Star trails - how to achieve smooth trails?

[niko]

Hi all,

went I used to take star trails with my trusty film camera I got nice smooth trails now when I use my DSLR I have two problems - hoping someone can comment.

If I leave the lens open for a long time too much stray light seems to come in and lighten the image too much. So, I have taken a series of shots and then stacjed using Startrails.exe - the problem here is that the trails are not smooth but a series "blips" as the lens has to close at some point between shots.

Is there a way to get the nice smooth trails I was getting with the film camera on a dslr?

thanks gang

niko

[bmitchell82]

use the program Star trails, and have as small as possible delay between your shots.

eg, hold open for 2 minutes, and download within 2-5 seconds and open up again. the movement within this time frame isn't noticeable enough for blips

[midnight]

Niko,

As star trails didn't involve setting up telescopes, it was one of my first photos from my first ever (and only) DSLR. I have a 40d and wished I had one of those timer remotes at the time :mad2:.

Anyway, here is photo I took in my backyard and what I did was :

1. Point south (yep - I almost got that wrong when I got too anxious to get out and start clicking!!):screwy:
2. Use a wide angle lense - I used a Canon 16-35mm at 16mm
3. Now to your issue - yes I had the same problem. So you need longer exposures to fix this - but stray light becomes a problem. So stop down the lense and reduce the ISO. I found F8 at least to give me meaningful trails. So this photo is at F8
4. ISO - I used ISO200.
5. Each frame is 4 minutes long which helps reduce the "blips" between frames.
6. I then used the EOS utility supplied with the camera and left my laptop in the back room and ran out the USB cable to the camera.
7. Then I setup the EOS capture to do 4 minutes + 5 sec wait (it wouldn't trigger below 5 sec for some reason) and then I repeat that for 110 times (ie 110 x 4 minutes of exposure = 7.3hrs of trails)
8. I also used the AC/DC converter power supply in the battery compartment (I actually modified it to parallel it with a buck converter so I could power it off a car battery all night)
9. Go to bed :D
10. Get out of bed and hope no-one has knocked off your camera :sadeyes:
11. Run Startrails and import all your pics and I was suprised how well this program went!!

Good luck and if it's cold (like down here), you may need to put on your lense hood. I modified mine (they're only about $20 for a cheap clone) to solder a ring of small 1/2watt resistors around inside and then black heat shrink the lot for a very cheap (<$1) dew countermeasure and hook it up to 12V.

I was lucky that at midnight, somehwere in town, a glow was visible for about 20 minutes and hence shows up as a glow down the bottom. The trees are lit by the most annoying flood light across the road at the carpark :mad2:

Cheers,
Darrin...

[niko]

thanks guys - I'll have another bash (when the clouds and moon abate!)

niko

[erick]

Niko, you have in-camera-noise-reduction switched off?

[luigi]

Star Tracer:
http://www.tawbaware.com/startracer.htm
It does exactly what you need for a very fair price

[[1ponders]]

I know what you mean Niko. Even with the shortest of gaps between the images and no ICNR I still get gaps with the trails. Rather frustrating actually.

[erick]

ps. I have a few film SLR camera bodies I can sell you ;)

[luigi]

See my post! ;)

[erick]

Yes Luis, that software looks to be the solution in most circumstances.

[niko]

Thanks guys for the comments - thanks Luis that looks exactly the ticket!

Will try if ever the clouds part!

niko

[niko]

Eric,

thanks for the offer :-) Still have perfectly functioning (if somewhat dirty) Minolta SLT101b I can dust off if need be but I'm afraid the ol' eyes struggle to focus anything on the ground glass viewfinder. I did start my astrophotography with it though and when I did get something in focus was always really happy with the result. If find focussing the dslr tricky too - it goes part infinity which is very frustrating.

cheers

niko

[luigi]

If you need any help with Star Tracer you can contact me, the trial version should be fine enough to let you know if it does what you need. I have no affiliation with the software just a regular user.

[[1ponders]]

thanks for that Luis. Something new and improved to play with :D Cheers. :thumbsup: