The Star Analyser grating screws onto your camera nose or filter wheel
The Paton Hawksley Star Analyser 100 was designed specifically for amateur astronomical spectroscopy. It can be mounted on your telescope just like any other 1.25″ filter. It’s is easy to use, and will work with most cameras. A big advantage to this 100 line/mm grating it is easier (than with a 200 line/mm grating) to image dim objects and you can display the zero-order (star) along with the spectrum. This makes it easy for you to calibrate your spectra.
Don’t think you have to have a Phd to capture and understand spectra of stars! These days, with the right hardware and software, it’s surprisingly easy.
We have customers using these gratings on webcams, DSLRs, modern video astronomy cameras, and of course classically-cooled astronomical CCDs. They’re in stock and we can ship you one today! Link.
Most amateur and professional astronomers are surprised to discover the remarkable results that a Star Analyser can produce. Using very short exposure times with a telescope (or even an unguided DSLR), this grating can produce a wide range of fascinating and scientifically accurate spectra.
Below is a spectrum of Vega made with a Star Analyser. Telescope: 8″ SCT. Camera: $50 webcam at 15 frames/second. Observing location: 4 miles from downtown Seattle. This spectrum was displayed in real-time with our RSpec software:
Vega Spectrum with Hydrogen absorption lines (8" SCT, webcam)
With a diffraction grating like the Star Analyser, you can:
Click on this link to see some wonderful spectra taken with a Star Analyser and processed with RSpec, our real-time spectroscopy software.
The Star Analyser is a high quality, 100 line/mm diffraction grating mounted in a standard 1.25″ filter cell. The grating is protected on both sides with anti-reflection coated glass. The Star Analyser also works well indoors in a lab or classroom setting.
The Star Spectroscope is an older 200 line/mm grating that many amateurs have used to get good results. Since the introduction of the 100 line/mm Star Analyser, though, most amateurs suggest that 100 line/mm is a better choice. Read more on this subject here: link.
Mount your grating just like you mount any filter cell. You can put it in your filter wheel. Or, you can screw it into your camera’s nose piece, as shown here:
The Star Analyser screws into your camera nose piece or filter wheel
You can also screw the grating into your T-Ring, using our adapter: link.
With almost all telescopes and cameras, the Star Analyser works “right out of the box” to produce great spectra in RSpec.
A good rule of thumb is that the grating should be between 30 and 80 mm from your sensor.
Spacers: In some cases, adding spacers may yield spectra with a bit more resolution.
The further away from the camera sensor that you mount the Star Analyser, the more spread out the spectrum becomes. If you mount the grating too close, you lose resolution. If you mount the grating too far away, the whole spectrum will not fit in the camera frame and dim object sensitivity is reduced as well.
In practice, the minimum recommended sensor-to-grating distance in mm is 4x your camera’s pixel size in microns. This is a rather low dispersion and there is some advantage in mounting the grating a bit further away than this minimum.
We suggest that you not be too concerned in the beginning about spacing. Purchase sufficient spacers ($10 each + S&H) to bring the sensor-to-grating distance above the minimum described above. Each spacer adds an adjustable 7-10mm. You may want to wait until you’ve seen the performance of your Star Analyser on your particular hardware before ordering any spacers. Also, rather than purchasing a spacer, you can make one by simply removing the glass from any spare 1.25″ filter cell.
If you want to fine-tune the mounting distance of your Star Analyser or Rainbow Optics diffraction grating, use our SimpleCalc worksheet: link.Also, the experts on our forum (link) are an excellent source of information. The designer of the Star Analyser, Robin Leadbeater, is a regular contributor to the RSpec forum. So is Ken Harrison, author of “Astronomical Spectroscopy for Amateurs.” (Book link) We encourage you to post your questions to our forum where Robin, Ken, and other experts can provide good answers. Also, you can read our more detailed discussion on the math of grating spacing at this link.
Use your Star Analyser or Rainbow Optics Star Spectroscope grating with your DSLR
You can get amazing results mounting your grating as an “objective grating” as shown below. Click this link for an example spectrum and additional information.
Star Analyser used as an "Objective Grating"
You can purchase a Star Analyser in our store (link). Our adapters work fine with the Star Spectroscope gratings too, however we prefer the Star Analyser grating. See this link for why.
Also, you may be interested in our grating adapter for easy mounting of the Star Analyser to your DSLR or T-Ring adapter: link.
This is a reasonable question to ask. We’re all familiar with the fact that at a certain point, adding additional magnification to a visual telescope can actually cause an image to deteriorate. Similar optical limitations occur when going from 100 to 200 line/mm gratings. A 200 line/mm grating may give a slightly higher resolution. But, a 100 l/mm grating will have significantly better faint object performance. Also, the larger deviation angle (6.4°) of a 200 line/mm grating being so far off-axis increases the chromatic aberration and eventually limits its resolution. For more information, click this link.