Baader D-ERF Energy Rejection Filter 90mm
Product.Nr.:
BP#2459242D
Manufacturer: Baader Planetarium
455,00 EUR
incl. 19 % VAT
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- delivery time : 3-5 Tage
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product description
W A R N I N G
Looking at or near the Sun will cause instant and irreversible damage to your eyes, including blindness. Eye damage is often painless, so there is no warning to the observer that damage has occurred until it is too late. Do not point a telescope or its viewfinder at or near the Sun. Do not look through a telescope or its viewfinder as it is moving.
The full aperture of any instrument that is pointed at the sun must be covered with a proper solar filter or filter/mask combination.
Children and Visitors should be supervised by an adult at all times when partaking in solar observation. Otherwise, keep solar equipment out of a child's and visitors reach to avoid accidental injury.
CAUTION!
"Baader C/D-ERF Filters" are used only for Hα solar observing together with telescopes
which are equipped with a "Solar Spectrum" Hα filter! Never directly look at
the sun through a telescope which has only the C-ERF filter mounted as protective
device. Severe eye damage may occur!
Please read all manuals before use!
Baader has introduced a new evolution in their premium energy rejection filters, from 70mm up to 180mm! These filters incorporate a new all-dielectric IR rejection coating that eliminates the heating from IR energy to produce a truly cold focus (hence, "Cool ERF"). As a result, the telescope and etalon remain cool and safe from excessive heating. The result is longer filter life, and freedom from tube currents caused by heating. Users with compound telescopes (SCTs, Cassegrains, Maks) will really appreciate the D-ERF, due to its reduced heat load on the mirrors and the reduction in tube currents caused by internal heating.
Unlike every other ERF produced up until now, the Baader D-ERF are produced from a high quality optical clear glass, ensuring freedom from the internal impurities that caused so much headache in producing the older red-glass ERFs. The red glass used in producing the older generation of ERFs is of very poor and variable internal quality. In order to produce ERFs from red glass, Baader had to complete and polish each ERF, then interferometrically inspect every one for internal defects, resulting in having to dispose of far more ERFs than they were able to keep. Its no wonder why other red glass ERFs have such a poor reputation, particularly in sizes over 3" in aperture.
The energy rejection is now accomplished using ultra-hard dielectric coatings on both sides of the glass substrate (28-layer dielectric DWDM-coating), and also serve to protect the glass, making it highly resistant to scratches. Baader D-ERF filters are made from high grade optical glass which is free of any internal defects. The thick substrates are polished plane-parallel, smooth, and flat to an amazing 1/10 wave p-v over the entire surface. Only by using thick substrates can a high surface accuracy be achieved and held in use (for example, the 90mm ERF is 5.5mm thick. Thinner substrates are not capable of holding such high surface accuracy). The special dielectric filter stacks are precisely balanced on opposite sides to maintain the superb optical flatness after coating.
Please note: The Baader D-ERF has to be mounted at the front end of the telescope with the blue shimmering side facing the sun!
- With IR-Cut
- 28-layer dielectric DWDM-coating
- Planeoptically Polished (1/10 Lambda)
- Sizes: 90mm
- Thickness: 6mm
- Made in Germany
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66,00 EUR
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Nicht auf Lager
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