Baader 2" f/2 Highspeed Filter Set
The 2-Inch f/2 High-speed Filter Set by Baader Planetarium:
Baader's new f/2 High-speed Narrowband filter sets contain H-alpha, OIII, and SII filters and are made specifically for the sensitive requirements of exceptionally fast astrograph optics, such as HyperStar, RASA, and extremely fast instruments from TEC, AP, ASA, etc. Ordinary narrowband filters generate a heavy loss in transmission because of the strong CWL (center-wavelength) shift. In severe circumstances, the CWL even shifts out of the FWHM (full width half maximum).
As a result, these filters have a CWL-preshift which flawlessly matches f/2 to f/3. Furthermore, the FWHM is enhanced. Despite the typical line broadening with such fast optical trains, these filters are still able to produce peak contrast. These filters permit the effective use of tremendously fast optics for maximum contrast imaging of emission nebulae for the first time. Compared with a regular set of narrowband filters, using these high-speed filters between f/1.8 and f/3.5 will exhibit drastic improvement.
OPT Product Number: BA-FHSS-2
Questions & AnswersAsk a Question
Do these filters also work well at lower speeds (e.g., 5.6,7,10), or is their performance inferior to non high speed filters at these more typical focal ratios?
The bandpasses of the high speed filters are "pre-shifted" somewhat for ~f/2 and so they are less efficient (lower transmission) at slower focal ratios as they go slightly "off-band."
Are all these filters parfocal?
These filters use similar substrates and glass thicknesses to be as close to parfocal as possible. But due to manufacturing tolerances and a having very shallow plane of focus (because of focal ratios being between f/2 and f/3) there will most likely be a