As you probably I know, I love weird lines and shapes.. so I had to shoot the Badwater salt flats, but I also wanted something a little different from the usual. I made the detour to get there on my way back home from the Eastern Sierra, and found myself a nice spot, set up, and settled in with my book for 3 hours while collecting starlight...
This is actually 2.83 hours, or 34x 5 min exposures stacked. I've found the ideal exposure (for my style) is iso 400, f/5.6, and 5 min increments. So as soon as that exposure doesn't yield any blown out skies I start collecting light. The exposures are controlled with the canon TC80N3. The wider the lens, the longer you need to shoot to get nice trails.
I used my sigma 15mm fish eye and did some distortion correction to round out the trails. That dark hill is supposed to have a little more detail in it, the psd version does. I did have to clone out some car headlights. And I'm also not sure why there are some really short trails.. I guess some weird atmospheric thing or something (it's not the first or last file, so I don't know which it is..).
excellent image, love how you worked with your comfort and merged the images. I would have spent the whole night trying to get my exposure and missed the whole thing
This is a totally delightful image. I also greatly appreciate the technical info you you provided. Would you mind also sharing how you stacked the images, and if the moon was visible (extra light)?
I love it. Very unique take on the well known spot. It looks like the Polaris has a bit of movement (or mabye it's another star very close to Polaris)... is that a tech error or something that happens naturally (I've never shot startrails for longer than 30 minutes so I'm not sure...)?
Dec 31, 2008 at 05:08 PM
Mark Metternich Offline • • • • • • Upload & Sell: On
stanj wrote:
This is a totally delightful image. I also greatly appreciate the technical info you you provided. Would you mind also sharing how you stacked the images, and if the moon was visible (extra light)?
Thanks!
I opened the images in a stack, converted the stack to a smart object, and used 'maximum' blend mode. That's the same (as far as I can tell) as using lighten blend mode on everything. Now, for the web size image that works fine.. but at 100% you can see the little breaks in the stars (from using incremental exposures), which will show up in print.
If you use 'screen' blend mode (or if using a smart object) I think it's something like sum, total, or something like that, then you don't get the little breaks. But then it's really hard to get the rest of the image to look right.. because you're adding up all the sky as well. So you have to drop the exposure in the raw files, and do them in little batches, and then put those together, etc. I'm pretty sure that by combining the two techniques it should be possible to entirely eliminate the gaps and keep the same sky/foreground, but that will take lots of time (even on all 8 cores of my mac pro and 7 gigs of ram... so before I print I'll have to spend some more time).
Another method is to duplicate the image, find the center point, rotate the stars about it a little, and paste that onto the original in lighten mode, but to get the trails to line up perfectly is pretty much impossible, especially if you have any kind of distortion.
stanj wrote:
...and if the moon was visible (extra light)?
There was actually a very small slice of moon visible, but it was so minute that I doubt it contributed much (this was from two nights ago). The trick is to start shooting before it's completely dark, then you still have some glow from the sun (somewhere between 1/2 and 1 hour after sunset). That's also how you get nice blues in the sky, and in my case a little pink in those clouds. The trouble is finding the north star when it's still bright out! Even with a compass and knowing the declination of where you are hasn't helped me nail it, so there's about 10 min where you've got to pay a lot of attention. I do my best with the compass, then shoot a 3-5 min exposure and look for the center of rotation as soon as a few stars are out, then adjust, and start the exposure.
This works best when you've got a bright foreground, like white salt flats Otherwise yes, timing it so you have a bit of moon would help, but then you get less stars.
Also of note - I used almost 3 full batteries for this. Each one lasted about an hour (fully charged and kept warm till I put it in). So you gotta be careful that as soon as it dies (ie. the shutter isn't retriggered) that you're there to stick a new one in quickly! Using a grip with an extra battery would help mitigate that, and the newer cameras are probably a little more efficient.
milanissimo wrote:
I love it. Very unique take on the well known spot. It looks like the Polaris has a bit of movement (or mabye it's another star very close to Polaris)... is that a tech error or something that happens naturally (I've never shot startrails for longer than 30 minutes so I'm not sure...)?
That is natural, I've seen it in all the star trails I've done with Polaris - it's just minimal movement, so it's the 'north' star
This is an amazing picture... The salt flats, the mountains and the stars all combine beautifully. The image is pure magic!... I'm sure it will look stunning on a wall.
cheers,
bruce
This has got to be one of the coolest Badwater shots ever! Thanks for sharing the details of your processing. I still have to test out the 5D mkII to see how well it can handle a single exposure of around 1 hour. Probably will have to stay with stacking, but eventually it would be nice if digital could handle this as well as film did.
