I’ve been taking photos since I was about 5 and until fairly recently just with 35mm. In May 2008 I bought my first DSLR, a Nikon D80 with 18-135mm lens followed shortly after with a Tokina 12-24mm and a Tamron 28-300mm.
About the same time I started taking photos I became interested in astronomy and it was natural that I combined the two eventually. In my late teens I bought a telescope and had some success taking photos of the moon’s craters. One day I aim to purchase a better telescope to allow me to photograph many other celestial objects such as nebulae, start clusters and galaxies.
I am also interested in landscape photography and like to combine this with astronomy to shoot star trails, planets, moon etc as a backdrop to earth based landscapes. With my new venture into digital I want to work on this type of photography a lot more.
I also like animal, bird, macro (nature) and sports photography.
Long Exposures (startrails)
I replied to a forum question in the Time Lapse/Long Exposure group in relation to exposures for startrails with DSLRs that I thought might be useful to others:
It’s a bit more of a complicated process but taking multiple short exposures and combining them afterwards is the best way.
Firstly if you are getting pixelation then a lower ISO, wider aperture can reduce it substantially, but if you want to pick up more stars, nebula etc then the ISO can be increased to 800 to 3200. It’s trial and error until you get used to it. Photoshop has great sharpen and despeckle etc tools too.
If you are getting purplish patches near the edge of images, then that can’t be solved with a single exposure. I’m pretty sure that this effect occurs with most DSLRs, and certainly with my Nikon, that the digital sensors build up heat with long exposures causing a partial ‘extra’ heat exposure on the sensor resulting in purplish patches appearing on the image, especially near the edges.
The software program called Startrails is excellent for combining mutiple shots and it’s free (Google it). You can also produce a movie of the stars, moon etc moving across the sky, which looks awesome.
Another advantage of this technique is that you can use slightly higher ISO settings to bring out the fainter stars and make the bright ones brighter and more colourful, and pick up some of the nebula and more of the Milky Way.
Of course having a dark sky helps alot too! You’ll always get noise from city lights even if you take multiple short exposures unless you’re in a dark sky.
If you are using a wide angle of about 12mm or so you can take an image of stars with an exposure time of about 1 minute if you are pointing mainly towards the south celestial pole (near the Southern Cross), without the stars moving to much to keep points of light on your image (longer and you would see a short line on your image instead of points for stars). If you are pointing away from South, the stars move faster across the sky and therefore you would need slightly shorter exposures, say 30sec – 45 sec before you notice movement on your image. Of course this will depend on what focal length lens you use too, so for longer focal length, you need shorter exposures to maintain points of light. If you’re not concerned by this then do exposures of a few minutes each then overlay them.
The last thing to mention is to make sure you take them in succession so that you don’t get gaps in the trails (unless you want that!). A good timer cable remote is best for this. I bought a $40 Aputure remote on ebay and its fantastic! Better than any Nikon ones – has far more features and you can set it to take say 100 shots of 30 sec each with 1 sec in between each one. It’s great! You just walk away and leave it going. Just got to watch the camera battery though.. it never ends does it!
Well hope that helps. I don’t have many startrail images up on here but I have taken many over the years, especially on film, so let me know if you have any questions.