This is the result of my first attempt photographing star trails. I thought it would be nice to do a brief write up up about how I prepared, how the shoot went, what went right, what went wrong, and what I will plan to do differently next time.
My hope is that I can get some good suggestions to put to use on my next shoot and that others who are gearing up for their fist attempt may be able to glean something from my write up (and the responses that hopefully follow).
I had been reading up on how to photograph the night sky for about a month. I picked up an ephemeris app, started monitoring the weather, learned about clear sky charts, and read all I could find on how to best capture star trails.
For the location I settled on a small ledge I knew which is about an hour from my house. I chose the location pretty much just on it being relatively far from the city and because I had been their before and knew my way around (helpful for finding your way in the dark). The plan was to get to the park, hike a couple of miles to the ledge, start shooting around 2am, and shoot into twilight (around 5:30am) to get some light on the foreground which I knew would be dark as it was just two days before the new moon.
The forecast was finally looking decent for the evening of Friday, March 9th. I felt that had learned as much as I could from the internet and I had a plan; it was time to shoot. I left my house around 11pm, got to the location at midnight, gathered my gear together and headed out to the trail head around 12:30am. Right before I got to the trail head I decided it was time to locate the north star to ponder composition on my way up to the ledge. After locating the north star I started to think that perhaps a view of the ledge from below would make a better image. I then realized that this was my first time photographing star trails and therefore I would likely make some mistakes. Suddenly, a shot from the lower (and much closer) location became much more appealing
I decided to take the lower shot and headed out to the other end of the lake which is below the ledge. I thought I could get a nice composition from there and would also be able to get some star trail reflections. After arriving at the general shoot location around 1am I began to shoot some test shots at ISO6400 and wide open in order to find a good spot to shoot from. After finding my spot and figuring out my exposure base on the appearance of the test images on the back of the camera, it was time to focus. I settled on f/4.5, and a 2 minute exposure time at ISO 400.
The aperture was set based on me reading that wider was better and that wider makes stars brighter. I didn't know if this was what I really wanted, but knew I needed to start somewhere and thought this would be my best guess. Exposure time was set based on me wanting to keep it at or below two minutes. In the past I had noticed a real increase in noise when exposures go above two minutes for other types of shots, so I thought two minutes would be a good starting point. ISO came out to be 400 which was fine. I took a dark frame at my chosen settings and at 1:45am it was finally time to shoot.
I set up my Magic Lantern bulb exposure and intervalometer and the camera started clicking away. Everything was going smoothly and the exposures looked good in the LCD. At about 3:00am I noticed that the images were coming out foggy and discovered condensation on the lens. There was a lot of condensation on the lens and I also noticed that condensation on the tripod was starting to freeze. I decided that it was time to end my session, so I took my camera off the tripod, dried and cleaned the lens, took a +2EV light exposure, took two final dark frames and headed home. I was kinda bummed, but halfway expect battle the learning curve to some extent on my first shoot.
After transferring the files to Lightroom I noticed that the images actually got foggy around 44 minutes rather than 1.25 hours when I noticed it in the viewfinder. Oh well, at least I had a few images and could work through the assembly process. As it also turns out, the the images were all underexposed by about one and a half stops. I'm attributing this to the fact that I didn't turn my viewfinder brightness down, it was too high, and that it resulted in me overestimating the exposure. It also turned out that I must have bumped the tripod and changed the focal length while cleaning my lens off tripod. I could not get the final light image I took for the foreground to align with the rest of the images.
Here is the result of my 44 minute exposure without the foreground lighter foreground frame. Lesson learned, don't rely on iphone apps to locate the north star; learn to locate it yourself. I intended the north star (and the center of the spinning) to be about 1/3 down into the frame and a little bit to the right
Startrails1 by Doidinho, on Flickr
And now for the questions.
What do you do for dew?
I searched around and it appears that a dew heater (made for a telescope) may be the ticket. I called up the closest store that stocks them (a couple hours drive by car) and they were super helpful, but didn't have any actual experience using them with camera lenses. They suggested I try a Kendrick heater with an Astrozap controller. Does this sound right? Anyone have any first hand experience using these?
What do you do if dew does form? Is there a way to successfully fight it while shooting?
How do you monitor it? I don't think I could see it without shining a light in the lens and ruining a frame.
How do you expose and compose when shooting into the night?
f/4.5, 120s, ISO 400 was at least 1.5 stops over this time, so next time should I just set it to f/4, 120s, ISO 800 and start shooting around twilight? Are there or do you have any rules of thumb for seting exposure when shooting into the night?
What if I start out too soon and end up underexposing? Do I just adjust everything manually until I zero in on the perfect settings and then take a little bit longer break, set the intervalometer and bulb timer, and then resume shooting?
How do you locate the north star prior to the star being visible in the sky?
Thats about it for me tonight. Any comments, critique, advice, or additional questions would be appreciated.