astrodon - Venus Filter 50 mm dia. Unmounted

Astrodon introduces a breakthrough in UV filters for CCD imaging. A  durable,
hard--coated UV filter of the highest quality having the best transmission
available. 
    * Image the cloud structure of Venus and  Jupiter with CCD cameras on a telescope
    * Use for general UV photography  (flowers, insects, forensics)

The Astrodon-Schuler UV filter has traditionally been used for imaging Venus.  It is made from several
colored glasses, but only transmits ~ 65% of incoming UV light in the 300 - 400 nm region. 

Another vendor recently discontinued a 1.25" mounted UV filter due to NIR light leakage, but offers a
2" unmounted version that only reaches 80%T. Astrodon offers you both sizes and higher performance.

Like our highest quality Generation2 Astrodon LRGB filters, the UVenus filter eliminates halos around
bright stars by having the bandpass coating on one side, and a superior broadband, anti-reflective A/R)
coating on the other. 

Astrodon UVenus filters are guaranteed to achieve >90% transmission. The actual scan below has an
average transmittance of 98.2% from 325 - 381 nm, while minimizing out-of-band light leakage.  This
outstanding performance saves you time when imaging weak UV signals, while providing high contrast due
to low light-leakage.

You do not need a separate filter to block the NIR with the UVenus filter.

Specifications

    * 1.25" mounted and 49.7 mm diameter unmounted
    * 3.000+/-0.025 mm substrate thickness
    * Single, striae-free fused silica substrate
    * 1/4 wave substrate prior to coating
    * < 0.5 arcminute parallelism before coating
    * Hard coated to edge
    * Guaranteed to > 90%T peak transmission (>94% typical)
    * <0.01%T 285-305 nm; <0.1%T 420 - 1100 nm

WARNING!

This filter is NOT to be used for visual observations, specifically the sun or UV light sources.