Skip to content

A full Moon in a large telescope is genuinely too bright

The best Moon filters for 2026

A full Moon seen through a telescope of any size is uncomfortably bright, and the discomfort is not merely aesthetic: a dazzled eye loses the dark adaptation that took twenty minutes to acquire, and the rest of the session suffers for it. A Moon filter dims the disc so that the low-contrast detail near the terminator becomes readable rather than washed out. The plain versions are a single piece of coated glass with a published transmission percentage, and that figure is what should be compared — a filter that passes a quarter of the light and one that passes half are different tools for different phases and different apertures. Cheap filters achieve the dimming with a green tint, which does the job and colors the Moon; a neutral density filter dims evenly and keeps the gray. The more flexible answer is a variable polarizing filter, two polarizing elements in a rotating cell that between them cover a wide range of transmission from a single accessory. It suits an observer following the Moon through its phases, where the right amount of dimming changes week by week, and it works on bright planets as well. Read the thread size against the eyepieces in the case, since these screw into the barrel and the two common fittings differ. Read whether the glass is described as flat and whether the cell adds enough length to foul a short eyepiece barrel. We compare transmission percentage, neutral or tinted dimming, fixed or variable design, thread size, glass flatness and cell depth.

By

The parts here, column by column

  1. Celestron 94107 variable polarizing moon filter

    Celestron Variable Polarizing Moon Filter (94107)

    Celestron's Variable Moon Filter: a two-element polarizing filter for 1.25-inch eyepieces whose transmission adjusts from 1 to 40 percent by rotating its lower ring.

    Transmission percentage
    Adjustable from 1% to 40%, stated
    Neutral or tinted dimming
    Polarizing, neutral
    Fixed or variable design
    Variable: rotate the lower ring
    Thread size
    1.25 in, threads onto any Celestron 1.25 in eyepiece
    Glass flatness
    Not published by the maker.
    Cell depth
    Not published · Amazon's item data gives 16 g
    Amazon reference
    B07N99RW5K
    EAN
    0050234941075
    • Transmission adjustable from 1 to 40%
    • Works on the Moon, Venus and bright double stars
    • Two elements are thicker than a single filter

    Best for: The Moon across its whole cycle, where a fixed filter is right at only one phase

    ≈ $43
    Check price on Amazon
  2. Vixen 1.25 inch moon filter

    Vixen Moon filter 1.25 in (37222-5)

    Vixen's 1.25-inch Moon filter: a neutral density filter equivalent to ND4, which passes about a quarter of the light, with a 19 mm effective diameter, for eyepieces of 31.7 mm.

    Transmission percentage
    About 25%, from the stated ND4 equivalence
    Neutral or tinted dimming
    Neutral density (ND), stated
    Fixed or variable design
    Fixed
    Thread size
    1.25 in (31.7 mm) eyepiece mount
    Glass flatness
    Not published in the Amazon.com listing.
    Cell depth
    0.2 in (5 mm) · 0.7 in (19 mm) effective diameter · 0.4 oz (10 g)
    Amazon reference
    B0018HILMI
    EAN
    4955295372225
    • Dimming factor published: ND4, about 25%
    • Neutral: no color tint
    • About $58 for a fixed Moon filter

    Best for: A 1.25 in eyepiece case where a neutral, known dimming factor matters

    ≈ $58
    Check price on Amazon
  3. Almencla 0.965 inch telescope filter with a metal rim

    Almencla 0.965 in Moon filter

    A 0.965-inch filter for older telescopes, in an aluminum alloy rim, whose listing describes it as a Moon filter, a nebula filter and a set of four, with no transmission figure.

    Transmission percentage
    Not published by the maker.
    Neutral or tinted dimming
    Not published by the maker.
    Fixed or variable design
    Fixed · described both as a Moon filter and as a nebula filter
    Thread size
    0.965 in (24.5 mm)
    Glass flatness
    Not published · glass lens in a metal rim
    Cell depth
    Not published · 6 g
    Amazon reference
    B07VQKLGZ8
    EAN
    0614089427032
    • Fits 0.965 in eyepieces, which few filters do
    • Metal rim
    • Described as both a Moon filter and a nebula filter

    Best for: An older telescope with 0.965 in eyepieces, where almost nothing else fits

    ≈ $20
    Check price on Amazon

Moon filters in brief

  • Most affordable here: Almencla 0.965 in Moon filter, at $20.
  • Highest figure for thread size: Vixen Moon filter 1.25 in (37222-5) (1.25 in (31.7 mm) eyepiece mount).

Comparison table for moon filters

The column is shown only when four instruments in five publish the figure. Below that, it would be comparing the absence of numbers.

ModelPriceFixed or variable designThread size
Almencla 0.965 in Moon filter$20Fixed · described both as a Moon filter and as a nebula filter0.965 in (24.5 mm)
Celestron Variable Polarizing Moon Filter (94107)$43Variable: rotate the lower ring1.25 in, threads onto any Celestron 1.25 in eyepiece
Vixen Moon filter 1.25 in (37222-5)$58Fixed1.25 in (31.7 mm) eyepiece mount

The guides that discuss moon filters

Where the figures are drawn from

Specifications: manufacturer sheets for telescopes and observing optics and the matching Amazon product pages. Prices and availability: Keepa. Every figure in this table names its source.

Most recent revision in this category: November 7, 2026.

The way we judge moon filters

Any figure written into the body of this page was true on the day it was written. The amount shown next to each instrument is requested from the retailer as the page loads, and it is that amount, not the text, that stands.