Astronomik H-alpha filter with a half-width of 6 nm in the frame 1.25 "/ 31.7 mm.
The H-alpha filter is a suitable filter for photographing hydrogen nebulae from both light-contaminated areas and under dark, rural skies. Increases the contrast between the glowing object on the 656 nm line and the background.
The combination of a narrow bandwidth of 6 nm and a high transmission of typically 96%, the filter provides an extraordinary jump of contrast, since all unwanted light from other than the 656 nm band is blocked, from UV to IR. Thanks to this, a very dark background is achieved.
FWHM (half-width) equal to 6 nm guarantees the best results with CCD and CMOS matrices with very low dark currents. 6 nm is the right choice for people watching from areas that are very polluted with light and for people photographing weak objects in those areas of the sky where there are a lot of stars (mainly in the Milky Way).
• blocks all unwanted light - artificial pollution with light, natural light of the atmosphere, moonlight; in particular, it blocks sodium and mercury lines
• using H-alpha filters together with O-III and S-II you can get a color photo consisting of three emission lines (HSO) in whole, even when shooting under extremely bright skies, eg in the center big city
• users photographing a SLR camera or CCD camera with a high dark current should choose a filter with a FWHM of 12 nm or more.
• a filter designed for shooting with devices with a light to f / 4; with a larger light (eg with bright lenses f / 2), the filter will not work optimally (reflections).
• the filter is not intended for observing the Sun.
• guaranteed transmission above 90% for the H-alpha line (656 nm)
• typical transmission for H-alpha lines is 96%
• half line width (FWHM): 6 nm
• blocks the remaining wavelengths from UV to IR
• parchocal with other Astronomic filters
• MRF layers
• thickness: 1 mm
• resistant to moisture, scratch, does not age, without residual material stress