The Astronomik CLS is a budget filter for visual observation, Black & White photography and CCD photographs of nebulae, galaxies and star clusters with astronomical instruments of any size. 

The Astronomik CLS blocks the light of the spectral lines of mercury and sodium-vapor lamps and lets the largest part of the visible light and H-alpha emissions pass. All the important emission lines, as well as the spectral region that the very well dark adapted eye can see, can pass through the filter.

Main use

The filters are optimized for use with aperture ratios from 1:3 to 1:15. Transmission losses and chromatic distortions, which are problems with other filters, only appear with Astronomik filters when extremely bright aperture ratios of 1:2 and more are used. The CLS filter is suitable for use with telescopes of all aperture sizes.

Suitability

• Visual observation (dark skies): Good, to reduce light pollution by mercury-vapour lamps (streetlight)
• Visual observation (urban skies): Good, an UHC-E or UHC filter is more suitable
• Film photography: Very good, colour balance is near perfect
• CCD photography: Good, when used with an additional IR-block-filter
• DSLR photography (original): Good, colour balance shifted but contrast enhanced
• DSLR photography (astro modified): Very good, colour balance is near perfect
• DSLR photography (MC modified): Good, when used with an additional IR-block-filter
• Webcam / Video (Planets): Unsuitable
• Webcam / Video (Deep Sky): Very good, if light pollution is a big problem

Technical Data

• 92% transmission at 486nm (H-beta)
• 92% transmission at 496nm (OIII)
• 92% transmission at 501nm (OIII)
• 97% transmission at 656nm (H alpha)
• pass from 450 to 540nm and beyond 650nm
• Parfocal with other Astronomik filters
• Glass thickness: 1mm
• Completely resistant against high humidity, scratches and aging effects
• Diffraction limited, the filter will not reduce the optical performance of your telescope!
• Astronomik filters are delivered in a high-quality, long lasting, filter box
• Since 2008 we do ship filters with a completely new design. Any kind of halo or strange reflection is a matter of past

From the start, the Astronomik OIII filter has been very specifically designed for the visual observation of gaseous and planetary nebulae. The extremely narrow pass band of the two OIII lines brings a substantial contrast gain to these lines even under best observation conditions. On faint super nova remnants and faint planetary nebulae the Astronomik OIII filter will often make the difference as to whether the object can bee seen or not!

The optimal aperture ratio for the use of the filter is 1:3.7 to 1:15 with apertures of more than 6" (150mm). Transmission losses and chromatic distortions, which arise with other filters, occur with Astronomik OIII filters only when extremely bright aperture ratios of 1:3 and more come into play. The Astronomik OIII filters thus can expand the view of dispersed objects, generally speaking, to the whole visual field of view of the eyepiece and are not limited to only the center of the eyepiece.

Main use

Since enough light must be available to make use of the OIII filter it is best to use this filter with apertures of more than 6" (150mm). Smaller instruments do not gather enough light for meaningful and satisfying astronomical work. However, please note: Many experienced Deep Sky observers, with apertures of more than 10" (250mm), prefer using the OIII filter instead of the more versatile UHC filter. Due to the high optical quality of the Astronomik OIII filter substrate you will see the same needle-sharp stars as you would from your regular telescope.

The UHC-E Filter increases contrast of emission nebulae and comets and blocks the light of typical streetlights as well as airglow. It is best suited for telescopes up to 5" / 125mm.

Main use

The Astronomik UHC-E filter provides a FWHM of 45nm and blocks the light of typical streetlights (e.g. sodium and mercury vapour) as well as airglow. Thus it increases contrast between your target and the night sky. The contrast enhancement is less than that of the Astronomik UHC filter, but at the same time the transmitted amount of starlight is greater. It's therefore better suited to smaller telescopes. As the UHC-E filter passes a spectral line of Carbon (due to the higher FWHM) it opens up the possibility of comet observation.

Other uses

• Observation of Jupiter’s clouds.
• Easier resolution of Double Stars.
• Photography under light-polluted skies with DSLRs and other cameras.

Suitability

• Visual observation (dark skies): Reasonable, an UHC filter is more suitable
• Visual observation (urban skies): Good, for telescopes up to 125 mm aperture and medium exit pupil
• Film photography: Good, but very long exposure times
• CCD photography: Good, when used with an additional IR-block-filter
• DSLR photography (original): Good, colour balance is near perfect
• DSLR photography (astro modified): Good, colour balance is near perfect
• DSLR photography (MC modified): Good, when used with an additional IR-block-filter
• Webcam / Video (Planets): Unsuitable
• Webcam / Video (Deep Sky): Very good, if light pollution is a big problem

Technical Data

• typ. 94% transmission at 486nm (H-beta)
• typ. 95% transmission at 496nm (OIII)
• typ. 95% transmission at 501nm (OIII)
• typ. 94% transmission at 656nm (H alpha)
• transmission 465nm to 530nm and above 645nm 
• Full width at half maximum 45nm
• Parfocal with other Astronomik filters
• Glass thickness: 1mm
• Completely resistant against high humidity, scratches and aging effects
• Diffraction limited, the filter will not reduce the optical performance of your telescope!
• Astronomik filters are delivered in a high-quality, long lasting, filter box
• Since 2008 we do ship filters with a completely new design. Any kind of halo or strange reflection is a matter of past

The Astronomik UHC is THE filter for visual observing.

You will enjoy using your Astronomik UHC filter because you will see more stars and more details in deep-sky-objects compared to using filters from all other manufacturers.

The Astronomik UHC (Ultra High Contrast) filter allows the transmission of nearly 100% of the radiation from both O-III and the H beta lines. Though the second window for the H-alpha-line is not intended for visual observing, it is important, if the filter is used with an electronic device. All annoying, scattered light from other wavelength sources, including local artificial light pollution, is reliably filtered out. With this strong blocking of the sky background an unexpected wealth of detail becomes visible for gas nebulae and planetary nebulae.

Main use

Astronomik UHC filters’ astounding high light transmission brings better views of deep-sky-objects even to small telescopes! The high transmission of our optical glass filters means that enough light is available to allow successful visual observations with telescopes beginning at 2" (50mm) aperture. Our Astronomik filters are optimized for use with telescope focal length f / ratios of f/4 to f/15. Transmission losses and chromatic distortions, which arise with other filters, only occur with Astronomik filters when extremely bright aperture ratios of 1:2 and more come into play. Another major advantage of our Astronomik UHC filter is the high optical quality of the filter glass. When using Astronomik UHC filters you will quickly notice the same needle-sharp stars which you are familiar with from your astronomical instrument without any filter!

Suitability

• Visual observation (dark skies): Very good, for telescopes of all apertures and high exit pupil
• Visual observation (urban skies): Very good, for telescops from 100 mm aperture
• Film photography: Reasonable, but very long exposure time
• CCD photography: Good, when used with an additional IR-block-filter
• DSLR photography (original): Good, colour balance shifted but contrast enhanced
• DSLR photography (astro modified): Very good, colour balance is near perfect
• DSLR photography (MC modified): Good, when used with an additional IR-block-filter
• Webcam / Video (Planets): Unsuitable
• Webcam / Video (Deep Sky): Good, if light pollution is a big problem

Technical Data

• typ. 95% transmission at 486nm (H-beta)
• typ. 95% transmission at 496nm (OIII)
• typ. 95% transmission at 501nm (OIII)
• typ. 95% transmission at 656nm (H alpha)
• optimum position of transmission for telescopes with focal ratios from f/10 to f/3,5
• Entire Blocking of annoying wavelengths
• Ideal All-round Deep Sky filter even for small telescopes
• Not sensitive to humidity or aging
• Scratch-resistant!
• Excellent carrier material. The optical performance of your telescope is not reduced by the filter in any way.
• Parfocal with other Astronomik filters
• Glass thickness: 1mm
• Completely resistant against high humidity, scratches and aging effects
• Diffraction limited, the filter will not reduce the optical performance of your telescope!
• Astronomik filters are delivered in a high-quality, long lasting, filter box

The UHC (Ultra High Contrast) broadband filter is designed to improve the visibility of various deepsky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lightings including mercury vapor lamps, both high & low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). Together with the highly transparent in main nebula emission lines at OIII(496nm and 500nm), H-beta (486nm), NII(654nm and 658nm), H-alpha(656nm) as well as SII(672nm), the filter is suitable for enhancing the contrast and details for both visual and photograghic purpose at sub-rural area with heavy light pollution.

Main Use and Performance

Suitable for color CCD cameras and unmodified DSLRs.

UHC with narrower passband provides higher contrast than CLS. Thus it is more suitable for urban environment where you suffer from severe light pollution.

UHC has a substantial red passband and offer superb views for objects like the Orion Nebula (M42).

Light pollution filter do not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.

WARNING: The filters of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.

Optolong LRGB filter set is designed for maximum contrast and with extremely high gradients for clear differentiation of colors. The LRGB filter set divides the spectrum into its components red, green, blue and luminance.

OIII emission overlaps on blue and green filters with maximum transmission to allow high efficiency and natural color imaging. Gap between green and red filters serves to block out the primary Sodium light pollution line at 589nm and improves color balance and separation.

• RGB, parfocal:1:1:1
• Creat images in their true original colors showing a wealth of natural detail;
• Steep bandpass filters to eliminate UV and IR interference;
• Include Luminance (UV/IR Cut), Red, Green, and Blue filters to reproduce the star's color
  
  

Adjust the brightness level of the Moon, Venus, and other bright objects with the Optolong Variable Polarizer. A standard Moon Filter is similar to a pair of sunglasses. They work fine, but sometimes the scene is too dark or too bright, and there’s not a lot you can do about it. A variable polarizing filter is much more flexible than a Moon filter. It allows you to set the percentage of attenuation by turning the top section of the two-piece filter. Simply attach the 2" threaded filter to a like-sized eyepiece or Astro accessory barrel, and then slowly rotate the top half of the filter—it turns 360°—to achieve the results you desire.

The Optolong Variable Polarizing Filter also works great to cut brightness when you are using your telescope for terrestrial observations or photography. If you have ever done photography through a SLR or DSLR camera, you may have already been introduced to the qualities of a polarizing filter, since it is a very popular accessory for polarizing the light and making the sky appear bluer. You will especially appreciate a polarizing filter when viewing over water or photographing a scene that includes a river or body of water. Simply turn the filter until you achieve the most glare-free results—you will really see the difference.

L-eXtreme is a two 7nm bandpass filter which can be used with one-shot color cameras like DSLR's (digital SLR), and monochrome CCD cameras, it is also more suited for fast systems. The convenience and cost effectiveness of this filter allows amateurs to image a rich emission nebulas, even in bright, light pollution skies. Optolong believes the design of L-eXtreme filter would be better choice for fast systems in competitive price. It isolates the H-Alpha, and Oxygen III nebula emission lines so that the contrast and signal-to-noise ratio between nebulae were maximized. For people who is living in very light polluted areas, or when the moon is out, the L-eXtreme will be a good filter.

Unlike the Optolong L-eNhance filter which is a tri-band (transmits Hb, Ha, and OIII), the L-eXtreme filter is dual band that passes Ha and OIII emission lines.The advantage of the L-eXtreme filter is that there is no transmission between the H-beta and OIII lines, as there is no nebula emission lines there. In this case, it isn't letting light pollution come through so that maximize nebulas signal and make the sky background darker while imaging. The L-eXtreme filter should better isolate the emission lines only and better protect from light pollution.

Hydrogen is the largest, the most primitive, the simplest, and the oldest element in the universe. Scientists consider that Hydrogen amounts to more than 90% of visible substance in space. Our sun is 5 billion years old, but so far hydrogen is still the key matter of nuclear fusion. While the sulfur element does not have much scientific significance, so keeping H and O is meaning for exploration of life.
Therefore, we highlight H-a, H-b, O3 and O2, and reduce the signal of sulfur.

Spectrum and Characteristics

• Sbustrate: B270
• Thickness: 1.85mm
• Tpeak: T>90%
• Blocking range: 300-1000nm
• Blcoking depth: light pollution line blocking >99%
• Surface quality: 60/40
• Transmitted Wavefront RMS: λ/4

L-eNhance filter
The relentless spread of urbanization and its associated light pollution have become a growing problem for all amateur astrophotographers. The current solutions to the problem can be expensive and might include the purchase of a monochrome camera, several types of narrowband filters, and a filter wheel.

Optolong L-eNhance filter provides an economical and practical solution for amateurs. It is a dual-band pass filter that has been designed for DSLR (digital SLR), color CMOS, and monochrome CCD cameras. The convenience and cost-effectiveness of this filter allow amateurs to image a rich selection of astronomical images, even in bright, heavily light-polluted areas. Optolong believes the design of our L-eNhance filter is a technical innovation among filters. It effectively isolates the H-Alpha, H-Beta, and Oxygen III nebula emission lines and achieves a maximum transmission of up to 90%. The performance of this filter delivers images that superbly control the impact of light-polluted skies.

Hydrogen is the largest, the most primitive, the simplest, and the oldest element in the universe. Scientists consider that Hydrogen amounts to more than 90% of visible substances in space. Our sun is 5 billion years old, but so far hydrogen is still the key matter of nuclear fusion. While the sulfur element does not have much scientific significance, keeping H and O is meaningful for the exploration of life.
Therefore, we highlight H-a, H-b, O3, and O2, and reduce the signal of sulfur.

2. Spectrum and Characteristic
Substrate: B270
Thickness: 1.85mm
Tpeak: T>90%
Blocking range: 300-1000nm
Blocking depth: light pollution line blocking >99%
Surface quality: 60/40
Transmitted Wavefront RMS: λ/4
Parallelism: 30s

How to read the chart?

▲The horizontal axis is the Wavelength in Nanometers(nm).

▲The vertical axis is transmission in %.

▲The WHITE line shows the transmission of the filter. The artificial emission lines are shown in Yellow. The emission lines from the constellation are shown in GREEN, BLUE, AND RED.

SKU: 13801

Optolong L-Pro 1.25 inch is multi-bandpass filter which offers better color balance by maximizing the transmission band. The balanced transmission allows astrophotos to be taken with minimal color cast to broadband emission objects such as galaxies, reflection nebulae and globular star clusters.

Warning - Do not use this filter for solar purposes !

Optolong L-Pro (L-Professional) filter is designed to improve the visibility of various deepsky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lightings including mercury vapor lamps, both high & low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). Together with the highly transparent in main nebula emission lines at OIII(496nm and 500nm), H-beta (486nm), NII(654nm and 658nm), H-alpha(656nm) as well as SII(672nm), the filter is suitable for enhancing the contrast and details for both visual and photograghic purpose at sub-rural area with heavy light pollution.

Optolong L-Pro is multi-bandpass filter which offers better color balance by maximizing the transmission band. The balanced transmission allows astrophotos to be taken with minimal color cast to broadband emission objects such as galaxies, reflection nebulae and globular star clusters. L-Pro is the best choice for light pollution suppression.

• Optical glass fine material
• Spectrum: 380-750nm
• Surface Quality: 60/40 (Refer to MIL-O-13830)
• Fine-optically polished to ensure accurate 1/4 wavefront and < 30 seconds parallelism over the both surfaces
• High transmission at major nebula emission lines (i.e. H-alpha 656nm, OIII 496nm&500nm, SII 672nm and H-beta 486nm).
• Precision off-band blocking, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm).

The QSI 726 is the optimum camera for most amateur telescopes. The
28mm diagonal IMX571 maximises the sharpest parts of a telescope’s
image and is less affected by coma and vignetting than larger sensors.
As with its bigger brother the 760, cable clutter is reduced thanks to
the integrated filter wheel (36mm), 2 USB2 in sockets and power out.
Power sockets have threaded connections for maximum reliability.

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