomed or even slightly out of focus, it will take on aspects of the aperture shape... What's more, the shape may change quite substantially as the camera adjusts the exposure.

6. White Balance
Most cameras adjust white balance on the fly as well, so yes, its choice may affect the colours. However it doesn't usually adjust rapidly, so it would not normally cause fluctuations as you describe - they are more likely atmospheric issues, with the possible addition of refractive effects, and chromatic aberrations (CA) and/or the dreaded 'purple fringing'.


All in all, the effects work great to impress the gullible! To image these objects properly, you need:

1. Manual focus (and the ability to use it)

2. Manual exposure (and... " )

3. A tripod (one that costs more than $50.., and get your hands off it while filming..) (double entendre intended)

Does anyone have links to websites that show examples of what video cameras can produce under such circumstances?

As said, there's this guy I know very well... Try here:

(hope I'm allowed to self-youtube-link as a newbie..)

- not very professional, done using a very ordinary camcorder - and NO sound, sorry, just read the captions... There are 4 videos in that little series, and I think all of the above points are covered in them. Sadly my cam only has a boringly round aperture with a slightly squared off edge at the right angle...

There are probably better ones, but that's my contribution.

Hope that helps...

(edited to add forgotten red text)

[Kiwi]

Feb 18, 2011 4:58:58 GMT -4 chrlz said:

Feb 17, 2011 6:08:26 GMT -4 Kiwi said:

I've been checking out some so-called UFO sightings

I have to ask.. why?

So I can tell them what their "UFOs" really are, although I don't expect them to believe me and I do expect that some of them won't like me. One guy said that his UFO appeared about 3:30am and stayed until the sky lightened around sunrise. I checked in my planetarium program and found that Venus was rising in his area around 3:36am and was actually bright enough to be a naked-eye sight in blue sky right through until it dropped to about 20 degrees elevation in the afternoon, before setting.

Many thanks for your information -- it confirms what I suspected about video cameras. So the pulsating size-changes and colour-changes of the "UFO" are actually the camera itself trying to make sense of what it sees. Is the camera operator likely to hear or feel it making those adjustments if the environment is quiet and still enough?

Unfortunately I can't look at your video because I'm on super-slow rural dialup, but hope to be on broadband within a few weeks. Can you post any stills somewhere?

It occurred to me earlier today that the UFOlogy world needs its own equivalent of Clavius.

[twik]

Feb 18, 2011 7:36:31 GMT -4 Kiwi said:

Is the camera operator likely to hear or feel it making those adjustments if the environment is quiet and still enough?

Possibly - but I think that if someone really believes that he's capturing that elusive proof of UFOs, he's likely to miss any camera noise, or dismiss it before it even registers consciously.

[chrlz]

Feb 18, 2011 7:36:31 GMT -4 Kiwi said:

Feb 18, 2011 4:58:58 GMT -4 chrlz said:

I have to ask.. why?

So I can tell them what their "UFOs" really are, although I don't expect them to believe me and I do expect that some of them won't like me.

You nailed it! If you hang around places like Youtube, there is an endless supply of ridiculous vids, and a seemingly endless supply of idiots cheering the suppliers on (although it may just be a small team of trolls...)

One guy said that his UFO appeared about 3:30am and stayed until the sky lightened around sunrise. I checked in my planetarium program and found that Venus was rising in his area around 3:36am and was actually bright enough to be a naked-eye sight in blue sky right through until it dropped to about 20 degrees elevation in the afternoon, before setting.

That's a good example - they often shoot themselves in the foot. I've found one way to deal with them is to firstly ask - when and where was this, and was the sky clear? (give them a little rope first..) {then a quick look at Stellarium..}- ok, so you must have ALSO seen venus/jupiter/whatever - where was your object in relation to them? And can you show me some footage/images you have taken of venus/jupiter/whatever so we can compare?

Things tend to go very quiet, or the abuse begins, at that point!

Many thanks for your information -- it confirms what I suspected about video cameras. So the pulsating size-changes and colour-changes of the "UFO" are actually the camera itself trying to make sense of what it sees. Is the camera operator likely to hear or feel it making those adjustments if the environment is quiet and still enough?

As twik said - maybe. Depends on the camera and the savviness of the user - the cheaper models do tend to make audible motor noises as they rack the focus back and forth, or tiny clicks as they swap the aperture around. More expensive cameras may be completely silent.

But the thing is, an experienced user will *see* all these effects on, say, streetlights.. Again, a good test is to ask them to use the same camera and go film some known small point objects, like distant street/flood-lamps. The serious observer will bend over backwards to comply, the pretender will not go down those paths.

Unfortunately I can't look at your video because I'm on super-slow rural dialup, but hope to be on broadband within a few weeks. Can you post any stills somewhere?

Well, I could, but they aren't going to show much - it's how the process happens that is important. If it's any consolation, they are quite short and small videos, especially that first one..

And there's another complication - I'm just completely re-organising my online presence, and swapping providers... so now's not a good time!

It occurred to me earlier today that the UFOlogy world needs its own equivalent of Clavius.

Not that I would claim to be a Jay.. but I am hoping to do just that! - it's come up at a number of forums, and I have collected and drafted quite a bit of material already. But realistically, it's probably 6mo away at the moment.. I'm doing a series on Apollo radiation first, as it's a bit of a pet subject...