Telescopes & Astronomy

Bring out the best in your nebulae astroimages with the H-alpha H-beta OIII (Hα-Hβ-OIII) Imaging Filter for the 8” RASA. This specialized filter allows high transmission of light from emission nebulae while blocking light pollution, helping to make your images pop with detail off the black sky background with superior contrast.

Fortunately, many sources of light pollution have relatively discreet emission spectra; they emit primarily at specific wavelengths of light. By strategically blocking these “bad” wavelengths, the filter essentially eliminates the effect of light pollution while letting the “good” wavelengths of light associated with the emission nebula pass through to the camera. You’ll notice much higher contrast in your images immediately, even if imaging from your light polluted backyard! And since the transmission at the key wavelengths is so high, the nebula will not be dimmed—only the background will be blacker.

The ZWO 7nm OIII filter is centered around the Oxygen III band of 501nm. Oxygen III or double ionised oxygen occurs at  primarily at 500.7nm and secondarily 495.9nm.  The highest levels of OIII are usually found in diffuse and planetary nebulae. The OIII emission lines were first discovered in the 1860s in spectra of planetary nebulae.  OIII wavelengths relate to the green-turquoise-cyan in colour on the spectrum whilst the narrowband width makes the background space very black.

If you need to keep your imaging accessory weight down, this guidescope is just the thing.

NOTE: Weight of the guidescope is 300 grams. 

• Custom made for CGX and CGX-L Mounts
• Adjustable bracket angle for best accessibility
• 6x magnification
• Simple reticle map easily locates the celestial pole without the need to reference an app or location & time
• Scope tilt is adjustable to allow for accurate polar alignment

Getting your back-focus distance right is essential for sharp, well-corrected astrophotography and sometimes you need more than thin shims to bridge the gap. This M48 x 0.75mm aluminium alloy spacer ring provides 5mm of solid, threaded spacing to help you build out your imaging train with precision. Also available in various sizes to suit your specific setup requirements.

• Equatorial wedge for Celestron NexStar 6/8SE and Evolution Alt-Az mounted computerized telescopes
• Enables long exposure astrophotography and autoguiding by tilting the telescope’s azimuth into an equatorial platform allowing it to track an arc around the polar axis.
• For beginner to intermediate planetary and deep space imagers
• Captive hardware, tool-less operation, easily adjusts under load
• All new hefty yet portable design
• Sturdy latitude adjustment screw with easy to read scale and integrated Bubble level