GKPE: General Ramblings thread

akiwi wrote in post #3054904
Remember I am on the other side of the world.
Look at the picture upside down!

To the right of me was the north star, but there isn't such a nice mountain range below that, and I was photographing out my door, so I didn't have that in the picture.
Anyway If I had that in the picture, the stars would be rotating around it.

I'll leave the inverted view to you!

I think the latitude has something to do with how much you see of the lower rotation.

A 10-minute exposure facing north-west has just given me a nice set of convex to straight to concave traces, including the Southern Cross. Must find me an astronomer to talk with.

somethingsimple wrote in post #3054334
hey kirst if you wanna go shooting locally give me a bell, might be able to go with (will go further afield too after this month, when i can get my car fixed)

Good idea, we should plan that soon, just not this week. I can pick you up considering you live within a 1km radius of my place


aKiwi - I love the star trail shot

CliveyBoy wrote in post #3054948
I'll leave the inverted view to you!

I think the latitude has something to do with how much you see of the lower rotation.

A 10-minute exposure facing north-west has given me a nice set of convex to straight to concave traces, including the Southern Cross. Must find me an astronomer to talk with.

Good point, It is probably a combination of Lattitude & time of year.
On the other hand, time of year shouldn't change where the centre point is, as this is determined by the earth rotation.
On the north pole it will be straight up,
on the equator you probably won't see it as it will be below the horizon, so purely lattitude will affect it's position in the sky.

Well Im back. Dam cold out Muriwai tonight. I got a 1min exposure as my longest.

weka2000 wrote in post #3054974
Well Im back. Dam cold out Muriwai tonight. I got a 1min exposure as my longest.

I am interested in seeing that

happy lated birthday Kirst.

Nice photos tony and wazza.

forsaken wrote in post #3055054
Nice photos tony and wazza.

Thirded. And Akiwis Star trails. Here's my attempt from Tekapo last week. Half hour exposure but alas I don't have a flash, let alone a half hour one!!

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CliveyBoy wrote in post #3054892
I am accustomed to seeing star arcs as convex, not concave, but i have probably only tried one aspect. I am intrigued by the circumstances required to obtain a convex path relative to the camera.

i might have completely misunderstood you, but doesn't the direction of the trail depend entirely on the camera's position on earth and direction it points at the sky relative to the celestial north or south pole (depending on hemisphere of locale) ?

tag141 wrote in post #3055071
Thirded. And Akiwis Star trails. Here's my attempt from Tekapo last week. Half hour exposure but alas I don't have a flash, let alone a half hour one!!


Dam ambient light from the tents.

Still pretty good.
I guess one of my advantages was being in the mountains where the air is pretty clear, no large towns anywhere near and no moon.

somethingsimple wrote in post #3055073
i might have completely misunderstood you, but doesn't the direction of the trail depend entirely on the camera's position on earth and direction it points at the sky relative to the celestial north or south pole (depending on hemisphere of locale) ?

Eggxaktlie!
Pointing Exactly North in the northern hemisphere, or South in the South will get the arc in the middle of the picture.
Then the curves will be concave, or curved down.
Looking in the other direction, (South in the north, or North in the South) will produce convex or upward curving streaks.

simply put, the closer to the north (or south) axis that you point the camera (equatorial regions would have to make do because either axis is below the horizon for them),the more circular the star pattern will be

lucky northerners have the Pole Star but we have a significant 'empty' patch of space which can only be pinpointed by a fiddly trianglation of the Pointers and something else which escapes me presently: but anyhow, the rest of the stars will appear to rotate around either of these 2 central points, therefore the further away from either that you point the camera, the longer and more 'straight' the star trails will be (sections of circumferences of wider and wider rotations)

woops, i said it was going to be simply put LOL

http://solar.physics.m​ontana.edu …s/Sundials/skyd​ome_S.html

for anyone down our way who wants to get circle star trails, all you need is a compass and a sextant...

and a camera...

or a ruler... The first step is to locate the Southern Cross (Crux). Once you’ve done this, you need to draw an imaginary line along the longest arm of the Southern Cross about 4.5 times the length of this arm. This takes you right to the celestial South Pole.

wikipedia says this: [edit] Method one: The Southern Cross
The Southern Cross, together with the two pointer stars α Centauri and β Centauri will help to find South if you draw an imaginary line from γ Crucis through to α Crucis (these are the two stars at the extreme ends of the long axis of the cross), and follow this line through the sky. Of course, you have to know when to stop. Either go four and a half times the distance of the long axis in the direction the narrow end of the cross points, or, join the two pointer stars with a line, divide this line in half, then at right angles draw another imaginary line through the sky until it meets the line from the Southern Cross. This point is the South Celestial Pole. It should be noted that the South Celestial Pole can be found in the dim constellation Octans, the Octant. Sigma Octantis, is identified as the South Pole Star, over a degree away from the pole, but with a magnitude of 5.5, it's barely visible on a clear night.


[edit] Method two: Canopus and Achernar
The second method uses Canopus (the second brightest star in the sky) and Achernar. Make a large equilateral triangle using these stars for two of the corners. The third imaginary corner will be the South Celestial Pole.


[edit] Method three: The Magellanic Clouds
The third method is best for a moonless and cloudless night as it uses two faint 'clouds' in the southern sky. These are marked in astronomy books as Large and Small Magellanic Clouds. They are described as white birds both by westerners as swans, and by Aboriginals as brolgas. These 'clouds' are actually galaxies close to our own Milky Way. Make an equilateral triangle, the third point of which is the South Celestial Pole.

LOL this is getting harder and harder with every helpful guide

tag141 wrote in post #3055071
Thirded. And Akiwis Star trails. Here's my attempt from Tekapo last week. Half hour exposure but alas I don't have a flash, let alone a half hour one!!

| Byte size: ZERO | Content warning: NOT AN IMAGE

Dam ambient light from the tents.

you know I am worried that doing a long exposure might damage the sensor, over heating and stuff

nice picture tho

forsaken wrote in post #3055054
happy lated birthday Kirst.

Thankies, Si

tag141 wrote in post #3055071
Thirded. And Akiwis Star trails. Here's my attempt from Tekapo last week. Half hour exposure but alas I don't have a flash, let alone a half hour one!!

~image here~

Dam ambient light from the tents.

I keep thinking these are rain drops, and wondering why anyone would have their camera outside in a downpour (yours included akiwi). I realy should read the text instead of just looking at the pictures

Nice image

theflyingkiwi wrote in post #3055103
you know I am worried that doing a long exposure might damage the sensor, over heating and stuff

but it's going to be at night, so sensor will be cooler. I've left the shutter open for two hours before with no problem (on the 10D).

It eas below freezing when I took mine.