Star trail help!!

jonathan_ed

jonathan_ed

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Jonathan
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I've had my first go at star trails and i feel i may need a bit of help.

I did a few hundred jpeg images, at f/5.6 with an exposure time of 30 seconds for each exposure.

I have then put these photos in a stacking software from startrails.de

I'm not happy with the results, its not the composition its self as i know thats poor and needs work. Its that the stars are looking like little blobs with very slight gaps between them on the trail. I was hoping for a seamless line. Is this a software problem, or is it something to do with the actual photos taken.... Help!

I have attached the photo below!


a>


Thanks in advance
 
If you did have time gaps then you see gaps between the stars...

Personally, I don't like the idea of taking thousands of photos and killing your camera in a few days like that. A remote and a proper long exposure of a couple hours sounds more like a way forward. And you definitely need to shoot RAW to compensate for dark and very bright patches of the sky and retain all the colour information. JPEG is wasteful, and this is where it hurts most.

Having said that, you need fresh battery, clean sky, no city lights, warm tea, and something to do for all this time. This is no easy game and so far it has defeated me...

My best go so far (prematurelly killed off by the rain clouds coming in):
4819027963
http://www.flickr.com/photos/daugirdas/4819027963/
4819027963
 
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I don't use jpeg usually, i always shoot in RAW, but everything i have heard and read says do it in Jpegs

Well i took the photos in the middle of no where in France, so there was no light polution. To do i with RAW would mean id be processing a few hundred shots.

Battery power isnt an issue.

I don't fancy one long exposure as i heard it can just generate loads of heat and damage the sensor.
The etchnique i went for was contiunal shooting with 30 second exposures, ISO1000
 
Problem with a single long exposure of several hours is noise....

I have done several startrails using 30 second exposures... from 1 hour to 3 hours... which is only 360 shots for 3 hours...

and here is the result with startrails software...

http://www.flickr.com/photos/etunar/3903939153/in/set-72157622085150244/

looking at your image, it looks like a software issue.... could it be that u might be using a wrong setting?
 
I seriously doubt that it's a software issue! How were you taking the shots?

I would suspect that you have a delay between shots! The simplest way is to set the camera to continuous shooting with an exposure of 30 seconds then simply lock the shutter. also ensure that noise reduction is switched off!
 
oh, existent, i forgot to ask, which software dod you use?

as for settings of the software, i couldn't tell you. there doesn't look to be too many settings but it is all in german for some reason, even when you click on the english language
 
I agree with Steve... looks like a time gap, something like mirror lockup and self timer to trigger the mirror to lift.
 
This is going to sound strange now.
I have just looked at some pictures my dad took at Hastings Sea world place.

They were not aloud to use flash so he just put the camera onto sport mode, the fish have come out blurry but what is interesting is that the light bouncing off the fish, (pin lighting from the tanks) looks exactly the same as your start, broken up into equal lengths even though its a trail.

I'm really quite interested to find out what this is now.
 
Can you post a single shot with the exif data ? also at what focal length were the shots taken?
 
I've had this problem before.
The time gap between each frame is usually down to the camera taking it's time processing the shot with noise reduction and how long it takes the buffer to empty before taking the next shot.
I would doubt it's due to the software.
 
orac said:
I've had this problem before.
The time gap between each frame is usually down to the camera taking it's time processing the shot with noise reduction and how long it takes the buffer to empty before taking the next shot.
I would doubt it's due to the software.
Click to expand...

Good point. Can't speak for your camera but mine says it takes as long to process as the exposure was i.e a 30sec exposure would take 30sec to process so you would get a 30sec gap. Mine is only a poxy entry level DSLR but I would read your manual to check.
 
Hmmm. I don't think mirror lock up was on and can't comment on noise reduction, will look into that one.

As for exif data, for sone reason I can't post a photo on here today, don't know why. But it was at 20mm focal length.

Oh and ny camera is a 40d if that is of any use....
 
orac said:
I've had this problem before.
The time gap between each frame is usually down to the camera taking it's time processing the shot with noise reduction and how long it takes the buffer to empty before taking the next shot.
I would doubt it's due to the software.
Click to expand...

I think that's about it.

There is a feature on some cameras, Long Exposure Noise Reduction; basically what this does, once a picture of, say, 30 seconds, is done the camera will then take another picture of same duration.

In effect, with this feature on, you'll get less noise but a 30" exposure will turn into two 30" exposure, only one of which you'll ever see & have use of.
 
If that's what the cause is, yes... The camera won't then take a dark frame and subtract it from the image. I think the default is on for shots over 1 second... It was one of the first options I turned off...
 
I agree with Orac and concur with John's analysis. It looks as if you had noise reduction switched on, which is a killer when trying to do star trails with multiple exposures.
 
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