About this product
Part Number: 20200
This variable polarising filter made from anodised aluminium and optical glass allows you to progressively reduce the amount of light entering your eyepiece.
Reduces glare whilst increasing contrast so perfect for observing bright objects such as the Moon or certain planets.
Light transmission can be varied from 40% down to as little as 1%.
Will not change the colour of the object being viewed.
Prevents eye fatigue and loss of night vision.
Each filter set consists of two polarising filters, one which can be rotated in its cell to adjust the brightness.
The filters, used as single elements, can also be used for daytime terrestrial use for reducing sunlight glare from lakes oceans or window glass.
Available in two sizes, threaded to fit either standard 1.25” or 2” astronomical eyepieces.
Supplied with storage case.
|Average Rating (2 Reviews): |Reliable filter for use with large apertures
Thursday, 3 May 2018 | Victor
The moon with my 10 inch dob can be very bright, and this filter is very good at dimming the moon. Because you can adjust how much of the light you want to let in, you can adjust the brightness so you won't loose detail while the image not being too bright. I give it 5 out of 5 stars because of the price and functionality, but in the beginning it can be a little annoying to remove the eyepiece each time you want to either dim or brighten the image.
Overall I would recommend it because of its price and flexibility.
A must for Lunar Observing
Monday, 7 October 2013 | Andrew
I have used several ND filters with small telescopes for looking at the moon and they do a decent job. On my 12" Newtonian the Moon is painfully blinding with most ND filters I have tried. This is only filter that works, the double polariser allows you adjust the amount of light transmitted to the eye with no noticeable colour cast or reflections. To make Lunar viewing a pleasant experience again, at it's lower settings it also takes the edge of the glare from Jupiter making it easier to pick out details.
I using a single eyepiece you need to guess a little with setting but you can separate the filter allowing you to put one half in a Barlow or comma corrector (if you have one that accepts a filter) and the other on an eyepiece, this gives finger tip control of the filter as you move from fully illuminated parts of the moon to the terminator.
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