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.

Optolong UV/IR Cut filter is designed for ultraviolet and infrared wavelength blocking to improve sharpness of the image as most of the optics are designed for the visible spectrum, because it’s very difficult to create a lens with the same focal point for the visible and IR spectrum.

It is used on a digital camera and the video, which do not have an IR protection filter toward an image sensor or were remodeled. This is important because unfiltered CCD and CMOS sensors are extremely susceptible to UV and IR rays just outside the visible spectrum that can have a very negative impact on image quality.

Main Use and Performance

Suitable for color CMOS and CCD cameras and modified DSLRs.

Use with monochrome CCD for astrophotography.

Available to assist in focusing.

Act as an outstanding dust shield, which prevents the possibility of dust settling on the lens during long time exposure.

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.

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).

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

它是一种 3nm 双波段，旨在大幅减少光污染的影响，3nm 将星云的辐射隔离为 H-Alpha（红色）和 OIII（绿-蓝）。它可以阻挡光污染，最大化​​星云信号，并使天空背景变暗。它还可以阻挡汞蒸气灯、高压和低压钠蒸气灯的人造光以及由我们大气中的中性氧排放引起的不必要的自然光。最大化星云在 OIII（496nm 和 500nm）和 H-alpha（656nm）中的主要发射线的传输。但是，与 DSLR、彩色/MONO CMOS 和 CCD 一起使用时，此滤镜不适用于快速比率系统。

L-Ultimate的优点在于只通过发射线OIII(500.7nm)和Ha(656.3nm)，这样其他光污染发射线全部被排除，成像时只捕捉到星云的发射和反射信号，因此图像的天空背景更暗，最大程度提升了星云的对比度和信噪比。在重光污染区域，该产品还能选择性地过滤通过星云发射线的光污染和杂波信号，最终避免光污染对天文摄影的影响。

与双窄带 L-eNhance 和 L-eXtreme 系列不同的是，L-Ultimate 是一款双 3nm 带宽滤镜，只通过 Ha 和 OIII 发射线。您将获得更暗的天空背景，图像对比度更高，对星星的抑制也更强。L-Ultimate 在光晕性能方面也进行了优化，因此在对亮星物体进行拍摄时不会出现明显的光晕。

特征

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