Astronomik OIII 12 nm CCD Filter - 50 mm Round - OIIICCD-50R

• The Astronomik OIII 12 nm CCD Filter has been designed specifically for astrophotography and is presented in a round, 50 mm cell
• Close to full transmission in the OIII line
• 12 nm FWHM bandwidth
• An ideal filter for imaging planetary nebulae and supernova remnants
• Astronomik OIII CCD Filter coatings provide superior protection from blemishes caused by scratching, aging, and high humidity
• This filter is diffraction limited and therefore will not lessen your telescope's optical performance
• German-made for superior quality optics!
• Enhanced for telescopes with an aperture of 6" or more

This Astronomik OIII CCD Filter is a narrowband emission-line filter, expressly designed for CCD astrophotography, with a 12 nm FWHM. It lets double ionized oxygen from emission nebulae pass through while, at the same time, blocking nearly 100% of the remaining spectral areas where the CCD is more vulnerable. The 12 nm full width at half maximum (FWHM) allows for extremely fast optics to be used with common CCD cameras. For telescopes with apertures over 6" (150 mm), 1:3 to 1:15 is the ideal focal ratio range. It should also be acknowledged that this filter's transmission of up to 99% cannot be achieved by stacking extra narrowband filters. Furthermore, with regards to the dark current of typical CCD cameras, exposures with a CCD cooled to -15°C are limited by the dark current of the CCD, even in large cities with strongly illuminated backgrounds. This led directly to the 12 nm selection. Another benefit of this filter is the increased opportunity for finding guide stars with imagers that have an integrated autoguider.

Highlighting the contrast between OIII emission line objects and the background sky, the Astronomik OIII CCD Filter provides complete suppression of spurious light sources such as mercury (Hg), sodium (Na), and skyglow. Loss of transmission and color distortions, while a nuisance with filters from other brands, only becomes a problem with this filter when ultra bright aperture ratios of 1:2 or more are used. Since the Astronomik OIII 12 nm CCD Filter has a built-in IR-blocker up to 1150 nm, extra IR blocking filters are not required.

Employing a combination of this filter with an H-alpha or SII CCD filter allows for the production of three-color images of emission line gas nebulae, despite any heavily light-polluted environments. For this, you would need to utilize Photoshop to combine an image taken in three different wavelengths by choosing each as a separate color-channel and pasting them together. The Astronomik OIII CCD Filter is diffraction limited to preserve the optical performance of your telescope. Astronomik filters arrive with a long-lasting, high quality plastic storage container.

• 99+% transmission for both of the OIII lines
• Blocks unwanted wavelengths in other areas of the visual spectrum