Attempt at Star Trails

Dramatapix®

After seeing a post of someone elses star trails, I attempted to take one of my own this last weekend in New North Portland, Me.



I'm not sure what happened, but can someone tell me why the stars are multi-colored? I shot this at 5 minutes and f4.0 at 800 ISO. Any advice or input is welcome and appreciated.

Thanks.

mmroden

nice shot.

A few things: First, you can get more stars if you set to a more-open aperture. So at 2.8 you'll see smaller stars, f/8 only the big ones, etc. Stars can all be shot at the widest aperture because they're all infinitely away

As for why colors show up, the short answer is that when there's very little light, our color vision doesn't work but black and white vision does. A more lengthy explanation can be found here: http://www.astropix.com/HTML/I_ASTROP/I14/I14.HTM

I personally prefer longer star trail exposures, on the realm of about 15 minutes, to get real swirliness. But that might require a bit too much patience, especially if shooting with someone else nearby

Dramatapix®

mmroden wrote:

nice shot.

A few things: First, you can get more stars if you set to a more-open aperture. So at 2.8 you'll see smaller stars, f/8 only the big ones, etc. Stars can all be shot at the widest aperture because they're all infinitely away

As for why colors show up, the short answer is that when there's very little light, our color vision doesn't work but black and white vision does. A more lengthy explanation can be found here: http://www.astropix.com/HTML/I_ASTROP/I14/I14.HTM

I personally prefer longer star trail exposures, on the realm of about 15 minutes, to get real swirliness. But that might require a bit too much patience, especially if shooting with someone else nearby

Well I'll be darned, and I thought I did something wrong.

Mr. 2H2O

As for why colors show up, the short answer is that when there's very little light, our color vision doesn't work but black and white vision does. A more lengthy explanation can be found here: http://www.astropix.com/HTML/I_ASTROP/I14/I14.HTM

Yup, rods and cones...rods and cones...sometimes it feels like the camera can see better than me...funny how biology is just another dimension we have to face along with composition and technology just to take pics...

Mike

AfterImage

I think the false colors of the starts has to do with the sensor and the higher ISO setting used.
The increase in ISO forces the sensor into a "faking" higher sensitivity to the light. The sensor will begin to guess what colors it is seeing and will fill in the pixels on an average of what it thinks it sees.

Either that or I'm just guessing

Dramatapix®

AfterImage wrote:

I think the false colors of the starts has to do with the sensor and the higher ISO setting used.
The increase in ISO forces the sensor into a "faking" higher sensitivity to the light. The sensor will begin to guess what colors it is seeing and will fill in the pixels on an average of what it thinks it sees.

Either that or I'm just guessing

I like MMRoden's answer better.

If you can provide evidence of your theory, as he has his, I might be swayed here.

ajgauthier

ummmm...there are "colors" to stars...
hi - thought I'd pipe in here...I'll preface this by saying I'm an astronomy educator and 'celestial concierge' on the weekends for resorts.

Stars have different "colors". I put colors in quotes because color for a star means so much more than the 'visible' color 'we mere humans and visible light detectors' """see""" "Star Color" relates to temperature relates to mass relates to radius relates to where the star is in it's lifetime/evolution.

Yes, there are stars that emit more red light, blue light, yellow light. We can see those differences in telescopes, binoculars, and long exposures in cameras. Go out to a dark location some night and look around with your eyes. You may notice slight "this star over here looks more blue/white than that star over there". Take a pair of binoculars to the stars! You can definitely see color differences with binoculars. Good examples are Vega in Lyra (very blue/white bright star) as compared to Antares in Scorpius. With a small telescope (right now in fact) you can look at a "star" in the Summer Triangle in the constellation of Cygnus called Albireo. Indeed, it is actually 2 stars that look like they are a physical pair in space, seeming very close to each other. One is a brilliant blue and one is a brilliant yellow!

So - yes, you can get "star colors" in star trails and constellation photos. Even 15-20 seconds is enough to get star color differences in constellations. Take Orion - are all the "bright stars" of his shoulder/knees all the same color? (answer: nope!) Orion is a very colorful constellation!

I digress...

In the processed star trails you showed us (great job for a first try by the way! ), I think you slightly overprocessed the contrast a smidge, and that's why your colors look very exaggerated. Your background sky is awfully black...so I'm thinking you pumped up your levels or something?

Anyhoot - just wanted to clarify that stars do have different colors :

I have a question though about how you did the shot. I notice on the trails that they are not "smooth" in that I can see some 'dot/dashed' looking features in the trails...as if...you exposed for 15 seconds, then maybe covered the lense or something or closed the shutter for a few seconds, then started the trail again. I can't quite figure out why your trails aren't smooth.

what was your process for that particular photo?

Adrienne

Dramatapix®

ajgauthier wrote:

hi - thought I'd pipe in here...I'll preface this by saying I'm an astronomy educator and 'celestial concierge' on the weekends for resorts.

Stars have different "colors". I put colors in quotes because color for a star means so much more than the 'visible' color 'we mere humans and visible light detectors' """see""" "Star Color" relates to temperature relates to mass relates to radius relates to where the star is in it's lifetime/evolution.

Yes, there are stars that emit more red light, blue light, yellow light. We can see those differences in telescopes, binoculars, and long exposures in cameras. Go out to a dark location some night and look around with your eyes. You may notice slight "this star over here looks more blue/white than that star over there". Take a pair of binoculars to the stars! You can definitely see color differences with binoculars. Good examples are Vega in Lyra (very blue/white bright star) as compared to Antares in Scorpius. With a small telescope (right now in fact) you can look at a "star" in the Summer Triangle in the constellation of Cygnus called Albireo. Indeed, it is actually 2 stars that look like they are a physical pair in space, seeming very close to each other. One is a brilliant blue and one is a brilliant yellow!

So - yes, you can get "star colors" in star trails and constellation photos. Even 15-20 seconds is enough to get star color differences in constellations. Take Orion - are all the "bright stars" of his shoulder/knees all the same color? (answer: nope!) Orion is a very colorful constellation!

I digress...

In the processed star trails you showed us (great job for a first try by the way! ), I think you slightly overprocessed the contrast a smidge, and that's why your colors look very exaggerated. Your background sky is awfully black...so I'm thinking you pumped up your levels or something?

Anyhoot - just wanted to clarify that stars do have different colors :

I have a question though about how you did the shot. I notice on the trails that they are not "smooth" in that I can see some 'dot/dashed' looking features in the trails...as if...you exposed for 15 seconds, then maybe covered the lense or something or closed the shutter for a few seconds, then started the trail again. I can't quite figure out why your trails aren't smooth.

what was your process for that particular photo?

Adrienne

Adrienne~

I was on a dock on a lake with other people, and manually held the shutter open in bulb mode. I'm guessing it is due to movement, shaking of hands, and dock movement.

As far as the black sky, I did adjust the levels in PS Elements because quite frankly the original had many, many more stars in the picture. I'll upload the original tonight when I get home from work so you can see the difference.

Thanks for the information on the colors though, very insightful.

Brett

ajgauthier

ah yes, the dock and your hand!

Dramatapix® wrote:

Adrienne~

I was on a dock on a lake with other people, and manually held the shutter open in bulb mode. I'm guessing it is due to movement, shaking of hands, and dock movement.

As far as the black sky, I did adjust the levels in PS Elements because quite frankly the original had many, many more stars in the picture. I'll upload the original tonight when I get home from work so you can see the difference.

Thanks for the information on the colors though, very insightful.

Brett

ah yes...holding the 'button' for the exposure with your hand on the camera would cause the shake...as well as some slight dock movement.

If you are still interested in doing more astrophotography, you can get a shutter release cable, they run about $20 or so now I think. That makes it easy to not rattle the camera and you don't have to stand there holding it with your hand...lock it and walk away!

I'll look forward to seeing the unprocessed pic.

Adrienne

vermenton

ajgauthier wrote:

ah yes...holding the 'button' for the exposure with your hand on the camera would cause the shake...as well as some slight dock movement.

If you are still interested in doing more astrophotography, you can get a shutter release cable, they run about $20 or so now I think. That makes it easy to not rattle the camera and you don't have to stand there holding it with your hand...lock it and walk away!

I'll look forward to seeing the unprocessed pic.

Adrienne

you should try to shoot the star trail with reference point like landscape or tower, it will give dimension to the picture.

Dramatapix®

vermenton wrote:

you should try to shoot the star trail with reference point like landscape or tower, it will give dimension to the picture.

Thank you for the tip.

Brett