1. Photometric Filters 

"Historically our Solid-State Photometers used custom filters designed to transform well to the Johnson photometry standards with our detectors."

UBVRI filters are not for astrophotography. In fact, they are used to do photometry. So it’s in a more scientific application. In photometry, you measure the light coming from a star. By calibrating the data with reference stars, we’re able to get precise measurements on the flux coming out of a star. Combined with a measurement of the distance of the star (that is usually found by satellite to have precise measurements of far stars), we’re able to find fundamental parameters of the stars. Those fundamental parameters are usually the mass, the radius and the temperature of the star.

Main Use and Performance

UBVRcIc filters are not for astrophotography.

WARNING: The filters of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.

Technical Data

• Optical glass fine material
• Spectrum: 300-1000nm
• Surface Quality: 60/40 (Refer to MIL-O-13830)
• Fine-optically polished to ensure accurate 1/4 wavefront and < 30 seconds parallelism over the both surfaces
• High transmission at major nebula emission lines (i.e. H-alpha 656nm, OIII 496nm&500nm, SII 672nm and H-beta 486nm).
• Precision off-band blocking, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm).

This filter set represents the Johnson-Cousins UBVRI photometric system, an extended version of the Johnson UBV system. high transmission at pass-band (a bit lower for U) quality glass substrate, quality finish (fine-optically polished), quality coating comes with protective box for each filter Each filter comes with a plastic case with high pressure EVA case lining. Substrate: High-quality optical glass Surface Treatment: Fine-optically polished Surface Polish Quality: 60/40 (Refer to MIL-O-13830) Surface Quality: 1/4 wavefront Transmission: more than 70% for U, more than 90% for the other four pass-bands Cell: 2" filter cell

Optolong UBVRI photometric Filter Set - 2" mounted This photometric UBVRI filter set includes five 2" round mounted filters: ultraviolet (U), blue (B), visual (V), red (R), and infrared (I). The Optolong 2" UBVRI Filter Set is made with quality brand 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 filter set is designed to be used in filter wheels and filterholders that accept 2" round mounted filters. Quality Filter Materials: Quality brand substrate material from Germany, 1.85 mm thick Multiple layers of anti-reflection non-cementing coatings applied via electron-beam gun evaporation with ion-assisted deposition Quality Finish Filter substrate is fine-optically polished to 1/4 wave and <30 arc seconds deviation from parallelism over both surfaces. Surface quality, according to MIL-O-13830, is 60/40 Optolong´s planetary rotation system is a homogenous and precise coating procedure that ensures both high transmission of pass-band and optical density of off-band