Astronomy Filters

Our business began in 1990 as research astronomers came to us to obtain high-performance, high-precision telescope filters and optics. This was driven in part by the emergence of CCD imaging. At that time it was only large research institutions that could afford the $200,000 + costs associated with custom-building of such large format, digital cameras. Over many years, we perfected our skills and techniques in designing and manufacturing filters that are optimized to function with CCD cameras.

In the mid and late 1990's, as the costs of off-the-shelf CCD cameras dramatically declined so that amateur astronomers could own them, too, we found that those amateur astronomers were also coming to us to obtain high quality filters, just as their researcher "cousins" did. In response to that, we developed and stocked a series of commonly used filters. Although such filters when built for a research astronomer could cost thousands of dollars, by mass production techniques and minor changes in design we were able to lower prices often by more than half.

All of our astronomical filters have IR blocking "built-in" so IR light does not contaminate today's sensitive CCD detectors. When you use filters from Custom Scientific, you do not need any additional IR blocker filters. One exception is in the thickness-matched Clear filters which transmit all wavelengths from the UV to the far IR; they are clear, high-precision, optical windows designed to transmit all wavelengths of light without having to refocus when switching back to a color filter.

The filters offered below are the most commonly-used filters by research astronomers on a limited budget, by astronomy teachers, and by serious amateur astronomers. We also routinely make custom optical filters in other sizes and wavelengths, some of which can be seen on our research astronomy page. We also do custom filters tuned for fast (low focal ratio) telescopes and Doppler shifted emission lines. Please contact us to request a quote.

Wide Band Astronomy Filters

Description 1.25" dia. mounted 50mm dia. unmounted
50 x 50 mm square

RGB & Clear Filter Set
$495
$810
$1900

Luminance Filter (IR-blocked Clear)
$95

$150

$195

Johnson/Cousins/Bessell Filters (UBVRI)
$175 per filter
$295 per filter
$500 per filter

Clear Filter for UBVRI
$90

$225

Neutral Density Filter (ND 2, 1.0%T)
$150
$225

*Narrowband Astronomy Filters*
Description	1.25" dia. mounted	50 mm dia. unmounted	50 x 50 mm square
Hydrogen Alpha* 656.3/4.5 nm	Contact us for price.
Hydrogen Alpha* 656.3/10 nm	Call	Call	Call
Red Continuum 645/10 nm	Call	Call	Call
[Oxygen III] 500.7/4.5 nm	Call	Call	Call
Green Continuum 510/10 nm	Call	Call	Call
Hydrogen Beta 486.1/4.5 nm	Call	Call	Call
Blue Continuum 475/10 nm	Call	Call	Call
[Sulphur II] 672.4/4.5 nm	Call	Call	Call
Methane 889/18 nm	Call	Call	Call
Multiband: H-alpha, [OIII], & H-beta	Call	Call	Call
Spanner Tool for unmounting 1.25" filter	$10	-	-
Optics Cleaning Kit	$99	-	-

* For nighttime use only. NOT for solar viewing.

Custom sizes are also available. Contact us for pricing.

All filters have anti-reflection (A/R) coatings.

Narrowband filters are also useful for capturing high resolution images in cities and other areas with high contamination by unwanted light. Thus, they are effective light-pollution filters.

Typical filter spectra

Hydrogen alpha 656.3/4.5 nm*	Hydrogen alpha 656.3/10 nm*
Hydrogen beta 486.1/4.5 nm	[Oxygen III] 500.7/4.5 nm
[Sulphur II] 672.4/4.5 nm	Johnson/Cousins/Bessell Filter Set
RGB Filter Set	IR-blocked Clear (Luminance)
Neutral Density 2	Multi-Band Hα (656.3nm), [O III] (500.7nm), and Hβ (486.1nm)- One filter, 3 emission lines.