Baader Calcium Filter GEN-II 1¼" with LPFC
GEN-II 1¼" calcium filter with low profile filter cell
The GEN-II calcium filter allows observation of the interesting border region between the photosphere, visible in white light, and the sun's chromosphere, reserved for narrow-band H-alpha filters. In addition to the structures known from white light, such as sunspots, one can see the chromospheric network distributed over the entire surface of the sun, which precedes the formation of sunspots, as well as supergranulation cells and Ellerman pumps.
The calcium emission line at 394 nm is already in the near UV. Therefore, observing the sun at this wavelength is only possible with a camera! Never use this filter for visual observations, as our eye is blind to the harmful UV radiation, but can be damaged by it.
This filter gives the best results when used with a monochrome camera (which is more sensitive in this part of the spectrum than a color camera) and mirror telescopes (because especially refractors with fast f/ratios are not optimized for best sharpness in this part of the spectrum). However, many lens telescopes still work well for calcium observations; unmodified DSLRs may require extremely long exposure times.
All calcium filters require an additional solar filter in front of them. Part of the Baader GEN-II is a sheet of AstroSolar Photo Film OD 3.8, 20x30 cm (#2459278 , € 34) to build a solar filter yourself, so you can start observing without buying any other filters. Of course, you can also use one of the BDSF: Baader Digital Solar Filter OD 3.8 (80mm - 280mm) which are already mounted in a filter cell. In telescopes with suitable objectives, you can also use a Herschel prism. In this way, you can replace the integrated ND3 filter mounted behind the Herschel with a weaker filter to achieve shorter exposure times. These filters are already included in the scope of delivery of the Baader Safety CoolCeramic Herschel Prism 2" Photographic (#2956510P , € 645).
The calcium GEN-II replaces the old 1¼" K-Line filter (stacked) # 2458355. Thanks to modern manufacturing techniques, a single filter now achieves better quality and a narrower half-bandwidth (FWHM) of only 5 nm instead of the previous 8 nm; now it is no longer necessary to stack two filters. This also allows the filter to be used in standard filter wheels/drawers; the low-profile filter mount is only 6 mm high when screwed in.
General features:
- Single filter (no stacking!), shows the finest solar details in calcium K light (Cak)For solar photography only in combination with the attached AstroSolar ND3.8 photographic film or a Herschel prism (sold separately: Baader Safety CoolCeramic Herschel Prism 2" Photographic (#2956510P)
- Enhanced contrast matched to the quantum efficiency and s/n ratio of typical CMOS cameras.
- Reflex-Blocker™ coatings, for maximum immunity to retroreflection from the closest auxiliary optics, even in the most adverse conditions.
- Filter thickness identical to existing standards, with maximum care for homofocality
- Reflex-Blocker™ hard-coated and plano-optically polished - with sealed coating edges (Life-Coat™)
- Blackened edges all around, with filter-side indicator in the form of a black outer edge on the telescope side
- Supplied with AstroSolar ND 3.8 photographic film, size: 200 x 290 mm - for pre-filtering of sunlight
- The Gen-II calcium filter must NOT be used in the light path WITHOUT pre-filtering.
- Visual observation is not possible with the calcium filter, as the eye is virtually blind in this part of the spectrum. Never point the telescope directly at the sun with the calcium filter alone (without an additional attenuation filter).
Technical specifications:
- MANUFACTURER Baader Planetarium
- SKU (#) 2961590
- EAN CODE 4047825048783
- NET WEIGHT (KG) 0.108
- TRANSMISSION RANGE CaK-II
- FILTER THICKNESS (WITHOUT FILTER CELL) 2 mm
- HBW (HALF BANDWIDTH) 5 nm
- CWL (CENTER WAVE LENGTH) 394 nm
- AR-COATING dielectric coating, plano-optical polishing
- SPECIAL FEATURES only for photographic use behind another sunscreen filter
- FILTER SIZE 1 25 in
- Solar filter use
- FILTER MOUNTING Mounted (LPFC 6mm)
- FILTER TYPE Narrow band
- oNE OR SET? Single filter
- FILTER SHAPE round
Baader Calcium Filter GEN-II 1¼" with LPFC
