Star trails
doctorsoup
Registered Users Posts: 49 Big grins
Hi all,
I've been playing with star trails recently. Here is one that I also posted at flickr that got some attention. I have uploaded a folder here on smugmug with a few shots, and would love some feedback.
I've been playing with star trails recently. Here is one that I also posted at flickr that got some attention. I have uploaded a folder here on smugmug with a few shots, and would love some feedback.
0
Comments
please visit: www.babyelephants.net
Was there a moon out? Looks like quite a bit of ambient light there.
Cheers,
-joel
Link to my Smugmug site
This link:
http://www.liquidinplastic.com/2008/06/startrails/
by Dan Newton is a great starting point for the "how-to" on shooting star trails.
This image started out as 37 separate 30 second exposures. I stacked them together using the PS action mentioned in the article. There was about a 1/4 moon, coming from camera right, providing some illumination to the old farmhouse. I did some exposure masking to bring up the exposure on the house and the field. Then I converted the final image to sepia toning.
I have some more star trail shots in my smugmug account, conveniently located in a separate folder called "Star Trails."
http://pmcphotos.smugmug.com/Photography/Star-Trails/13896419_GG9er#1019597947_Abaei
www.doctorsoup.smugmug.com
Washington, D.C., based landscape and fine art photographer
http://navinsarmaphotography.com/
Very nice work. One nit-pick though. I don't think the gaps that Dan Newton mentions are really due to a time lapse between shots as he says. I found those gaps in my startrail photos, and I was shooting consecutively, and there was no way the stars were moving that far between shots, especially with my wide angle shots.
Its an image processing effect. Google for the screen lighten startrails method, I think there are some posts here on DG about it. I took the same stacks I had processed with lighten only and reprocessed them first stacking consecutive shots in screen mode, then stacking the whole lot in lighten mode, and the between-shot gaps disapeared. This only worked for the set I had shot in raw- for the ones I had shot in jpg, I couldn't get rid of the gaps. That tells me that the jpg compression is a contributing factor.
Your gallery doesn't have high res enough versions to see if you are plagued by the gaps- very nice shots though.
Now all I need is a programming guru to write a Gimp script to process a folder of images automatically by the screen-lighten method.
Thanks for the kind words Kolibri and steering me towards the screen-lighten method. This image has the gap problem, even though I did 30 sec exposures with only 1 sec in between each exposure, using a 20mm lens on a full frame camera. I tried this processing technique as per Floris' directions, but it did not eliminate the gaps. Now I'm perplexed, what to do next???
www.doctorsoup.smugmug.com
Hmm. Did you shoot raw or jpg? The screen then lighten workflow worked for me. I'm out of the country, and don't have my images with me, or I'd post the difference.
My set up: 28mm, full frame, 1 minute exposure, 1 second in between, shot with a timer- usually 60 to 90 shots.
Workflow:
-Shoot raw, batch convert using Bibble 1 stop under exposed. In file manager, duplicate all files except first and last- rename to add "screened" to the second file.
-Open as layers in Gimp- it opens by name in this order:
last
last-1
last-1screened
last-2
last-2screened
first
-then I combine consecutive shots with screen mode: ex
last
last-1
last-1screened
last-2
last-2screened
first
That gives me three files instead of my 4 original files, and I combine them all using the lighten only mode.
Remember (in gimp) you have to set the blending mode for each layer separately, and you can't do a combine all for the screen method for it to work, you have to do it 2 by 2. Once you've got all the pairs done, you can then set each layer mode to lighten only, make each one visible, can merge all visible layers. It does take a long time if you have to do it manually (gimp programmers, anyone want to write me a script???)
this works for me, no gaps, so now i can print out my photos HUGE.
If I try this with photos originally shot in jpg, or with a non linear stretch applied during raw conversion, it doesn't work, there must be an averaging of the final star streak pixel in each photo with the background during compression.
hope this helps- it did me.
Thanks for trying to help, kolibri! I tried this again, following your directions, but using Photoshop CS5. (I haven't used Gimp.) The original files are shot in raw. I did the raw conversion using Adobe Camera Raw to .psd files. No better results. :cry
I didn't follow this comment:
What is a "nonlinear stretch applied during raw conversion" -- ???
www.doctorsoup.smugmug.com