Please explain?

[silv (Annette)]

What about planes?

The upper part of the lines are the planes' actual light trail in 8 seconds. The different brightness in those upper parts are the flashing position lights.
The lower part, where the streaks are wavy, are their exhaust trails, reflecting the last of the sunlight, and after the wind has played with them.
"Having taken the shots not long after twilight ended"

If you know the exact date and time, you could look for the planes here and see whether there were 3-4 planes, maybe waiting for landing permission or taking off one after the other?
https://www.flightradar24.com/2018-1...37.71,144.86/9

It's already set to location Melbourne on Dec. 27th, 11.30 UTC, 22.30 Melbourne time.

[RyanJones]

Originally Posted by mental4astro

Oh, the camera shifted on the fence post...

"Technically " I'm still correct, the mount (ie fence) cased the camera to shift... clutching at straws here...

Thanks Ryan for the slap in the face missed that point.

All good Alexander. We’ve all done it 😄

I’m totally with you on camera movement. The only thing that is odd is that the lines aren’t all parallel. Certainly the most logical reason though

[mental4astro (Alexander)]

The reason why they are not perfectly parallel is very easy. Think of this: The camera is leaning on an angle on the post. As it slips, the camera is not only rotating, but also sliding out. This explains not just the curve, but also the change in the radius of the curve, and the difference in the curve from the left side of the picture to that of the right side. This last difference being due to the size and shape of the camera, with that part highest on the post rotating more than the far side which essentially just slid out laterally with very little rotation. The final little wobble in the trail indicates that the camera shuddered a little in the last few instances of the movement. And the brighter stars show a little jolt in their final shape as the camera thumps in its final resting spot.

Alex.

[Sunfish (Ray)]

You are suggesting a kind of double exposure?

Some long stripy lines where the camera was moved quickly at the beginning or end of the exposure , then the rest of the stars exposed for the remainder of the exposure. Makes sense. Normally I see vibration but I can see how two different movements could cause this. Moved the camera before the end of the exposure or slipped on the post as it started.

Originally Posted by mental4astro

The reason why they are not perfectly parallel is very easy. Think of this: The camera is leaning on an angle on the post. As it slips, the camera is not only rotating, but also sliding out. This explains not just the curve, but also the change in the radius of the curve, and the difference in the curve from the left side of the picture to that of the right side. This last difference being due to the size and shape of the camera, with that part highest on the post rotating more than the far side which essentially just slid out laterally with very little rotation.

Alex.

[RyanJones]

Originally Posted by mental4astro

The reason why they are not perfectly parallel is very easy. Think of this: The camera is leaning on an angle on the post. As it slips, the camera is not only rotating, but also sliding out. This explains not just the curve, but also the change in the radius of the curve, and the difference in the curve from the left side of the picture to that of the right side. This last difference being due to the size and shape of the camera, with that part highest on the post rotating more than the far side which essentially just slid out laterally with very little rotation. The final little wobble in the trail indicates that the camera shuddered a little in the last few instances of the movement. And the brighter stars show a little jolt in their final shape as the camera thumps in its final resting spot.

Alex.

If only astrophysicists could reverse engineer the time line of the universe so eloquently Alex. Makes sense.

[mental4astro (Alexander)]

Ray, most likely it happened at the start of the exposure. This because of the final shudder in the sliding action and the vibration/jolt at the end of the slide. The camera was very likely teetering a little when it was set down, and when the shutter was depressed and the camera released from Michael's grip, this was enough to cause the camera to slide, even if it was on a timer delay.

Ryan, you flatter me. Eloquent! Thank you

[Mickoid (Michael)]

Wow, you guys are really keen to explain the cause of these trails! Alexander, were you a detective in your past life? Maybe you still are, you'd give Sherlock Holmes a run for his money - that was brilliant stuff and right on the money, I'd say!

I had the camera purched on a flat fence post with another bit of timber wedged under the lens to point it higher up in the sky. What you said happened makes sense. The 2 sec shutter delay wasn't long enough to settle the movement caused by my finger on the camera and possibly shutter vibration. Consequently, the camera probably moved for a while, sliding and rotating on the wood wedged under the lens until it stopped. Teach me not to bring a tripod with me! Then again, if the shot had nothing unusual about it, it would hardly have been of much interest to anyone.

Thanks for everyone's input but the prize goes to Alexander!