The Star Analyser SA-100, SA-200


The Star Analyser 100 grating screws onto your camera nose or filter wheel

The Paton Hawksley Star Analyser 100 (SA-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 works with most cameras. Capturing the spectrum of a star is easy! Use our grating, a DSLR or small telescope, and our award-winning software.

The video below shows some exciting examples of what you can do with a Star Analyser:


Also, check out this link for some great sample work done by amateur spectroscopers.

Download our one-page guide “Choosing a Star Analyser grating”

There are several ways to mount a Star Analyser grating. In addition to watching the above video, please take a look at this easy, one-page guide.



“Choosing a Star Analyser Grating”


In addition to the Star Analyser 100, we also offer a Star Analyser 200 (link). However, for most users, the SA-100 is the recommended model. We explain why below. The Star Analyser 100 is a diffraction grating with grooves that are spaced at 100 lines/mm. The grating is durably mounted in a standard 1.25″ filter cell and is protected on both sides with anti-reflection coated glass.

You don’t have to have to be a PhD to capture and understand spectra of stars! With our gratings and software, it’s amazingly easy. We have customers using these gratings on webcams, DSLRs, modern video astronomy cameras, and of course FITS images from cooled astronomical CCDs.  We have gratings in stock and we can ship you one today — see our on-line store: link.

Below is a real-time view of spectrum of Vega made with a Star Analyser, an 8″ SCT and a $50 webcam. The observing location was 4 miles from the center of a large metropolitan city. This spectrum was displayed in real-time with our RSpec software. The red line is an intensity graph of the star’s spectrum. The blue calibration lines show where we’d expect to see dips due to the star’s Hydrogen absorbing light. Notice red curve has dips exactly where the blue lines predict:



With a diffraction grating like the Star Analyser, you can:

  • detect Neptune’s methane atmosphere.
  • determine any star’s OBAFGKM star-type and temperature from its spectra curve.
  • identify the composition of a star or nebula from its emission and absorption lines
  • detect the red-shift of a distant quasar!
  • measure the blue-shift of a supernova’s expanding shell as it races towards us at millions of miles/hour.
  • watch the spectral evolution of a nova as it goes through its different phases.

Click on this link to see some wonderful spectra taken with a Star Analyser and processed with RSpec, our real-time spectroscopy software.

What’s the difference between a Star Analyser 100, Star Analyser 200, and a Star Spectroscope?



Our SA-100 grating has grooves that are spaced at 100 lines/mm. The benefit of a 100 line/mm grating compared to a 200 line/mm grating is that for a given spacing from the camera, it produces a brighter spectrum and allows shorter exposures.

In some situations, though, the SA-100 may just not physically fit. For example, when mounting the SA-100 inside a filter wheel, space may be restricted. Or, your filter wheel may position the SA100 so that it’s too close to the CCD sensor for it to create a long enough spectrum.

In the above scenarios, we offer the Star Analyser 200. Because the SA-200 is low profile, it more often fits inside the confined space of a filter wheel. And, because the SA200 spreads out the spectrum twice as much as the SA100, it can be mounted more closely to the CCD sensor.

Use our calculator page to determine whether the SA-100 or SA-200 is right for you: link.

What’s a “Star Spectroscope?” The Star Spectroscope is an older 200 line/mm grating designed primarily for visual use. Many amateurs have used the Star Spectroscope and gotten good results. However, the 100 line/mm Star Analyser 100 is easier to use and gives better results in most circumstances when used with modern digital camera technology. For specific applications where a 200 line/mm grating is necessary, we offer the Star Analyser 200. Learn more about the SA-200 here.

Use your Star Analyser or Rainbow Optics Star Spectroscope like any 1.25″ filter cell on your astronomical CCD camera

You can get amazing results mounting your grating on the nosepiece of your current CCD camera. Click this link to see some real examples of spectra amateurs have captured.



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 about 30 and 80 mm from your sensor.


In some cases, adding one or two of our 10 mm spacers ($10) may produce spectra with a bit more resolution.If you mount a grating too close to your camera, 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. Use our calculator to determine the best mounting distance of your Star Analyser grating: Questions? Contact our Help Desk for instant answers from experts: link.

Use your Star Analyser SA-100, SA-200 or Rainbow Optics Star Spectroscope grating with your DSLR

You can get amazing results mounting your grating on a DSLR as an “objective grating” as shown below.


Star Analyser used as an “objective grating”

You can purchase a Star Analyser($195) in our store: link.  For more details on the optional AD-58 thread adapter ($38) shown above, see this link.

If a 100 line/mm grating is good, is a 200 line/mm grating better?

This is a reasonable question to ask. The short answer is no. Here’s why: 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 begin to occur when going from 100 to 200 line/mm gratings.

A 200 line/mm grating, including our SA-200 grating as well as the the Star Spectroscope grating, when mounted in the same position, will spread out the spectrum twice that of a 100 line/mm grating. This may give slightly higher resolution. But, a 100 line/mm grating will have significantly better faint object performance. And often times the additional dispersion from a 200 line/mm grating doesn’t even produce better spectra. This is due to various optical limitations as described in this technical paper by Doug West: link.

Note, however, that there are some situations where a 200 line/mm grating may better serve your needs. For example, on some telescope setups, a 100 line/mm grating cannot be mounted far enough away from the camera to get good results. For example, filter wheels often have limited clearance. And when using a large aperture, long focal length telescopes and a large sensor camera, a 200 line/mm grating may give better results because of improved resolution that comes from the longer spectrum. For use in these situations, we offer the Star Analyser 200: link.