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July 1st: Store will be closed for Canada Day. Orders placed that day will ship on July 2nd.
ZWO IR 850nm Pass Filter – 1.25"

ZWO IR 850nm Pass Filter – 1.25"

by ZWO
SKU ZWO-850IR1-25
CA$31.00 - CA$31.00
CA$31.00
CA$31.00 - CA$31.00
CA$31.00
Price Match Policy!
  • Passes Infrared Light > 850nm
  • Dramatically Steadies Planetary Views in Poor Seeing
  • Enables Daylight Planetary and Lunar Imaging
  • Standard 1.25" (31.75mm) Threaded Filter Cell
  • Includes Protective Plastic Case
1 in stock
Qualifies for FREE Shipping in Canada on orders over $500.
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ZWO 850nm IR Pass Filter - 1.25"

    The ZWO 850nm IR Pass Filter isolates a specific slice of the near-infrared spectrum, transmitting only wavelengths longer than 850nm. Housed in a standard 1.25" (31.75mm) threaded cell, this filter is a specialized tool for high-resolution planetary and lunar imaging, effectively bypassing the atmospheric turbulence that blurs details in the visible spectrum.

    Cut Through Bad Seeing at 850nm

    Atmospheric turbulence, or "seeing," is the primary obstacle to sharp planetary detail. Because longer wavelengths of light are less scattered by air currents, imaging at 850nm and beyond dramatically stabilizes the image. This allows you to resolve finer details in Jupiter's cloud bands, the Cassini Division in Saturn's rings, and subtle craterlets on the Moon, even when seeing conditions are poor or your target is low on the horizon.

    Daylight Planetary Imaging Beyond 850nm

    By aggressively blocking all visible light below 850nm, this filter renders the daytime sky nearly black to an IR-sensitive camera. This unique capability opens up the possibility of imaging bright planets like Venus and Jupiter during daylight hours. The result is a high-contrast image of the planet against a dark background, free from the glare of the blue sky.

    ZWO 850nm vs. 685nm IR Pass: Which to Choose?

    ZWO offers multiple IR Pass filters, and the choice depends on your conditions and camera. The 850nm filter is the more specialized of the two most common options.

    • ZWO 685nm IR Pass: This filter allows more light to reach the sensor, resulting in a brighter image and shorter exposure times. It is a great all-around choice for improving detail in average-to-poor seeing and works well with a broader range of monochrome cameras.
    • ZWO 850nm IR Pass: This filter is the ultimate seeing-killer. When conditions are exceptionally turbulent, the 850nm passband delivers the steadiest possible image. The trade-off is a significantly dimmer signal, which requires a camera with high IR sensitivity and potentially higher gain settings to achieve focus and capture data.

    Designed for Monochrome Imaging in a 1.25" Cell

    This filter is designed exclusively for astro-imaging with a monochrome camera; the human eye is not sensitive to 850nm light, so it cannot be used for visual observation. Its performance is directly tied to the quantum efficiency of your camera in the near-infrared. For best results, pair the ZWO 850nm IR Pass filter with a mono camera known for strong IR response. The industry-standard 1.25" (31.75mm) threaded cell fits any standard 1.25" filter wheel or nosepiece.

  • How does the ZWO 850nm filter improve imaging of Jupiter on a turbulent night?

    On nights with poor seeing, the Earth's atmosphere blurs the fine details of planets like Jupiter. The ZWO 850nm filter blocks the shorter, more easily scattered visible wavelengths and only lets the steadier, longer-wavelength infrared light through. This results in a much more stable image on your sensor, allowing you to capture sharper details in the Great Red Spot and equatorial cloud bands that would otherwise be a shimmering mess.

    Can I use the ZWO 850nm IR Pass filter with my color astronomy camera to image the Moon?

    While some color cameras have sensitivity into the infrared, they are not ideal for the ZWO 850nm filter. The Bayer matrix on a color sensor blocks a significant portion of the already-dim 850nm signal, leading to very long exposures and noisy results. For lunar or planetary imaging with this filter, a monochrome camera with high IR sensitivity is strongly recommended for the best detail and signal-to-noise ratio.

    Is the ZWO 850nm filter suitable for visual observation?

    No. The human eye cannot see light at a wavelength of 850nm. Looking through an eyepiece with this filter attached will result in a completely black field of view. It is a specialized tool designed exclusively for use with an infrared-sensitive astronomy camera.

    What is the main difference between the ZWO 850nm and a 685nm IR Pass filter?

    The primary difference is how aggressively they cut off visible light.

    • A 685nm filter is a good general-purpose choice, offering a significant improvement in seeing with a relatively bright signal.
    • The 850nm filter provides maximum seeing stabilization for the most turbulent conditions but passes much less light, requiring a very IR-sensitive camera and longer exposures or higher gain.

    Why would I want to image planets during the day with the ZWO 850nm filter?

    Imaging during the day allows you to capture planets when they are at their highest point in the sky, where atmospheric distortion is at a minimum. The ZWO 850nm filter makes this possible by blocking the visible light that makes the sky appear blue, effectively creating a dark background for your camera and allowing bright planets like Venus or Jupiter to be imaged in high contrast.

    Does the ZWO 850nm filter require a filter wheel?

    No, a filter wheel is not required. The filter's 1.25" cell is threaded to screw directly onto any standard 1.25" camera nosepiece or accessory. However, using it in a filter wheel makes it easy to switch between the 850nm filter and other filters (like LRGB) without disassembling your imaging train.

  • SKU ZWO-850IR1.25
    Filter Type IR Pass / Luminance
    Size 31.75mm (1.25")
    Format Threaded, Round
    Passband > 850nm

    • ZWO 850nm IR Pass Filter in 1.25" Cell

      × 1

    • Plastic Filter Case

      × 1

  • ZWO 2-Year Limited Warranty