Used Astronomik OIII 12nm Clip Filter for APS Canon - UT-11945 - SOLD
- This is a used filter in excellent condition
- 97+% transmission for the OIII line
- Blocks nearly the whole remainder of the visual spectrum
- Blocks unwanted wavelengths in the infrared
Used Astronomik OIII 12nm Clip Filter for APS Canon - UT-11945 - SOLDThe Astronomik OIII CCD filter is a narrow band emission-line-filter for CCD photography. The filter lets the light of double ionized Oxygen of emission nebulae pass and blocks nearly the whole remainder of the spectrum where the CCD is sensitive. The full width at half maximum (FWHM) of 12 nm is ideal for common CCD cameras and allows the use of very fast optics. The optimal aperture ratio for the use of the filter is 1:3 to 1:15 with apertures of more than 6" (150 mm). It should be noted that the filter has a transmission of up to 99%, which cannot be attained by stacking more narrow-band filters. A further note, which led to selecting the half width (FWHM), is the dark current of common CCD imagers. Exposures with a CCD cooled to -15°C are limited by the dark current of the CCD, even in large cities with a bright background. Another advantage of the 12 nm filter is the better availability of guiding stars for cameras with built-in-autoguider.
The Astronomik OIII CCD increases the contrast between objects, in this case between the OIII emission line and the skyglow background. Our Astronomik OIII CCD completely suppresses the emission lines of artificial lighting (mercury (Hg) and sodium (Na)) and skyglow. Transmission losses and chromatic distortions, which arise with other filters, only occur with Astronomik filters when extremely bright aperture ratios of 1:2 and more come into play. The filter has a built-in IR-blocker up to 1150 nm. You don’t need an additional IR-blocker with this filter.
When using the Astronomik OIII 12 nm CCD - EOS Clip filter together with the H-alpha, and the SII CCD filters you can obtain three-color images of emission line objects (gas nebulae) from locations with very strong light pollution. To do so, you would take an image in three different wavelengths, select each one as a color-channel in Photoshop and paste them together as one single color image. Diffraction limited, the filter will not reduce the optical performance of your telescope! Astronomik filters are delivered in a high-quality, long lasting, plastic filter box.
- Astronomik OIII 12nm clip filter
- Protective plastic case
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