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Weasner's Corner Meade #905 Variable Polarizer Filter |
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For glare-reduction in observing the Moon the #905 Variable Polarizer includes two Polarizer filters mounted in a specially-machined cell. The #905 permits variable settings of the light transmission between 5% and 25%, to account for varying lunar surface brightness according to the phase of the Moon and the magnification and aperture of the telescope. Accepts 1.25" eyepieces. OPT Price: $49.95
On 14 July, 1645 PDT, I observed the 4.5 day old Moon with the ETX-125EC and a 25mm eyepiece. The Sun was still well above horizon and the Moon was nearly at the meridian. Without the polarizing filter, the Moon was washed out although some craters along the terminator were visible. With the polarizing filter, the sky was darkened (by rotating the entire filter/eyepiece unit) and thereby increased the contrast with the Moon. Adjusting the variable polarizing darkened the entire field of view with no visible improvement in the view.
On 14 July, 1930 PDT, I observed a nearly half-phase Venus with the ETX-125EC and a 25mm eyepiece. The Sun had not yet set but Venus was visible in the finderscope and eyepiece. Without the polarizing filter, the glare from Venus made observation difficult.
With the polarizing filter, Venus was a nice, just slightly more than half-phase, disk with no glare nor atmospheric distortion. This was the best view I've ever had of Venus with any telescope. Being able to adjust the amount of darkening with the polarizing filter was a tremendous asset in improving the view. (If you click on the photo of the filter you'll see a photo taken with a Nikon Coolpix 995 digital camera mounted to a Scopetronix 25mm eyepiece using the Scopetronix Digi-T System. The image is cropped from fullframe.)
On 15 July, 1930 PDT, I observed the 5.66 day old Moon with my ETX-90RA and a 26mm eyepiece. At various times I added a Meade #126 2X Barlow Lens or observed with a Scopetronix 40mm eyepiece and the Shutan Wide Field Adapter on the rear port. Even though it was still daylight, as I adjusted the setting on the filter, many details stood out, including some mountains rising above the Moon's limb.
While the Meade #905 Variable Polarizer Filter will not hamper focusing with the ETX-90 and ETX-125, and many other telescopes, it will not allow a focus to be reached when used in the ETX-70AT. But if it will focus with your telescope you may want to consider adding this accessory to your bag of tricks for enhancing your observations.
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Weasner's Corner Meade #905 Variable Polarizer Filter |
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