Star Trails

USAIR

Last month I took a little backpacking trip.
Had a great time good fun


Here's a couple I took while out the first one camping at a friend’s farm.
I like both and think it's a good start but I think the 20D is capable of better.
This is about all I could milk out of these shots...both shot in RAW.
What could I have done better?

Any tips or comments :ear

10 mins at f/4 iso 100



40 mins at f/11 iso 100



Thanks for the look
Fred

Tee Why

first one is a touch noisy but they are well composed.

USAIR

Tee Why wrote:

first one is a touch noisy but they are well composed.

Yes very noisy hoping for tips on getting rid of all that noise

Thanks for the comments
Fred

Tee Why

Some RAW programs like RawShooters have a noise reduction built in.
Noise Ninja is another program that many consider as nice and works for JPEG images.

DJ-S1

Did you use custom function 2? It's for long exposure noise control. I like the first one quite a bit, maybe b&w would disguise much of the red noise?

gluwater

DJ-S1 wrote:

Did you use custom function 2? It's for long exposure noise control. I like the first one quite a bit, maybe b&w would disguise much of the red noise?

All the long exposure noise reduction feature does is black out any dead pixels you have. The noise in this shot looks like an exposure boost during post. There is no such noise in the second shot so I think it was caused in post, did you have auto exposure on in ACR or whichever RAW processor you use? Check out this link Fred, it is a good article on long exposures.

Star Trail Photography

USAIR

DJ-S1 wrote:

Did you use custom function 2? It's for long exposure noise control. I like the first one quite a bit, maybe b&w would disguise much of the red noise?

Yes I did...I shoot all my night shots with noise function enabled.
40 min exposure means waiting 80 mins from the time you trip the shutter.

These very long exposures plus the noise funtion take very long time.
You only get a few tries a night.

Thanks for the help and the nice comments
Fred

USAIR

gluwater wrote:

All the long exposure noise reduction feature does is black out any dead pixels you have. The noise in this shot looks like an exposure boost during post. There is no such noise in the second shot so I think it was caused in post, did you have auto exposure on in ACR or whichever RAW processor you use? Check out this link Fred, it is a good article on long exposures.

Star Trail Photography

Nick I think you may be right on post creating the noise.
If I remeber the shot was way under exposed and had to crank it up.

Also thanks for the great link he has some great photos.
Wish it wasn't raining I'd go out this weekend

Thanks
Fred

controld

What is the red light source in shot #2? Camp fire embers?

- Mike

USAIR

controld wrote:

What is the red light source in shot #2? Camp fire embers?

- Mike

Yes it was a camp fire.
I will do better next time just starting on this.
You have a lot time doing nothing with these shots and it was cold that night so a hot fire and a good drink was in order.

Fred

BPCooper

I like the second one and both are good tries at star trails. Perhaps a bit noisy, but what bothers me most in the first is that I'd like to see more stars and less barn. Perhaps back up from the barn more and use an even wider lens.

Are those city lights in the second?

gus

2nd one is supurb...great shot. I love the blue in it.

USAIR

Thanks again everyone

Weather here is terrible rain rain rain hopfully back out soon :cry

Fred

kres

I LOVE the second shot.

{I've gotta give that a try! Thanks for the idea!}

erich6

I agree with the previous comments about the first one having too much noise from underexposure and post-processing compensation.

The in-camera noise reduction does more than compensate for "bad pixels", it also eliminates systematic biases in the sensor chip which become more noticeable when they are proportional to the amount of light the sensor is detecting. It also can eliminate nonuniformity from "hot spots" or stray light.

I've never done this type of shot but I've read that you can improve them if you "paint" the foreground elements with a bright source for part of the long exposure that way you don't have to stretch the image in post because it will be properly exposed. The sky will remain black and you should get nice contrast with the stars. I think this is why your second shot is better because you had the campfire provide some illumination for the trees and you didn't have to push it in post.

Erich

erich6

OK. I wanted to resurrect this thread because I went ahead and tried doing some long exposure shots with my 20D and was disappointed with the "noise reduction" performance.

I took a 1-hr exposure of the sky in very cold weather and away from light polution (I was in Death Valley). The resulting image still looked very "noisy". Upon closer inspection it was apparent that the "noise" wasn't really your typical high ISO noise you get. The noise were actually *outages*. The pixels read R:0, G:0, B:0. No data. That tells me that these pixels were all either unresponsive (not likely) or just too hot (more likely) and saturated over the long exposure. When doing the noise reduction you get the same saturated value in both the image and the dark frame and you end up with 0's for pixel values.

I'm adding a link to a thread in the Techniques forum that talks about this and recommends using "stacking" of shorter integration time frames (~30 seconds or so).

http://www.dgrin.com/showthread.php?t=19098

I'm not sure if using NR still makes sense using this technique. While NR will do OK for stray light issues or just subtle non-uniformity issues it won't do much good for hot pixels. These will likely read the same values in the image and dark frame and you'll end up with outages.

Erich

grimace

Nice work. I like the 2nd shot the best.

jbswear

As said, too much noise on the first shot. I love the red on the second, though. Star trails aren't natural, so I think the unnatural red hue from the fire adds to the effect.

Beautiful shot.

Marc Muench

USAIR wrote:

Last month I took a little backpacking trip.
Had a great time good fun


Here's a couple I took while out the first one camping at a friend’s farm.
I like both and think it's a good start but I think the 20D is capable of better.
This is about all I could milk out of these shots...both shot in RAW.
What could I have done better?

Any tips or comments

10 mins at f/4 iso 100



40 mins at f/11 iso 100



Thanks for the look
Fred

These are both fun shots!
I do one of two things when processing long exposures, darken the shadow areas so as the noisy effect becomes minimal, or make a mask in photoshop of the shadows and gaussian blur that masked area. The later is basically what noise ninja does. However, if I had the opportunity, and wanted detail in the barn I would have filled in some light with a flashlight