Omegon Moon Filter 13%, Transmission, 1.25 inch

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.

Does this fit on your telescope?

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 1.25 inch Barlow lens with filter thread at the bottom also takes the filter.

Opening of your telescope	Which transmission
from 200 mm	13%, this filter
150 to 200 mm	13% on a full moon, 25% on a half moon; in doubt, 25%
up to 150 mm	25%

What does it do?

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; Which transmission goes with which opening in the Moon filter guide.

Key data

Which variant suits you?

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.

• 13% of 25%: 13% from about 200 mm opening, 25% up to about 150 mm. Between that and the moon phase depends. If you're unsure, use 25%: that works even with a half-moon, where 13% becomes too dark on a 150 mm telescope.
• 1.25 or 2 inch: choose the size of the eyepiece where the filter goes, not the size of the eyepiece itself. If you use 2 inch eyepieces, then 13% 2 inch whether it 25% 2 inch.
• 13% of Premium: it Omegon Premium Moon Filter It fits approximately 30% telescopes and is intended for telescopes up to 150 mm; for 200 mm and more, that is too small.
• Fixed or variable: the variable polarization filter It adjusts infinitely from 1 to 40% and is the choice if you have multiple telescopes or want to adjust for each lunar phase. With just one large Dobson, this fixed filter is sufficient.

Frequently asked questions about the Moon Filter 13%

• Can I use this sun filter? No, never. A moon filter blocks 87% of the light, a sun filter more than 99.99%, and a filter in the eyepiece can crack due to the heat. For the sun, only a filter before the tube is suitable; how it works is described in solar filter telescope.
• Can I use 13% on my 150 mm telescope? Around full moon it works fine; at half moon the image gets too dark. If you have one 150 mm telescope, then use the 25%th version.
• Does it work on planets too? On Venus and Jupiter, it does, because they are bright enough. Saturn and Mars are too dark; you can't see them without a filter.
• Does the filter change the color of the moon? No, the glass is neutral; the moon remains white to light gray.
• What is the difference with the 2 inch version? Only the size of the wire. The same transmission; the 2 inch version goes into 2 inch eyepieces.

Specifications

Shipping and assistance

Which transmission goes with which telescope is stated in the Moon filter guide; more filters of this merk on the Omegon brand page. Orders with multiple items are shipped from multiple warehouses and may arrive in parts; each package will have its own tracking number. Help choosing: WhatsApp or call on business days from 9:00 to 17:00. 30-day return period.