MaxFR filters are optimised for astrophotography with very fast telescopes, such as Celestron RASA optics or the Omegon Pro Astrographs.
For the three most important lines, namely OIII, H-alpha and SII, the series offers filter sets with half-widths of 12nm and 6nm.
The filters provide the best possible out-of-band blocking across the entire spectral range from UV to IR! The advantages are maximum contrast, minimal stray light, no halos and the finest star images. With Astronomik MaxFR narrowband line filters, you get raw data of the highest quality: the optimal starting point for further processing into impressive astrophotography!
For the best possible yield, maximum transmission of the filters is required:
- For MaxFR filters with a 12 nm half-width, this means unrestricted usability from f/1.7 to f/8 and approximately 85% of the maximum transmission.
- For MaxFR filters with a half-width of 6 nm, this means unrestricted usability from f/2.2 to f/8 and approximately 90% of the maximum transmission.
The SII filter is optimised for particularly high-contrast results by not allowing H-alpha and NII (nitrogen) to pass through.
The SII filter increases the contrast between SII regions and the sky background. Due to its narrow half-width and high transmission of almost 100% in the SII line, the filter achieves a significantly greater contrast increase than broadband filters. The half-width of 12nm is optimally matched to the use of typical CCD and CMOS sensors.
Even in large cities, images taken with cooled cameras are usually limited by dark current. Therefore, further suppression of the sky background by lower half-widths does not reveal more details in the object. Compared to very narrow-band filters, the H-alpha 12nm filter has the advantage that you can usually find guide stars for almost all cameras with built-in tracking sensors.
MRF-coating: thanks to the new MFRF coating technology, it is possible to use the filter on all devices up to an aperture of f/4.
Alternative: The line filters with 6nm half-width are interesting if you want to photograph objects in very starry areas of the sky with short focal lengths, if you have a camera with very low dark current or if you are observing from a location with extreme light pollution. The number of stars in the image is typically halved.
A bit of help with your selection:
- As a first filter, we recommend the Astronomik CLS filter. This filter suppresses artificial light pollution and natural airglow. By using this filter you get a dark-sky background and can therefore use much longer exposure times to make fainter objects visible. The filter is optimised in such a way that objects are reproduced in their natural colours. Important: the simple CLS filter has no built-in IR-blocking. Therefore you will need the CLS-CCD filter for an astro-modified camera!
- A good choice for working in locations with really heavy light pollution is the Astronomik UHC filter. The transmission curve of this filter only allows the light of the H-beta, OIII, H-alpha and SII lines to pass through. The background suppression is significantly stronger than with the CLS, however this filter works only for gas nebulae! Star clusters and galaxies are largely filtered out.
- For a more in-depth introduction to astrophotography, we recommend the OIII, H-alpha and SII emission lines filters, available with full width at half maximum of 6nm or 12nm. With these filters you can create detailed images of faint objects even from locations with extreme light pollution and a full Moon high above in the sky. Images in these narrow emission lines are not naturally coloured.
- For the owners of astro-modified cameras we offer the Astronomik OWB filter: OWB stands for "original white balance". The filter corrects the displaced colour reproduction of a converted camera so that it can also be used for normal every-day photography, without having to revise every image on the computer.
