Condition:

This is a set of used Astronomik RGB filters + the L-3 UV/IR cut filter. They are 2" and in excellent, clean, dust-free condition. There are no marks or scratches and they come in their original jewel cases.

(Any dust you see in the photos is easily removable - it seems that these filters develop an electrostatic charge such that the dust in the air is just attracted to the filter.)  

Description:

Astronomik Deep-Sky RGB filter set

Astronomik has added a new range of RGB filters to its line of World class products. The new Deep-Sky RGB filters are designed for maximum deep sky imaging performance with CCD cameras.
Using Astronomik Deep-Sky RGB filters will benefit your imaging and will provide you with the highest-quality data for amazing images with unsurpassed sharpness, contrast and vivid colors.

We recommend the use of the Deep-Sky RGB filters for all modern CMOS or CCD cameras from ZWO/ASI, QHY, QSI, SBIG, ATIK, ALTAIR!
If you want to take the most beautiful pictures with your equipment, the Deep-Sky RGB filters are exactly the right choice!

Astronomik Deep-Sky RGB Key features:

• Maximum transmission of up to 95%
• Ultra-Sharp, pinpoint star images
• High contrast
• Easy to process data for vivid colours in the final image
• Optimized spectral windows for max photon counts on the sensor
• Made on finest, opticaly polished glass
• Extremly durable, scratch resistant coating
• MFR Coating technique for a wide range of focal ratios

Astronomik UV/IR Cut filter, L-3, 2"

Astronomik offers a range of three different ultraviolet (UV) and infrared (IR) blocking filters for the Luminance channel. These filters are designed to help you tune your setup to produce the sharpest, most contrast-rich images possible. The luminance channel is critical to a great final image because it provides the most signal, which means the filter should have the highest transmission possible with a wide spectral bandpass across the entire visible spectrum. This combination ensures the highest sensitivity and photon counts on your pixels.

However, not all optical instruments or additional optical elements like correctors, field-flatteners, or reducers have a perfect color correction. A Luminance filter with too wide a bandpass can show chromatic aberration of the optical system, resulting in soft or bloated stars and making image processing difficult. To address this, Astronomik offers its line of Luminance filters: the L-1 filter with the widest spectral window, the L-2 filter with a standard spectral window, and the L-3 filter with the narrowest spectral window.

Depending on the color errors of the instruments used, the Astronomik Luminance filter with the widest spectral window should be used.

• L-1 UV-IR Block filter: Ideal for optical systems free of chromatic aberration
• L-2 UV-IR Block filter: Suitable for most optical systems with a corrector or flattener
• L-3 UV-IR Block filter: Designed for refractors with less-than-perfect color correction to minimize bluish halos around stars

The transmission characteristics and coatings on the Astronomik Luminance filters are engineered to eliminate halos and reflections. Even with bright stars in the field of view, nebulae and galaxies are imaged with the finest structures and maximum contrast. 

Additional note for photographers under light-polluted skies

The Astronomik CLS CCD filter is recommended as a replacement for the Astronomik Luminance filter. The Astronomik CLS CCD filter provides approximately the same amount of light in all three color channels while blocking nearly all unwanted light pollution, resulting in much deeper images with much less background noise from light-polluted observing sites.

Technical data

• Glass thickness: 1mm (except Astronomik OWB Type 3 and XT filters)
• Finely polished optical glass, free of any striae, residual stresses, and bubbles
• Extremely scratch-resistant and durable coating
• Completely resistant against high humidity and aging effects
• Astronomik MFR coating (Astronomik Deep-Sky RGB, UV-IR Block L-1, L-2, L-3, and Narrowband-Emissionline filters)
• Parfocal with other Astronomik filters
• Diffraction-limited
• Optimized spectral windows
• Delivered in a high-quality, long-lasting filter box

Due to the high-precision machining of the carrier substrate, all Astronomik filters are parfocal with wedge errors far below all common tolerances. Astronomik filters are diffraction-limited, ensuring that the optical performance (resolution and contrast) of your telescope is not compromised. Issues concerning focal distances and the exact alignment of images from each color channel are therefore effectively eliminated. 

All Astronomik filters are ideal for modern cameras, including both CMOS- and CCD-based models, ensuring you capture the best possible images with your equipment. Sharpness, contrast, and the absence of any reflections and halos are guaranteed. Even with bright stars in the field of view, nebulae and galaxies will be captured with the finest structures. The Astronomik MFR coating is designed for optimal performance across a wide range of focal ratios of the optics used.

Every Astronomik filter undergoes a rigorous quality control process before delivery. Additionally, each Astronomik Narrowband-Emissionline filter is measured using a high-end PerkinElmer Spectrophotometer to ensure it meets the specifications published on our website. On the back of each Narrowband-Emissionline filter box, you will find a label detailing the precise spectral data for that specific filter, including the maximum transmission and the recommended range of focal ratios.