Telescopes & Astronomy

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

NOTE: Weight of the guidescope is 300 grams. 

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.

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.

Fine-tune your imaging train's back-focus distance with this 11-piece M42 stainless steel spacer ring set, featuring thicknesses from 0.02 mm to 1.0 mm. Combine multiple shims to achieve precise spacing adjustments down to hundredths of a millimetre—essential for eliminating star elongation and field curvature when using field flatteners, coma correctors, and reducers. Durable 304 stainless steel construction ensures each ring stays flat and rigid for years of reliable use.

M48 11-Piece Stainless Steel Spacing Shim Set for precision back-focus adjustment in astrophotography. Includes shims ranging from 0.02mm to 1.0mm thickness, allowing fine-tuned spacing between your telescope and camera for optimal image quality.