Antlia U-Venus Filter 1.25 inch

Antlia Venus-U filter is designed for imaging the cloud structure of Venus and Jupiter with CCD cameras on a telescope. Cloud details primarily reflect in the ultraviolet band which cannot normally be imaged using broadband filters. The Venus-U filter uses the latest dielectric interference coating technology to achieve high transmission efficiency and exceptional isolation of the critical UV bandwidths. The filter effectively blocks the contrast damaging frequencies beyond 400nm which typically swamp the ultraviolet cloud details on camera sensors. Like the highest quality Antlia LRGB filters, the U-Venus filter minimizes halos around bright stars and increase the contrast.

Recommendations in the use of this filter:

1. When U-Venus filter is used with a planetary camera, it is recommended to remove any protective UV-IR window in front of a color planetary camera because this filter may attenuate transmittance of the critical ultraviolet band that contains cloud details.

2. The lower the frequency in the UV band, the longer will be the exposure to achieve sufficient signal in your image. The sensitivity of most sensors also decreases rapidly at shorter UV wavelengths.

3. It should be noted that when using DSLR to shoot ultraviolet flowers, the camera needs to be specially modified to remove the infrared cut filter inside the camera.

4. In non astronomical use, the lighting conditions may block UV transmissions e.g. the UV contents of electronic flash emission, because of a combination of lower emission at shorter wavelengths and increased absorption by the glass of the flash tube. These factors combine together to require a substantially increased exposure time (for continuous UV sources), UV intensity and ISO sensitivity as the wavelength decreases.

Non-astronomical applications：

Use for general UV photography (flowers, health of plants,insects, forensics and medical imaging)

Technical Data:

• optical substrate
• Thickness: 1.25” mounted (2mm+/-0.05mm)
• Surface Quality: 60/40 (Refer to MIL-O-13830)
• 2 sides fine-optically polished to ensure accurate 1/4 wavefront
• 30 arcsec parallelism
• Tave＞80%
• OD3（＞0.001）@ 200-1050nm
• 2 sides Dielectric multi-coating
• Single / Non-glued substrate

Filter Ring:

• 1.25”(M28.5*0.6)
• Ultra-thin filter cell to minimize vignetting by maximize possible clear aperture
• Black Anodized Finish
• Laser Engraving No Fading

Notes:

• 1.Using the filter for visual observations is impossible due to the eye's insensitivity to this spectral range (UV).
• 2.This filter is NOT to be used for visual observations, specifically the sun or UV light sources.

When using monochrome (black and white) CCD cameras (like The Imaging Source, ALCCD5, etc) filters are needed to produce dcolor images.

The Astronomik LRGB 4 filter-kit was designed especially for CCD imaging, resulting in true color images, even when taking images with continuum or emission spectrum. This filter set is the best in its class.

The Astronomik Pro Planet 642, 742 and 807 or Castell IR-Pass filters are used to capture images in the near infrared light there atmospheric distortions are less evident, resulting in higher resolution when imaging planets or the Moon. Can be used with excellent results for Moon, Mars, Jupiter, Saturn and other planets.

The ZWO 1.25″ IR 850nm Pass Filter is suitable for IR sensitive cameras. You don’t need to debayer and get the full resolution of this sensor when use it with a color camera such as the ZWO ASI224MC or ASI185MC, because the QE responce  of sensor beyond 850nm is all the same (i.e. infrared light passes through the Bayer colour layer). So you can use a color camera as mono camera with this filter, just don’t forget to keep the WB_R and WB_B settings to 50 (no White Balance applied).