- Research Grade Filter RG 18: 18mm clear aperture, selected quality with extremely uniform H-alpha image over the entire image field
- Halfbandwidth 0.3 +.1/-.05 Ang
- Ideal for imaging
- Heated H-alpha – Filter (lambda = 656,3 nm) with electronic temperature control (heating and cooling combined). 5 years warranty if handled properly
Important note: Requires an additional Energy Rejection Filter (D-ERF) in front of the lens.
18mm clear aperture, extreme filter uniformity for research applications. Available in the following bandpasses - 0.3A.
"I used the solar filter today. WOW!!!!!! The level of detail is incredible. Using a Televue Panoptic 35 I can see the entire disk. Using a BinoViewer with 26mm Meade eyepieces, the field of view is smaller but the image looks almost 3D and is far more pleasing. I am more than satisfied with this equipment. Well worth the cost and the wait." Tony Van Heugten (SO-1.5, 0.3A on a Meade 10" SCT with 90 C-ERF)
Solar Spectrum produces what we have found to be the ultimate in high resolution H-Alpha filter systems. With over 30 years of experience in making filter systems for professionals as well as amateurs, Solar Spectrum brings an unmatched level of expertise to bear in producing filters at prices accessible to amateurs. This experience uniquely enables them to deliver a high level of quality and consistency in very narrow filters (< 0.3A) which are extremely demanding to produce.
These rear-mounted mica etalons deliver high-quality narrowband filtration that can be used with apertures from as small as 40mm up to 180mm! Unlike front objective etalons, the telescope aperture is not limited by the diameter of the etalon. Every Solar Spectrum filter can be flexibly configured to match any desired telescope and aperture desired, without any loss in resolution. Each Solar Spectrum filter system includes the rear mounted etalon assembly (which includes an integrated thermoelectric heater/cooler), programmable temperature control box with digital temperature readout, and AC power cable. The control box accepts 90-256 VAC 50/60Hz. For DC use, any inexpensive inverter can be used. A complete system consists of a Solar Spectrum Filter and Front-Mounted Energy Rejection Filter. Telescopes with focal ratios faster than f/20 will also require a telecentric lens to produce the desired f/25 - f/30 beam. Currently, Telecentric lenses are available in 2X, 3X, and 4X amplifications.
Availability: Currently, we offer Solar Spectrum filters on a special order basis. Typical delivery times range from 12-24 weeks, depending on filter size and bandpass. Occasionally we will have a system available from stock. Please contact us for specifics. Narrower halfbandpasses available on request (primarily for imaging use). Calcium K-Line and custom filters are also available upon request.
Payment: Deposit of 50% required at time of order, remainder due when filter is completed and ready to ship. Payments by check or money order only (sorry, no paypal or credit cards for Solar Spectrum Products).