Long Exposure Star Trails Photography

February 24, 2012  •  Leave a Comment

Pinwheel effect around Polaris

Pin Point Star Trail

Pin Point stars

So it was cold last night. Really cold. The kind of cold that paralyzes many people and things in Florida. It was down in the low 20′s eventually. While I am not a fan of the cold, it does in fact leave us with one benefit. It’s these really chilly nights that leave the sky FILLED with stars. More stars then I would typically see in any other given night. I live where many people would consider country. However, there is Gainesville to the north about 25 minutes and Ocala to the south about 25 minutes. Being between these two towns I  lose a lot of sky at night due to light pollution.

It was during one of these “cold snaps” last winter that I decided to try my hand at a star trail photograph. I’d been wanting to try this for the longest time and was really inspired by a guy out of Portland, Oregon named Ben Canales. If you want inspiration check him out!  In all honesty, they are REALLY easy to do and impress people instantly but take lots of experimentation. All that you will need to do them are a few basic items.

First, you MUST have a DSLR camera. You know, “the nice camera”.  I will tell you why in a moment. Second, you will need something to stabilize your camera on like a sturdy tripod and finally you will need a remote shutter release. I have both a remote controlled one and a wired plug in one. Either one will work and they are SUPER cheap to buy through vendors such as BH Photo and ebay costing about $10.

The reason you will need a DSLR is twofold. First, a DSLR has the ability to shoot in full manual mode. An extension of manual mode is “Bulb Mode” typically found within the “manual setting” itself. “Bulb Mode” is what you will use for extended timed shutter release photos. “Bulb Mode” allows the user to tell the camera how long to stay open for. In other words, YOU are the boss of the camera and this is important when dealing with long exposure photography.

I have found that much of it is experimentation and trial and error. You typically want to go out on a dark and clear night with no clouds or even passing clouds as they will inevitably find their way into the photo. Also, I have found that typically midweek ( tues-thursday) after about 11pm provides the best times to shoot up at the sky if you are near light pollution as the sky will be darkest then with minimal light pollution.

So the first step is to get the camera into “Bulb mode” and plug in your remote shutter release if you have one, otherwise make sure there are batteries in your remote controlled release. Basically, you push the button down and lock it into an “on” position  until you decide to release it and close the shutter. Star trail photos can range anywhere from 30 seconds up to hours in duration. The length of the shutter being open is what really determines  the outcome. 30 second exposures will give you more of a pin point star effect and many minutes in length with give you the artistic star trails that many people enjoy.  The real reason you need a DSLR and not a point and shoot for this type of photography is that DSLR’s have a larger sr then a point and shoot. This is the part of the camera that collects the light and turns it into an image. The larger the sensor, the more light gathering ability it has and therefore the more sensitive it is to light as well as a decrease in noise. Noise is a by-product of shooting in dark environments like a dark room or at night. The image looks grainy and unappealing. However, don’t fret. Noise WILL happen and there is nothing you can do to stop it completely. However,  thanks to post processing software like Adobe Lightroom and Canon Digital Photo Professional (DPP) you can help minimize it’s appearance after importing to your computer. If you REALLY want to get into night photography I suggest you save up for a full frame DSLR such as the  Canon Mark 5D or  Canon 7D. I shoot with Canon and am most familiar with it’s gear. A full frame camera has a sensor that is near identical to a 35mm film camera.  The sensors are bigger and as I said, can gather more light easily with less noise artefact. They are not cheap though and NOT necessary but if you want to get serious about shooting star trails it is a must. I actually shoot with my trusty Canon T1i Rebel which is about 3 years old and is what is known as a “crop body” camera. It is not a full frame sensor but instead smaller.  I’ve been more then impressed with it and it’s capabilities though. While I feel like I am due to graduate to the next price range, I cannot say enough great things about  this little camera! Most of my photos on my website were taken with either a little Canon Powershot SD600 point and shoot or my T1i. Nothing more.

So, your camera is securely mounted to a tripod because you DO NOT want any motion at all to ruin your time and effort which is also why you are using a remote trigger so you do not have to physically touch your camera. You will point your camera up at the sky and will have to use MANUAL FOCUS! Your camera will not work on autofocus as there is not enough light to find contrast to focus. Switch the lens to Manual mode and turn OFF any Image Stabilization if it is on your camera. You won’t be needing it as you are using a tripod, right? It is difficult and will take a lot of trial and error but you use the ring focus and focus on a distant object like a tree in the distance or the moon if it is present. If you shoot with a full moon you will be disappointed with the outcome though because it will give too much light. Crescent moons are the best.

Next, compose something interesting in the foreground like a treeline or mountain to give your photo a subject. Living in Florida it is tough to find mountains so I try to use trees to be in my images. Once you think you have your focus where it needs to be and image composed, turn the ISO up as high as possible and take a test shot for about 15-30 seconds. Don’t worry because it will look crappy when done. This will only tell you if you are in focus and what is going to be in your image. It is not a keeper so don’t worry. Keep trying different length exposures to get a feel for what you will see then when you are ready for the shoot turn your ISO down to 100-200 and set your aperture to about 5.6 if you want a longer star trail and go lower as far as you can to get a shorter timed picture. I have found that anything beyond 45 minutes will give me nice star trails at an f-stop of 5.6 and ISO 200.

Now, once you think you have everything in place and are ready for the “real deal”, trigger the shutter and carefully place it where it will not be moved by either wind or object  and step back. Come back in 45 minutes and again carefully release the trigger to close it. The camera may take a few moments to process the image. What you should have if you were lucky enough to get your focus right, is a clear picture with some pretty cool star trails.Don’t be fooled by what you see on the camera screen afterwards. You won’t really know how good it is until you import it into the computer and begin working on things like black and white set points and white balance. Also, shoot in RAW! DO NOT shoot in Jpeg because you will have a VERY limited amount of tweaking range available once imported into your computer. RAW is very forgiving in exposure latitude and you’ll be very glad you did use it!

Finally, I have some quick points as I end here to keep in mind

1. Turn off your camera’s “long exposure noise compensation” typically found within the menu. It will make your pictures look crummy. You will remove noise in post production.

2. Remember to use the lowest ISO available if you want star trails. If you want pin point stars then you will want to experiment with a higher ISO like 400 or maybe even 800 if you plan on 30 second exposures or under.

3. There is a rule of thumb to keep in mind. When shooting stars, the more “zoomed in you are” the more the stars will move on you. If you are going for pin point stars that is NOT a good thing. So, take 600/focal length and that is the amount of time you will have before stars will begin to move. If you are shooting at 50 mm (600/50) you will have 12 seconds approximately before stars begin to move. If you use a wide angle lens then you have more time before stars begin to move.

4. Crop sensor cameras need to multiply all focal lengths by 1.5 or 1.6 ,depending on manufacturer. So, say you are using an 18-55 mm kit lens on your Canon T1i at 18mm, multiply 18 mm x 1.5 and you end up with 27 mm in actuality. Then, using the rule above 600/27=22 seconds for star movement.

5. To make an interesting “pinwheel” effect, get the North Star in your shot and watch as the stars loop around while Polaris remains stationary.

How to find Polaris using The Big Dipper

Filed under: How to's Tagged: Florida, how to, landscape photography, long exposure photography, night photography, Ocala, pin point stars, star trails


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