my first startrails shot - need some help here

[ovizii]

after reading this article: An Introduction to Shooting Stars Trails I set out and tried to capture one of those.

The settings used were:

f3.5
30s
ISO 1600
18mm
star-filled sky in Africa, manually focused to infinity, no wind blowing, tripod rock-steady, no manual lighting of the foreground.

I took 140 shots + 1 darkframe (with lenscap on)
Using the average forground option doesn't change anything for the final image.

I mixed them up with the suggested star-trails tool and this is the result: http://i53.tinypic.com/yigba.jpg

- Does this look OK to you for the settings I used?
- Why are my star-trails so thick?
- Would it help if I showed you a sample shot before mixing?

[CBabcock]

- Does this look OK to you for the settings I used?
- Why are my star-trails so thick?
- Would it help if I showed you a sample shot before mixing?

I'm no expert, so I'll just offer my opinion.
I think it looks good. In answer to your question, I believe the trails are thick because of your high ISO. Try lowering that down and maybe stopping your aperture down a little. With a 30s exposure, you could get away with f/16 at 100 ISO.

[ovizii]

thanks.

for info only:

I used f3.5 as the author of that article recommended it. I only changed from ISO 800 to ISO 1600 as the ISO 800 shots were almost totally dark...

would love some more feedback.

[windrider86]

any chance you could post one of the photos here for us? Makes it much easier to critique of we dont have to flip back and forth

[ovizii]

Originally Posted by windrider86

any chance you could post one of the photos here for us? Makes it much easier to critique of we dont have to flip back and forth

here is the one I posted above, uploaded here. and just in case you were talking about one from the series I'll post that as well.

[ovizii]

weird, the second attachment is added to the above post but no thumbnail is showing.

[tlpphoto]

Nice image, I'm glad you you included something in the foreground as it adds some interest.

As CBabcock said, the star-trails are probably so thick because your ISO is high.

I captured some star trails a few months ago while in the desert of Arizona. You can see them in the last two images in my blog post:
Radiant View Photography Photo Blog: Saguaros, Sunrises and Star Trails

For the last image, I used 15 (fifteen) 4-minute exposures, for a total exposure of 1 hour. My camera settings were F/4, ISO 100 on a 50mm F/1.4 prime lens. During the last 4 minute exposure, I used my flashlight to light paint the Saguaros cactus. Also, I used tungsten light balance to give the blue color to the sky.

I encourage you to try again. As with most of photography, this is a niche area that takes practice.
Tim

[ovizii]

thanks. I won't be giving up, just needed a hint what to change/experiment with.

as I said: tried the same settigns as above but ISO 800 and you could hardly see any star, way too dark.
still will try again with lower ISO.

could also have tried 50mm with f1.8 but the 18mm looked great to me in that situation.
regarding your photos: how come your sky is so light? blueish almost? any city close by? I was in total wilderness, the nearest city lights 100s of km away..

any other hints?
will go try again as soon as I get a chance.

[tlpphoto]

Originally Posted by ovizii

regarding your photos: how come your sky is so light? blueish almost? any city close by? I was in total wilderness, the nearest city lights 100s of km away..

There was a city (Phoenix) nearby, but I suspect the sky has color because I started shooting this while it was still Nautical twilight (before astronomical twilight when the sky becomes totally black). When I look at the series of images I composited to built the star trails, I can see a definite change in the lightness of the sky.

Not sure what kind of camera you are using, but check to see if it has a "bulb" mode. Your images were 30 seconds, which is the longest "normal" shutter time. With bulb mode, the shutter stays open as long as you have the button pushed down. Obviously, a remote release is a must here. Most of them have a slide lock so that you can lock the remote shutter button down without actually holding it. The nicer (more expensive) ones have a timer function built in as well (which is very nice for these type of images). You can probably set your laptop up to remotely control the camera and do the same thing. At least I know Canon cameras come with this type of software.

Hope this helps.
Tim

[ovizii]

thx for the info.
I shot in total darkness.
using nikon D90, have remote, used 30sec as that was what the tutorial author advised.
will experiment.
have remote I can program. it was set to 30sec shots and infinite length, I stopped it after 140 shots though...

still unsure what to change next:

have to wait for total darkness before that I could hardly see any stars. if I lower the ISO I will have only black pics. not sure what to change next time?