M58 Camera Lens Adapter for 1.25" Star Analyser
M58 Camera Lens Adapter for 1.25" Star Analyser for "OBJECTIVE GRATING" Configuration
You can now use a dSLR to take the spectrum of a star and other celestial objects by using this adapter in combination with the Star Analyser 100 that is available separately.
With the Star Analyser 100.... ...turn this... ...into this!
Below is a spectrum taken with just a DSLR showing a Wolf-Rayet star. See the Carbon emission lines? That’s the photosphere fluorescing from UV light! The photosphere on a Wolf-Rayet star is dense, high-velocity wind region surrounding the star. Even with simple equipment, you can easily spot the Carbon peaks because Doppler shift from the winds has widened them. (Wikipedia link)
(Image courtesy of Janet Simpson: Canon 350D, EF 85mm, Star Analyser 100, and an AstroTrac mount. 30 second exposure, F1.8, x 6 stacked, ISO 400)
You can capture images like this with your DSLR. The M28-M58 adapter attaches a Star Analyser or Rainbow Optics grating to your DSLR lens. (See photo below.) This is called an “objective grating” configuration. It produces spectra that are two or three times better in resolution when compared to mounting your grating between a telescope and camera.
This is an excellent way to get started if you don’t have a telescope. Great for use in educational settings.
Above: Our adapter is made of black-anodized, light-weight aluminum. It screws into your DSLR lens cap/filter threads. Your grating then screws into the adapter. Use it with a Star Analyser, a Rainbow Optics Star Spectroscope, or any filter grating (including nebula filters, etc.)
Your Star Analyser or Rainbow Optics StarSpectroscope grating (or any 1.25″ filter) screws directly into the 1.25″ inner threads of our AD-58 as shown above.
For the best spectra, use with an 85 to 150 mm lens. You don’t even need a driven mount! For brighter objects, simply orient your grating so that the star-drift is perpendicular to the dispersion direction. For additional information on capturing spectra with a DSLR and tripod, see our pdf on drift spectra:
Technical details: Our adapter’s male threads are 58 mm and screw into the female filter (lens cap) threads on the front of your DSLR lens.
If the filter threads on your camera lens are not 58 mm, you’ll need a step-down or step-up ring.
If you order an adapter ring, “From”-end of the ring should have male threads that match your lens’ filter threads. This is generally referred to as the “first dimension.”
The “To”-end of the ring should be 58 mm female into which our M28-M58 screws. And this, not surprisingly, is considered the “second dimension.”
Q. “How can I determine the diameter of my camera’s lens’ filter threads?”
A. Some lens contain an imprint that shows their diameter. For example, the image below indicates 58 mm diameter lens threads:
If your camera does not have a call-out like the one above, you will need to do some research on your specific lens. Often, vendors’ spec sheets will indicate the lens cap/filter thread size. If your camera’s filter threads are less than 58mm, you need a step up ring: link. If your camera’s filter threads are more than 58mm, you need a step down ring: link. Also see their sets: link. Pay particular attention to their delivery times, which vary from size to size. Also (although a bit more expensive) see Adorama (link) and B&H (link).
Contact us with questions (link) or visit your local camera shop and tell them you have a 58mm filter you want to mount on your camera lens.
WATCH ON YOUTUBE: How to capture star spectra in your backyard
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