Second attempt - Red Rock at night

So here's my second attempt in Red Rock:

Camera: 5D2
Lens: 24-70L
ISO: 800
20 second exposure at 2.8.
Mild PP to adjust sky color & one sharpening pass.

Lessons learned:

1. It gets cold out there at 2am...bring warmer clothes
2. Way too much light pollution to get a crisp, solid image out here. Time to find a new spot away from Vegas (Valley of Fire here I come!)
3. More practice needed
4. Read more about PP techniques in Photoshop

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My first star trails attempt:

Same info as above but this was a 22 minute exposure. I had StarSky on my droid and guess where the celestial north spot would be. I almost got lucky. LOL

There's so much noise in this picture but I'm not sure if it's because of the amount of light pollution out there? I shot in RAW mode and turned off all noise reduction in the camera. When I used photoshop to try and remove it....no luck.

Any suggestions?

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A little creative license with the two shots...

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VegasBoz wrote in post #10189942
My first star trails attempt:

Same info as above but this was a 22 minute exposure. I had StarSky on my droid and guess where the celestial north spot would be. I almost got lucky. LOL

There's so much noise in this picture but I'm not sure if it's because of the amount of light pollution out there? I shot in RAW mode and turned off all noise reduction in the camera. When I used photoshop to try and remove it....no luck.

Any suggestions?

The noise is due to such a long exposure at a high ISO, possibly in addition to any light pollution sky glow.

Instead of shooting one long exposure for your star trail, shoot a series of 30 to 40 second exposures then stack them together.
You can use Photoshop to do that which can be time consuming, or you can expedite matters by using Startrails and make it a little easier.

http://cs.astronomy.co​m/asycs/forums/t/37823​.aspx
http://cs.astronomy.co​m/asycs/forums/t/45250​.aspx

You can still make a dark frame after the fact. For 22 minutes you'd want to be sure that there's no chance of light getting in so I'd put the lens cap on and put it in a drawer in a dark room or similar.
Ideally you want the conditions to be the same as when you took the exposure but the difference is small compared to the difference between any dark frame and no dark frame.
Try and use an astronomical program (eg. DSS) to do the dark frame subtraction so that it's done with linear data.

Steve.

SteveInNZ wrote in post #10191161
You can still make a dark frame after the fact. For 22 minutes you'd want to be sure that there's no chance of light getting in so I'd put the lens cap on and put it in a drawer in a dark room or similar.
Ideally you want the conditions to be the same as when you took the exposure but the difference is small compared to the difference between any dark frame and no dark frame.
Try and use an astronomical program (eg. DSS) to do the dark frame subtraction so that it's done with linear data.

Steve.

Ideally you want the operating temperature to be the same also. Placing it in a drawer will most likely increase the temperature of the camera. Especially for a 22 minute exposure.
As long as you're still outside under the dark skies, just placing the lens cap on should be enough.
If the lens mount is leaking light then it's also doing it while you're shooting your light frames.
As long as the lens mount and lens cap fit properly you shouldn't have to worry about leaking light.

You can subtract darks using Photoshop as well.

Open both the light frame and dark frame in Photoshop.
Copy the dark frame into another layer onto the light frame.
Set the Blending from Normal to Difference.
You might want to adjust the oppacity, but not always necessary.
Merge layers down, and that's it.

Thanks for the additional info. I can see I have more reading to do. LOL

I tried the StarTrails software and it works great...but my stacked photo's reveal some of the problems I had with getting the time sequence uninterrupted:

1. I linked my 5D2 into my laptop and was using the touchpad to activate mirror lockup then take the timed exposure. Sometimes it would double click when I started the exposure so it was a black picture. I'd wait 8 seconds after locking the mirror up (to avoid vibration) and by then the stars had moved enough to create the black staggered spaces.

Solution: I have a TC-80N3 on the way which should alleviate those problems of bad frames due to cold fingers/shivering.

2. Light pollution problem - there's no way around this for now. It takes me 20 minutes to get to Red Rock Canyon vs 60 minutes to get to Valley of Fire. I've looked at the light pollution map on Google Earth and have picked a spot in Valley of Fire that I'll try, but until I can take a decent picture as I learn I don't want to waste my time driving out there to take crappy pictures at night.

3. Light/Dark frames - I hadn't read about this until today... so more reading to follow.

Thanks again everyone. I'm looking forward to finally getting a picture to print out and frame for myself.

Boz

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Definitely a improvement over the 1st shot, nice progress so far. Looks like you might have caught an iridium flare or a bright meteor in the 1st shot. The illumination is a little uneven, which is hard to do with landscape at night, but something to keep an eye on. You've also got a little vignetting in the corners in the sky, otherwise it's pretty good.

The star trail is noisy because it's 22 minutes and because of the light pollution. A darker sky from a really dark site would be a lot less noisy because the noise would be on a darker background.

The combine effort looks nice...what ISO was your 22 minute exposure? You HAVE to shoot at ISO 200 when you do this stuff. Don't use ISO 100 as it's not really a "real" ISO and the signal/noise ratio is better at ISO 200.

Typically when I set up to shoot a sequence of images to make a time lapse animation, or a sequence of images to be used for star trails, I use my shortest focal length lens, set at it's largest aperture(f/stop), ISO 800, 25 to 30 second exposures with only 5 seconds between each. Only 5 seconds between each will make the transition much smoother. ISO 800 seems to be the optimal gain for both my EOS DSLR cameras allowing me to get plenty of stars in each exposure without too much noise.
If I only plan on doing star trails and not a time lapse animation, I'll shot longer exposures of about 40 to 50 seconds which will allow the stars to trail a bit on their own, still with only 5 seconds between each shot.

Additionally, you probably already have heard this, Don't use Long Exposure Noise Reduction. That will use up just as much time as your exposure for each shot, and, will leave too much spacing between the stars in each frame.
You can use High ISO Noise Reduction instead and set it to Strong.
If you have hot or cold pixels in your frames, you can shoot a couple darks and subtract them from your star trail image using photoshop.

That's one thing I made sure to do this time; noise reduction in camera is off.

I've been practicing with settings on the camera and finally figured out how to automate the frame captures using the EOS utilty. But it doesn't allow for mirror lockup delays. Question is:

Will i need to worry about mirror lockup since I'll be doing 30 second exposures?

The 22min exposure was done at F8 @ ISO 800. I'll do it a different way next time obviously, probably the stack option. Although I'm going to try the ISO 200 option too...this is too much fun learning.

VegasBoz wrote in post #10197243
Will i need to worry about mirror lockup since I'll be doing 30 second exposures?

No, not when shooting the dark night sky. It takes less than a second for any vibration from the mirror flip to dampen out. Your night sky exposures are more than long enough, and the sky dark enough, to negate any of that vibration.

Shooting pictures of the moon would however be another story. Since the moon is so bright, and, the exposure relatively short, you would pick up the vibration of the mirror. Believe it or not, that's often the cause for a less than sharp focused image on many Moon shots.