Astrophotography newbie. Problems with lens?

sean · 19 Mar 2007 at 06:05

Hi all,

We've had a perfectly clear sky most of the night so I figured I've give astrophotography a wee go. Unfortunately, I appear to be rubbish at it :eek:

. If anyone's willing to give some advice, I have a couple of questions:

First, are there any budget tripods worth owning out there? I can't find any mentioned in the stickied threads and I've got my eye on an inexpensive Hama tripod but I'm obviously wary because of the price.

Second, I have a question about my lenses. I took a handful of shots just to get a feel for the exposure times necessary; try my hand at manually focussing stars and so on. Images from the kit lens seem fine enough if you ignore the lack of any photographic merit:

Now forgetting the wind-induced wobble ( and my need for a heftier tripod ) for a sec, all the shots from my telephoto have nasty optical artifacts in them:

edge enhanced to really show the effect:

Any suggestions what this is, some sort of lens flare? I bought the lens used and would rather think I've not been had .

Kit used:
Canon 350D
Kit lens
Canon 75-300 USM (used)
Cruddy wee mini-tripod
Remote shutter switch
edit: Everything shot at F7.1 if that makes a difference here

Cheers,

Sean

sean · 19 Mar 2007 at 06:07

A different perspective with the same telephoto lens:

edge enhanced:

unknowndomain · 19 Mar 2007 at 09:24

I dont know about the lens but for a tripod look at manfrotto's offerings.

Helium_Junkie · 19 Mar 2007 at 09:34

You said it was windy when these were shot, are you sure it wont have been that? I cant think of any other reason for it.

unknowndomain · 19 Mar 2007 at 10:13

Helium_Junkie said:
You said it was windy when these were shot, are you sure it wont have been that? I cant think of any other reason for it.

I think your right the first images look like wind moving the camera slightly however the second set are weird because the light goes right over the tree branch surley the stars arent bright enough to see that sort of thing happen?

Helium_Junkie · 19 Mar 2007 at 10:51

unknowndomain said:
the light goes right over the tree branch

If the branch is moving with the wind then the star would be recorded as moving straight over it, since at seperate times the branch would not be in the way.

sean · 20 Mar 2007 at 00:12

Helium_Junkie said:
You said it was windy when these were shot, are you sure it wont have been that? I cant think of any other reason for it.

Y'know, after looking at the pics again (and being awake this time - I shot them at 5am!) what I thought were artifacts or "ghost" stars must just be dull stars invisible to the naked eye or through the lens. Oops

I'll try again with less wind and a proper tripod.

unknowndomain · 20 Mar 2007 at 09:12

sean said:
Y'know, after looking at the pics again (and being awake this time - I shot them at 5am!) what I thought were artifacts or "ghost" stars must just be dull stars invisible to the naked eye or through the lens. Oops

I'll try again with less wind and a proper tripod.

Lol sorry thats the effect I thought you were trying to get i didnt realise you didnt want the white stripes... Clicky

Helium_Junkie · 20 Mar 2007 at 09:41

sean said:
Y'know, after looking at the pics again (and being awake this time - I shot them at 5am!) what I thought were artifacts or "ghost" stars must just be dull stars invisible to the naked eye or through the lens. Oops

I'll try again with less wind and a proper tripod.

Waaaait, you were worried about the extra stars rather than the jagged trails?
In that case, yes - a long exposure will likely pick up extra stars - close your aperture a bit to get rid.

Mobius 1 · 20 Mar 2007 at 11:11

why are the skies purple and orange? I thought night skies were meant to blue dark blue/black?

Helium_Junkie · 20 Mar 2007 at 11:17

-Tauren- said:
why are the skies purple and orange? I thought night skies were meant to blue dark blue/black?

Mine always come out reddish. As do a nearby friends. I don't know whether it's down to light pollution or camera or what :/ I usually adjust the hue to be bluer, then down the brightness/contrast until they look nicer.

As so:

Mobius 1 · 20 Mar 2007 at 11:23

Helium_Junkie said:
Mine always come out reddish. As do a nearby friends. I don't know whether it's down to light pollution or camera or what :/ I usually adjust the hue to be bluer, then down the brightness/contrast until they look nicer.

As so:

Oh yeh...in the UK you have a lot of lighting around streets etc dont you? Hm thats maybe why then. Nevermind. I've just woken up