- 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 ...
Astrodon Photometric Johnson-Cousins Ic Filter - 1.25" Threaded Cell - IC-27R
About Astrodon Johnson-Cousins UVBRI Filters
Astrodon filters are high performing, durable filters that provide significant aid for astrophotography and research pursuits. Each filter is constructed using a highly innovative process with a single high quality 3 mm thick fused silica substrate and full hard oxide sputtered coatings. Optimally equipped to provide consistency for long-term research undertakings, Astrodon UVBRI Photometric filters are fully coated and use no colored glass. Featuring the highest throughputs on the market, these filters are able to improve signals and enhance faint detail in deep sky objects.
Astrodon Photometric UVBRI Filters Highlights
- Provides the highest possible transmission for fainter targets
- Contains hard-oxide coatings with no V filter fogging for added durability
- A/R coating and construction is included to reduce halos around stars
- Does not rely upon discontinued colored glass
- Includes Ic (the c is for Cousins) filter with required 900 nm cut-off coatings
- Proudly manufactured in the USA
Astrodon Johnson-Cousins UVBRI Filters - Additional Information
UVBRI filters have long set the standard for photometric measurements. As technology has evolved, so have these filters. In the early 1990s, following initial designs in the 1950s by H.Johnson, and the 1970s by A.W.J. Cousins for photomultipler tubes (PMT), these filters needed to have colored glass selected for them that would match Johnson-Cousins CCD camera designs of the period. But since some of those glasses have been discontinued in the interim, colored glass cannot be used. And since modern CCDs are sensitive to 1100 nm as opposed PMTs of the time that restricted light over 900 nm, it is essential that the dielectric coating used blocks light past 900 nm for modern CCD systems.Internal light absorption in colored glasses once meant the final throughput would be dictated by the limits of traditional filters. Take the UV filter for example. Maximum transmission for a traditional UV filter designed using colored glasses typically does not exceed 60-70%. In contrast, Astrodon Photometrics filters with 100% coatings top 95%. The introduction of hard, durable, and highly efficient dielectric coatings have made over 95% peak transmission as well as stability for consistent extended research possible. Compared to earlier versions, these filters have a longer lifespan while transmitting more light.