-
True Optical Quality: Baader glass substrates are of true optical quality. Most other filters are merely made from raw flame-polished, "optically flat", or sometimes use a top quality commercially polished filter glass (fine for camera filters), resulting in wavefront deformations that damage image sharpness and contrast when used with telescopes. Baader Planetarium filters are made from striae-free substrates, and actually fine optically polished flat to within 1/4 wave p-v over the entire surface, plane parallel to within 30 seconds of arc! This important and unique custom step adds cost - but the result is a filter that maintains the full wavefront quality of the telescope without double images or ghosting, even at high magnifications. Critical to maintaining this level of flatness are Baader's carefully balanced coating designs, which prevent coating surface stresses from warping the substrate. Such high flatness enables Baader filters to be used far in front of the focal plane, ahead of star diagonals, and digital cameras. They are particularly well suited for attachment to the nosepiece of the Maxbright Binocular-Viewer (other manufacturer's filters must be used in pairs, attached right at the eyepieces).
-
Filter Durability: Filter durability has always been a hallmark of Baader Planetarium. The multi-layer dielectric coatings are plasma assisted and Ion beam hardened using the latest technology (the coatings are harder than the glass substrate itself!). Baader filters withstand repeated real-world exposure to the elements and physical cleaning. Users need not leave their precious filters dull and dust encrusted to avoid cleaning - Baader filters may be used and cleaned without fear. We have heard sad stories from owners of other less durable filters, who have seen their coatings degrade from normal exposure to moisture, or wiped away from routine cleaning. Some manufacturers of astro filters resort to coating large sheets of bulk glass, then literally cutting or breaking their filters from the precoated sheets, ripping and tearing the coating's edges in the process - leaving the edges susceptible to moisture penetration and coating peel. This literal shortcut gives a manufacturer the ability to reduce stock and easily produce filters on demand or to readily produce odd sizes, but it comes at the expense of the customer by producing an inferior filter with greater risk of coating failure. Other filters are produced by sandwiching their delicate coatings in between two layers of glass (and risking blurred double images as well as eventual degradation from the edges inward). Baader Filters will truly last lifetimes. Though we don't recommend trying this yourself, Baader filters have passed rigorous military durability tests that subject the filters to boiling water for several hours, then comparing spectral traces before and after. The Baader filters pass this test with no coating degradation.
-
Freedom from Ghosts and Halos: Baader Planetarium's filters have always been halo and ghost free. Baader balances each dielectric coating stack to avoid the ghosts and annoying halos that plague other mfgr's filters.
-
Stackability: Unlike most other filters, Baader Planetarium filters are truly designed to be stacked and combined. This is possible due to the high optical quality and highly efficient anti-reflection multicoatings. The ability to combine filters opens up many interesting possibilities, permitting unique spectral characteristics unachievable with any single filter.
-
Special Filter Cell: Baader's special filter cell design offers unique features that enhance their reliability and usability. Though difficult to produce, the ultra-thin filter cell results in the maximum possible clear aperture, in order to minimize vignetting (1¼" Filter clear aperture is 27mm!, 2" Filter aperture is 45mm). The special threading has been designed to fit the wide variety of eyepieces and accessories (there is significant variation between the 1¼” filter threading used by eyepiece and accessory manufacturers). The front 'crown' of the filter incorporates milled notches which make handling and threading the filter a more secure operation in the dark.
- Low cost: It has always surprised us to see the exorbitantly high prices for some 'premium' filters offered by other manufacturers. Evidently, these prices endure due to mis-perception that higher prices imply higher quality or discernible higher performance. Fortunately, that perception is absolutely false. Despite the highest optical and coating quality in the industry, and use of leading edge German coating technologies, Baader Planetarium filters remain affordable for the amateur. By leveraging high volumes across all filters in the Baader family, these filters can be offered at very reasonable prices (and with a clear conscience...).
For further detailed information on Baader's Unique filters and cells, please click on the following image:
