Table of Contents
COMING SOON! How to detect an exoplanet with a DSLR and the Nyx Tracker
COMING SOON! How to do Star Trail (aka "Starfield") astrophotography with the Nyx Tracker
How to Use the Nyx Tracker
Nyx Tracker Comparison
How to Assemble the Nyx Tracker DIY kit
The Nyx Tracker is designed with ease of use in mind. Below you will find the user manual that comes with the tracker. Click to enlarge. Also please reference the How to Use video above!
When taking pictures of the stars without a star tracking mount, astrophotographers use the "500 rule" to calculate exposure times before star trailing becomes apparent. For example, if using a lens with a 50mm focal length, the exposure should be less than 500 / 50 = 10 seconds, otherwise you will get star trails. Keep in mind that this is a rule of thumb, and if your target field of view is far from the poles, exposure time should be a bit shorter. Also keep in mind that if your camera uses a crop sensor, you will need to convert the lens focal length to an effective focal length by multiplying by 1.5 (or 1.6 for Canon).
The table below is the recommended starting point for exposure times when using the Nyx Tracker. It is based upon a "2500 rule." With exceptionally good alignment and stability I have been able to far exceed these exposure times (10 minutes at 12mm, effectively a 7000 rule), but I don't recommend the novice pushes it until they familiarize themselves with the entire astrophotography process and the tools used, including the Nyx Tracker.
- Your stars will appear sharper if the tracker is undisturbed by wind or footsteps while exposing. And definitely take care not to bump it!!
- It takes a few seconds for a tripod and tracker to stop wobbling after you press the shutter button - use the 10s timer feature to begin the exposure after everything is settled.
- Put your tripod on stable earth - not a car, a bench, or in a building.
- All camera lenses have aberrations - manufacturing errors that make images distorted. This is especially pronounced at low f-stops. If your lens has a variable aperture, stop down one or two stops and you'll likely see a significant reduction of aberration, especially at the edges of your images. So if you have an f/1.8 lens, stop down to f/2.0 or f/2.2 for better images.
- Full frame sensors, although more expensive, always produce better images. Not only do they have higher resolution, but each individual pixel is usually ~2x as wide. This quadruples the area and increases "full well capacity" by a similar factor. This means your signal to readout noise ratio will also be 3-4x better.
- Think about investing in a good lens. Look for something with a large aperture / low f-stop (2.0 or less) that has a focal length less than 50mm. Search the internet for "good astrophotography lenses" for recommendations.
- In order to stack and process pictures, you will need software. Here are some favorites:
- Photoshop (can both stack and process)
- DeepSkyStacker aka DSS (for stacking only, FREE)
- PixInsight (can both stack and process)
- IRIS (can both stack and process, FREE, sharp learning curve)
- I have found Dr. Roger Clark's astrophotography website to be one of the best resources for getting the most out of your data. Check out his free color stretching tool, rnc-color-stretch (this is an advanced processing tool and requires some tech savviness).
The vast majority of issues that arise with the Nyx Tracker are easy to solve. If your problem is not solved by going through this checklist, feel free to contact me!
1. My Nyx Tracker is "dead."
- Are all four AAA batteries installed in their correct orientation (springs to the minus side of the batteries)? Are the batteries fresh? Note that used batteries may fall below operating voltage in extreme cold (less than freezing).
- Does the laser respond when you press the button? If yes, turn on the motor and take it to a dark room. Do you see a red light emanating from the control board compartment? If no, contact me. If yes, see #2 below.
2. My Nyx Tracker is "jamming."
- Sometimes the threads of the drive rod get dirty and cause binding with the large gear. Take an old toothbrush and clean the threads of the drive rod.
- How old are your batteries? When the batteries get low, the current to the motor drops and thus so does the driving torque. All other operation will appear normal, but the motor gets weak. If you've run the tracker longer than ~10 hrs, chances are you simply need new batteries.
3. The Nyx Tracker is working, but I still seem to be getting star trails at the recommended exposure times. Can't I get better performance?
- Yes, you should be able to at least quadruple (4x) the 500 rule. There are two keys to good star tracking: stability and alignment. Most of the time, poor tracking is due to a mix of the two.
- Make sure the tracker is on a stable tripod (not a cheap rickety one), on firm ground, preferably concrete (not on a car, bench, or in a building).
- Use a timed shutter or remote release. Pressing the shutter button induces vibration into the tripod and tracker. This vibration can take up to 10 seconds to settle.
- Avoid walking around the tripod while it's exposing (footsteps can induce vibration).
- Hopefully there's no wind, but if there is make sure you're shielding the wind as best you can.
- Firmly tighten down all your tripod's adjustments and the tracker ball head. Sometimes friction-based joints will slowly, imperceptibly creep, especially if your camera isn't balanced on the tracker.
- If you've got a cheap tripod, try hanging a bag of rocks or weights from the center post to aid in stability.
- Good celestial pole (CP) alignment takes practice, and is one of the biggest challenges of astrophotography. Keeping this in mind, try the following:
- Make sure you've correctly identified the location of the CP. For the northern hemisphere: At lower focal lengths it should suffice to point the laser directly at Polaris. However, that's not exactly where the northern CP is! It's actually 0.75 degrees (45 arcminutes) away from Polaris, which matters if you're shooting longer focal lengths or really want to maximize your performance. Use a time and location-specific app like Stellarium to find it accurately. For the southern hemisphere: It is a bit trickier than the north because there is no bright star close to the pole! You will need some patience and references on the sky. This video tutorial should help. Use a time and location-specific app like Stellarium to find it accurately.
- Play around with where exactly you're pointing the laser. Every tracker is going to have a slight misalignment of the laser to the hinge's rotational axis (within 0.2 degree or so). You've got to find your tracker's "sweet spot." The good thing is once you find it, you can just point at that same spot forever after without worrying about it. Align it as best you know how, taking note where in relation to Polaris and the other stars you've pointed the laser, then expose for several minutes at 50mm or so. Try a different spot, and another, and another. If the trails are reducing, you're honing in on the sweet spot.
- Make sure the Northern Hemisphere / Southern Hemisphere toggle and speed settings are set properly.
Good luck in your photon capturing, I wish you the best cloud-free skies!!