{"id":24762,"date":"2025-08-02T05:48:42","date_gmt":"2025-08-02T03:48:42","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=24762"},"modified":"2026-10-27T18:00:05","modified_gmt":"2026-10-27T17:00:05","slug":"omegon-moon-filter-for-telescopes-13-125","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/omegon-maanfilter-voor-telescopen-13-125\/","title":{"rendered":"Omegon Moon Filter 13%, Transmission, 1.25 inch"},"content":{"rendered":"

The Omegon Moon Filter 13% is a neutral grey filter with 1.25 inch filter thread that allows 13 percent of the light through and blocks 87 percent. It is the most heavily damped fixed version, intended for telescopes with an aperture of about 200 mm; for smaller telescopes there is the 25%th version<\/a>.<\/p>\n\n\n

Does this fit on your telescope?<\/h2>\n\n\n
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\"Omegon<\/figure>\n\n<\/div>\n\n\n
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Yes, if the eyepieces are 1.25 inches: the tube that slides into the telescope is 31.7 mm thick. The filter screws into the filter thread at the bottom of the eyepiece; almost every 1.25-inch eyepiece has that thread, even the eyepieces that come standard with a telescope. A 200 or 250 mm Dobson telescope usually has a 2-inch focus adjustment with a 1.25-inch adapter; the filter then just goes into your 1.25-inch eyepieces. If you use a 2-inch eyepiece, then choose the Omegon Premium Moon Filter 13% 2 inch<\/a>. A 1.25 inch Barlow lens with filter thread at the bottom also takes the filter.<\/p>\n\n\n

Opening of your telescope<\/th>Which transmission<\/th><\/tr><\/thead>
from 200 mm<\/td>13%, this filter<\/td><\/tr>
150 to 200 mm<\/td>13% on a full moon, 25% on a half moon; in doubt, 25%<\/td><\/tr>
up to 150 mm<\/td>25%<\/td><\/tr><\/tbody><\/table><\/figure>\n\n<\/div>\n\n<\/div>\n\n\n

What does it do?<\/h2>\n\n\n
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A 200 mm mirror captures more than twice as much light as a 130 mm one, and a 250 mm one almost four times as much. At full moon, the image is therefore so bright that after looking at it you have a second image and can no longer see any detail in the bright parts. With 13% transmission, the image is almost eight times darker: crater rims, the rays around the crater Tycho, and the gray differences between the dark plains remain visible. At half moon through a 200 mm lens, 13% is still usable; at a narrow aperture you look without a filter. Venus and Jupiter are bright enough for this filter; Saturn and Mars become too dark with it. The sharpness does not change: the filter does not magnify or add any detail; it only removes light. What you can see on the moon is shown in The Moon through a telescope<\/a>; Which transmission goes with which opening in the Moon filter guide<\/a>.<\/p>\n\n<\/div>\n\n\n

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\"Omegon<\/figure>\n\n<\/div>\n\n<\/div>\n\n\n

Key data<\/h2>\n\n\n
Specification<\/th>Value<\/th><\/tr><\/thead>
Transmission<\/td>13%<\/td><\/tr>
Mount<\/td>1.25-inch filter thread<\/td><\/tr>
Color<\/td>Neutral<\/td><\/tr>
Material mount<\/td>Aluminum<\/td><\/tr>
Series<\/td>Basic<\/td><\/tr>
Recommended opening<\/td>From about 200 mm<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n

Which variant suits you?<\/h2>\n\n\n

Omegon has the moon filter in 13% and 25% transmission, each in 1.25 inch and 2 inch, plus the Premium with about 30% and a variable polarizing filter.<\/p>\n\n\n