Secondhand & Stock

The Altair 395nm NUV filter selectively passes light of the two main Calcium wavelengths emitted by the sun: CA-K line at 393.37nm, and the CA-H line at 396.85nm. A specially developed multilayer interference coating results in transmission of approximately 75% at 395nm NUV wavelength. Bandwidth is approximately 7nm (FHWM), resulting in extremely high contrast in the selected wavelength with efficient blocking of unwanted wavelengths. Remaining UV and IR light between 400-1100nm is blocked at OD3 0.1%, and visible light between 400-700nm at OD4 0.01%. Imaging the sun: The filter is to be placed in front of a high speed CMOS video camera for displaying detail in the upper solar atmosphere, at the boundary between the photosphere and the chromosphere. Structures which cannot normally be seen by the human eye or cameras are revealed, including fast-evolving Ellerman bombs (micro-flares) and Plages, (bright networks near sunspots). Solar granulation is also enhanced, as well as umbral detail around sunspots. Imaging the planet Venus: The planet Venus also benefits greatly from higher contrast in the upper cloud layers, showing features normally invisible in white light. The high transmission allows fast frame rates. IMPORTANT: The 395nm wavelength is harmful and almost invisible to the eye, therefore the NUV filter is intended for photographic use ONLY. A pre-filter of at least OD3.8 is required to reduce radiation damage to the filter. A Herschel Wedge, such as the Altair Imaging-Ready Solar Wedge can be used, or solar film, provided the manufacturers instructions are followed correctly. Refractors are usually employed for solar imaging, however reflectors can be used, provided they have a large blocking filter over the front aperture (usually solar film or glass filter because Hershel Wedges cannot be used with reflector telescopes). Imaging requires a monochrome CMOS camera. A typical example with false colour and selective contrast processing is shown opposite (HDR filter, Photoshop). Specification: NUV transmission band, CWL 395nm FWHM 7nm Filter substrate: 1.85mm thick BK7 optically polished glass with 30 arc sec parallelism UVIR blocking: UV and IR light between 400-1100nm is blocked at OD3 (0.1%) Visible light blocking: Visible light between 400-700nm at OD4 (0.01%) Scope of Delivery: Filter Specifications: Cell: Aluminium Type: Interference filter Filter thread / size: 1.25"

Item condition: new and original packed

Explore Scientific 1,25" O-III Filter

Item condition: new, but not original packed

Astronomik 2" UHC filter

Item condition: new and original packed

Astronomik 2" O-III filter 12nm

Item condition: new and original packed

Astronomik OIII-CCD-Filter, 12 nm, Anschluss 1,25"

Item condition: new, but not original packed

Astronomik CLS Filter 1,25"

Item condition: new and original packed

Astronomik H-Beta Filter 2'' The Astronomik H-Beta filter is made for the visual observing with 8" telescopes and larger. Only light of the very small H-Beta spectrum in which the hydrogen nebulas shines can pass. The contrast of this objects increases, so objects normally only visible on photos will be viewable for the naked eye. Which objects can be observed: This filter enables a very contrasty observing of hydrogen nebulas. Which telescopes can be used with this filter: We recommend the H-Beta filter for telescopes from 20 cm aperture onwards. Delivery contains: Filter Filterbox

Item condition: new and original packed

B+W Schneider Kreuznach Top-Polfilter 2"

Item condition: new and original packed

APM Greyfilter ND 3.0 1,25"

Item condition: new and original packed

Mars Observing Kit #80A to observe Martian polar caps and high clouds #25 to view detail in maria and polar ice caps #56 filter for viewing dust storms and polar caps 2x Barlow lens Hard Carrying Case

Item condition: new, but not original packed

Skywatcher 1,25" variable Polarizing filter

Item condition: new and original packed

Product description: Omegon premium Moon filter - to ensure that your lunar observing is fun Does the Moon appear far too bright when observing it through your telescope? The Omegon Moon filter reduces the brightness and increases contrast. It screws easy into your eyepiece, permitting relaxed observing and stopping the Moon from dazzling you. The advantages in a nutshell: Omegon neutral density filter - tones down moonlight for more comfortable observing neutral image - the Moon retains its natural appearance high contrast - discover thousands of craters and fine structures for your eyepiece - fits onto any 2" eyepiece with a filter thread The Moon is too bright - tone it down a bit The Moon can be so bright that you can easily read a newspaper by its light at night. But anyone looking through a telescope will note just how bright the Moon really is. It often irritates the retina and dazzles the eye in unpleasantly. No wonder - the full Moon is 25,000 times brighter than the brightest star in the night sky. So having a neutral density filter is definitely an 'ace up your sleeve' when observing the brighter lunar phases. Filter with 25% light transmission This filter is ideal for smaller and medium-sized telescopes up to a diameter of 150mm. The 25% light transmission reduces the brightness of the moonlight, allowing you to observe the Moon at any time - in comfort and without glare. Polished glass for a clear view You are purchasing a first class product with the Omegon Moon filter - a polished glass filter held in an anodised aluminium mount. The filter glass has been ground and stained throughout the entire glass volume. This avoidance of using a superficial coating means that it cannot wear out, even after many years of use. A Moon filter belongs in the eyepiece case of every amateur astronomer. But, above all, it is a must for comfortable lunar observing.

Item condition: new and original packed