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 (Brendan)]

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 (Darrin)]

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 .

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!!)
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
10. Get out of bed and hope no-one has knocked off your camera
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

Cheers,
Darrin...

[niko]

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

niko

[erick (Eric)]

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

[luigi]

Originally Posted by 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

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

[[1ponders] (Paul)]

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 (Eric)]

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

[luigi]

Originally Posted by [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.

See my post!

[erick (Eric)]

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]

Originally Posted by niko

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

Will try if ever the clouds part!

niko

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] (Paul)]

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