Baader U-Filter (Venus), 1.25"
Another unique and pioneering filter from Baader Planetarium. For the first time, amateurs can now record cloud structures on Venus. The Baader Venus Filter enables amateurs to successfully image in the deep UV, a spectral region normally inaccessible.
The latest coating technologies permit the Baader Venus Filter to transmit from 300nm to 400nm, with a peak transmission of 80%. The filter completely blocks the rest of the region from 200nm to 1500nm, through the use of a complex 20 layer dielectric coating stack, on top of a special optically polished UG-11 substrate. Up till now, Amateur efforts typically relied upon deep violet colored filters, or combinations with simpler interference filters, which do not provide the high transmission and efficient rejection outside the important spectral region from 320nm to 390nm. Given the poor transmissions of many optics in the UV and the lower sensitivity of some CCDs to this wavelength, high filter efficiency and complete rejection at longer wavelengths becomes paramount to recording good contrast at reasonable exposures. The same high optical quality and features as the other Baader filters ensures the highest contrast and sharpest images possible.
Interestingly, the solar Calcium K-Line is also within the pass band of this filter. This opens up the exciting possibility for recording flare structures on the solar disk or edges.
The Baader U Filter has become the choice of UV imagers exploring the UV world of landscape, floral, and even forensic imaging. The latest 2" filter now has even higher transmission and improved out of band blocking. By using our DSLR-2 filter adapter ring plus the appropriate filter step ring (HDT-Rings), UV imagers can conveniently mount the U-Filter to their camera lens.
Here are some useful and interesting UV sites with some nice images of flowers and information on UV imaging. From there you can also link to many other UV sites:
Please Note: The Baader Venus filter is only applicable for imaging of Venus with Webcam, Digital, and CCD cameras (Visual Observation is impossible, due to the eye's insensitivity to the UV). For successful Venus imaging, we recommend the use of a UV sensitive astro CCD camera (ie, SBIG ST-2000XM) and at least a 5" telescope, or a webcam and 8" telescope.
Please click on the image below for a typical transmission curve:
- Baader Venus Filter, 1.25” (#FUV-1) NEW
- Baader Venus Filter, 2” (#FUV-2)