- Fast Shipping, Same or Next Day: You made the commitment to purchase, now you want that new item fast, we get it! At High Point all in stock orders ship within 24 hours, pending internal credit card approval.Read more ...
- Unlimited Tech Support Forever: One of the many perks of being a High Point customer is that you get access to our tech support team forever! We are astronomers at heart and truly enjoy helping fellow amateurs achieve success in the field! Read more ...
- 30 Day Return Policy: Ordered the wrong product? Don't worry, we'll take the majority of our products back within 30 days of the purchase date.We want to get you into the observing setup that bests fits your needs. Read more ...
- Guaranteed Price Match: Call or email us if you find a better price on a product! Provide a link for our team to confirm the price and within a matter of seconds you'll have a price match providing the re-seller is within the USA and authorized by the manufacturer to sell the product of interest. Read more ...
- We're Your Connection To The Manufacturer: In the event there is a warranty issue with a product purchased from High Point, we will serve as the liaison between you and the Manufacturer. The net result is faster, more attentive service from the Manufacturer and an enhanced customer experience. Read more ...
Optolong H-Alpha 7nm CCD Filter - 31mm Unmounted - HAL7-31U
Optolong H-Alpha CCD 7nm Filter - 31mm Unmounted
The Optolong H-Alpha 7nm is an extremely narrow emission-line filter that works by allowing a 7nm bandwidth of light, centered on the 656nm wavelength through, and blocking the transmission of contrast-killing light pollution wavelengths. Wavelengths that are responsible for natural light pollution, or skyglow, are drastically reduced, as is artificial light pollution caused by high and low pressure sodium vapor and mercury vapor lights. The result is a high contrast image that reveals the H-alpha line in all its glory.
This Optolong H-Alpha filter will provide the ultimate in contrast between the skyglow background and H-alpha emitting objects, but because it has a FWHM of just 7nm, you won’t see as many stars in the final image as you would with the Optolong 12nm H-Alpha Filter. Use this filter alone for CCD or DSLR imaging, or use together with OIII 6.5nm and SII 6.5nm filters to get a tricolor image of gaseous nebula from light polluted skies. Like all Optolong filters that are designated as “CCD”, this H-Alpha filter also blocks infrared wavelengths from 700nm to 1100nm so you don't need a separate IR-Cut filter.
The Optolong 31mm Unmounted H-Alpha 7nm Filter is made with Schott glass that has been multi-coated with an ion-assisted deposition technology to ensure scratch resistance and stability on the central wavelength, or CWL. This ultra narrowband 7nm H-alpha filter is designed to be used in color filter wheels that accept 31mm unmounted filters.
Please Note: This h-alpha filter is NOT for use on the Sun. To do so could cause irreparable eye damage or blindness. Don’t even think about it!
Quality Filter Materials:
- Schott B260 substrate material from Germany, 2.0mm thick
- Multiple layers of anti-reflection non-cementing coatings applied via electron-beam gun evaporation with Ion-assisted deposition
Optolong Filter Manufacturing Processes and Parameters
- Filter substrate is fine-optically polished to 1/4 wave and <30 parallelism over both surfaces
- Surface quality, according to MIL-O-13830, is 60/40
- 80% transmission at H-alpha 656nm
- Infrared wavelength of 700-1100nm is cut off
- 0.1% transmission Hg at 435nm and 578nm
- 0.1% transmission Na at 589nm
- High value transmission of pass-band and optical density of off-band is assured through Optolong’s planetary rotation system, a homogenous and precise coating procedure
- Each filter comes with a plastic case with high pressure EVA case lining
Optolong is the Astronomy Filters division of Yulong Optics, an optical filter design and processing company out of Kunming, China that has provided filters for over 700 optical companies since 1999. All Optolong filters pass European Union RoHS requirements and have been certified by TUV Rheinland and Bureau Veritas.