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Home Astro-Imaging Bahtinov Focusing Masks Altair Starwave Bahtinov Focusing Masks
Whether youre doing planetary visual observing, planetary imaging, or deep sky imaging, the Bahtinov Mask is a great accessory to get the best focus for your telescope quickly and easily. Credit goes to Russian amateur astronomer Pavel Bahtinov for making his idea available to the astronomy community.Starwave TM Bahtinov masks are adjustable to fit a wide range of optical tubes, unlike masks which are only able to fit one telescope. They have an adjustment lattitude of about 50mm in aperture making them very versatile. Remember to measure your tube or dewshield diameter not the optics size! Please choose a size that sits as close to the centre of the span as possible for best results, for example if your tube diameter is 150mm do not choose the 105-150mm, the better choice would be the 125-160mm.
Starwave TM bahtinov masks grip the telescope tube gently but firmly with three metal posts covered in non-scratching silicon sleeves. This prevents slippage, whilst allowing the mask to remain perfectly central. This is unlike other masks with two posts, which rely solely on gravity to hold them in position. Because of this 3-post mounting, the Starwave Bahtinov mask remains centred, whilst fitting a wider range of telescopes, saving you money if you decide to change optical tubes. So, all you need to do is measure the outer diameter of your telescope tube or dewshield, and choose a model corresponding to that OD dimension.Starwave TM Bahtinov masks are made from precision laser cut ABS plastic, which is stiff enough to remain in position, yet has enough give to make them tough without being brittle in the cold, unlike acrylic masks which are made from thick, heavy, brittle and hard acrylic plastics.How does a Bahtinov focusing mask actually work? When in place, the Starwave Bahtinov mask works by forming a diffraction pattern of spikes of light around a star or point light source, which is easily visible in your eyepiece or DSLR/CCD camera in live view mode. When the pattern becomes perfectly symmetrical, the telescope is perfectly in focus. Focusing is quick, easy and it saves you time hunting back and forth to find the optimum focus, whilst trying to judge the size of a tiny point source of light. A Bahtinov mask useful for a quick focusing re-check if the temperature changes during your imaging sessionDo Starwave Bahtinov Masks work with both reflectors and refractors? Yes they do. Even though reflectors have a central obstruction caused by a primary mirror, there is no difference whatsoever in the performance or these masks on a reflector or a refractor. Basically, the reflector secondary mirror just covers the central portion of the mask but the outer clear aperture still carries the pattern.The following range of sizes are available to fit just about any amateur telescope on the market, as well as DSLR camera lenses:Starwave TM Bahtinov Mask Size Chart:80-110mm Starwave Bahtinov Mask to fit 80-110mm OD tubes85-120mm Starwave Bahtinov Mask to fit 85-120mm OD tubes100-140mm Starwave Bahtinov Mask to fit 100-140mm OD tubes125-160mm Starwave Bahtinov Mask to fit 125-160mm OD tubes150-190mm Starwave Bahtinov Mask to fit 150-190mm OD tubes175-220mm Starwave Bahtinov Mask to fit 175-220mm OD tubes195-240mm Starwave Bahtinov Mask to fit 195-240mm OD tubes215-260mm Starwave Bahtinov Mask to fit 215-260mm OD tubes250-290mm Starwave Bahtinov Mask to fit 250-290mm OD tubes290-340mm Starwave Bahtinov Mask to fit 290-340mm OD tubesRemember to measure your tube or dewshield diameter not the optics size! Please choose a size that sits as close to the centre of the span as possible for best results, for example if your tube diameter is 150mm do not choose the 105-150mm, the better choice would be the 125-160mm.