Astronomik SII 6nm CCD Filter MaxFR Clip-Filter EOS APS-C

Do you own a Canon EOS digital camera for astro-imaging? Then you have surely encountered the following problems:

• Large filters for large camera lens objectives are very expensive
• If you place a filter holder between your camera body and lens you loose the ability to focus to infinity
• For very fast (low f/ number) telescopes like the Vixen R200SS or the Takahashi Epsilon astrograph, a filter drawer or a filter wheel cannot be used since the distance to the corrector lenses would be changed.
• With long exposure times your cameras sensor chip is exposed to more dust

With the Astronomik Clip-Filter System you can take care of all of these problems at once!

The patented Astronomik Clip-Filter System is black anodized aluminum and laser-cut on state-of-the-art modern machines. It can be inserted within seconds directly into the EOS camera body. There are no changes necessary and all lens functions (focus, screen, image stabilization) remain functional!

Almost all Canon system lenses (with the exception of the EF-S series) and all M42 and T2 lens adapters, can be used with the Astronomik Clip-Filter System. The Clip-Filter System also acts as an outstanding dust shield, which prevents the possibility of dust settling on the sensor during long time exposure (The MC-Clear filter does not have a filter effect and only acts as a dust shield.)

List of compatible Canon EOS cameras:

Important: Not suitable are cameras offered before 2003 and all varieties of the Canon EOS 1D and EOS M.

This SII-CCD Filter is suitable for imaging of SII-regions from observation sites with light pollution and from dark sites as well. The contrast between an object glowing at 672nm and the background is increased enormous!

Due to the combination of the narrow bandwidth of 6nm and the high transmission of typically 96% the filter gives you an enormous contrast boost, as all unwanted light from other wavelengths than 672nm is blocked form UV up to the IR. This results in an extremly dark background.
The FWHM of 6nm is matched to give you optimal performance with CCD and CMOS sensors with a very low dark current! The 6nm filter is the best choice if you are observing from a heavily light polluted site or if you are imaging faint objects in starcrowded regions of the milkyway.

Due to the new MFR coating technique you may use one single filter on all instruments up to f/4 without a significant reduction in performance.

Technical data of the filter:

• Guaranteed Transmission of more than 90% at both SII lines (671,7nm und 673.0nm)
• Typical Transmission of 94% at both SII lines (671,7nm und 673.0nm)
• Full-Width-Half Maximum (FWHM): 6nm
• perfect blocking of unwanted light from UV up to the IR
• parfokal with all Astronomik filters
• MFR Coating technique: Usable with all optics up to f/4
• Thickness of 1mm
• Not sensitive to moisture, scratch resistant, not aging
• opticaly polished substrate, striae-free and free of residual stresses
• High quality storage box

Imaging with Narrowband-Emissionline Filters
If you have to observe from light polluted sites (like most of us...), imaging with Narrowband-Emissionline filters is the best way to take great images, as all kind of light pollution can be blocked very effective! Normaly an H-alpha filter should be your first step into this amazing field of astrophotography! With an Narrowband H-alpha filter you will be able to take deep and contrasty images even wih very heavy light pollution or with the full moon high up in the sky!
If you look at other astrophotos, an H-alpha is the best choice for all nebulas glowing red! An OIII filters expands your imaging possibilities, as you are able to image all greenish/blueish structures. Planetary nebulas and star forming regions are great targets! The SII filters completes your HSO-set of filters. With these three filters you are able to process your images like the ones from the Hubble space telescope!
The h-beta filter is not available in a 6nm version, as this filter has nearly no meaningfull application. To illustrate this, there are two images shown below: Both were taken with a unmodified Canon 650D. Even as the camera has a sensitivity of less than 10% at H-alpha, there is some signal und structure in the h-alpha image, while you cannot see anything on the image taken with an H-beta filter!

Operation of the filter:
The filter blocks all unwanted light from artifical light-pollution, natural airglow and moonlight. Especially light from High- and Low-Pressure Sodium and mercury lights and all lines of natural airglow are 100% blocked. The filter increases the contrast between the sky-background and objects glowing at the xx line at xy nm.

Tips and Hints for more applications:
Using the xx filter together with OIII-CCD and SII-CCD filters you make produce false-color emission line images (HSO) in the same way as the Hubble-Space telescope. This is possible even from heavyly light polluted sites!

Alternatives:
The lower priced 12nm filters are the right choice for you, if you own a typical DSLR or a CCD camera with a high dark current! The 12nm filters should be the fist choice for cameras with an integrated guiding sensor, as you will have about twice as much stars compared to the 6nm filter.