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June 24th: Store is closed for Quebec National Holiday. Orders placed that day will ship on June 25th.
ZWO Atmospheric Dispersion Corrector

ZWO Atmospheric Dispersion Corrector

by ZWO
SKU ZWO-ADC
$128.00 - $128.00
$128.00
$128.00 - $128.00
$128.00
Price Match Policy!
  • Corrects atmospheric dispersion for sharper planetary images
  • Uses two H-K9L prisms with 2° deviation angles
  • Features 1/10 wave optical accuracy to preserve resolution
  • 1.25” barrels with non-marring brass compression rings
  • Independent levers and a rotatable scale for precise adjustment
3 in stock
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ZWO ADC Atmospheric Dispersion Corrector

    The ZWO ADC Atmospheric Dispersion Corrector neutralizes the color fringing caused by Earth's atmosphere, sharpening planetary and lunar views. It uses two counter-rotating H-K9L prisms, each with a 2° deviation angle and polished to a 1/10 wave accuracy, to recombine the dispersed spectrum of light back into a single, focused point. This correction is critical for high-resolution imaging, especially when planets are at low altitudes where dispersion is most severe.

    1/10 Wave Correction for High-Resolution Imaging

    Atmospheric dispersion acts like a weak prism, smearing a planet's light into a vertical rainbow that blurs fine detail. The ZWO ADC introduces an equal and opposite dispersion, effectively canceling the atmospheric effect. With optical surfaces polished to a 1/10 wave accuracy, the ADC corrects this color separation without introducing its own aberrations, preserving the native resolution of your telescope and letting you resolve finer cloud bands on Jupiter or subtler crater details on the Moon.

    Precise Adjustment with a Rotatable 360° Scale

    Properly using an ADC requires aligning its null point with the horizon and then adjusting the prisms to match the level of dispersion. The ZWO ADC simplifies this process with an intuitive control system. The rotatable scale and white locking screw let you easily set the horizontal "zero" position without rotating the entire ADC in your focuser. From there, two independent levers allow you to dial in the precise amount of correction needed, which you can see in real-time on your camera's live view.

    • Synchronized Levers: Overlapping slots allow the two prism levers to be moved together, simplifying the initial adjustment process.
    • Rotatable Scale: Lets you orient the measurement scale to the horizon, making it easy to set the levers symmetrically for optimal correction.
    • Secure Connections: Both the 1.25" nosepiece and eyepiece holder use brass compression rings, ensuring a firm grip on your camera and accessories without scratching their barrels.

    When to Use the ZWO ADC

    An ADC is not always necessary, but it is an essential tool for dedicated planetary imagers. Its effect is most dramatic when a target is below 60 degrees of altitude. For observers in the northern hemisphere imaging Jupiter or Saturn during their low-altitude apparitions, an ADC is the difference between a soft, color-fringed image and a sharp, detailed one.

    The primary trade-off is a minor reduction in light throughput from the extra glass. For bright targets like the planets and the Moon, this is insignificant compared to the massive gain in sharpness. However, for faint deep-sky objects where every photon counts and dispersion is less noticeable, an ADC is typically removed from the imaging train.

  • How does the ZWO ADC improve planetary images?

    When light from a planet passes through Earth's atmosphere, it gets dispersed into a spectrum, causing a blue fringe on top and a red fringe on the bottom. This blurs the image. The ZWO ADC uses a pair of prisms to create an opposite dispersion effect, recombining the colors into a single sharp point and restoring fine detail.

    Is the ZWO ADC necessary when planets are high in the sky?

    When a celestial object is directly overhead (near the zenith), atmospheric dispersion is minimal, and an ADC provides little to no benefit. Its function becomes critical when objects are below about 60° altitude. The lower the object, the more atmosphere its light travels through, and the more valuable the ADC becomes.

    How do I set up the ZWO ADC for imaging Jupiter from my backyard?

    First, insert the ADC into your focuser and attach your camera. Point at Jupiter and achieve focus. Rotate the entire ADC until the adjustment levers are perfectly horizontal. Lock the rotatable scale so the "0" mark aligns with the levers. Then, slowly and symmetrically move the levers apart, watching your live view screen. You will see the red and blue color fringes merge and the image become noticeably sharper. Fine-tune for the best possible view.

    Can I use the ZWO ADC for visual observing with an eyepiece?

    Yes. While most commonly used for imaging, the ZWO ADC works perfectly for visual observation. Simply place it between the diagonal and your eyepiece. The improvement in sharpness and the reduction of color fringing on planets and the lunar limb will be immediately apparent, especially at high magnification.

    Is the ZWO ADC useful for deep-sky objects like galaxies or nebulae?

    Generally, no. Atmospheric dispersion primarily affects very bright, sharp point-sources of light like stars and planets. Faint, diffuse deep-sky objects are not resolved with enough detail for dispersion to be a significant problem. The slight light loss from the ADC's prisms would be more detrimental than any minor sharpening benefit.

    What is the purpose of the 2° prism deviation angle on the ZWO ADC?

    The 2° deviation angle determines the maximum amount of corrective power the ADC can apply. This value was chosen to be effective for correcting dispersion for planets even down to very low altitudes (e.g., 20-30 degrees) without being so aggressive that it becomes difficult to make fine adjustments for objects higher in the sky.

  • SKU ZWO-ADC
    Prism Material H-K9L (BK-7 Equivalent)
    Prism Angle 2°
    Optical Surface Accuracy 1/10λ
    Connections 1.25" Barrel (Nosepiece & Holder)
    Clamping Mechanism Brass Compression Rings

    • ZWO Atmospheric Dispersion Corrector

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  • ZWO 2-Year Limited Warranty