ZWO ASI294MC Colour Astronomy CMOS Camera

ZWO ASI294MC Colour Astronomy CMOS Camera

The ZWO ASI294MC is a one-shot colour CMOS astronomy camera built around the Sony IMX294CJK back-illuminated sensor. With a true sensor diameter of 23.2 mm - slightly larger than Sony's own specification of 21.63 mm, as confirmed by ZWO's own measurements - this camera offers a generous field of view that suits a wide range of telescope focal lengths. The 4.63 µm pixel size strikes an excellent balance between resolution and light-gathering ability, making the ASI294MC a genuine all-rounder for astrophotography.

As a one-shot colour camera, the ASI294MC captures full-colour images in a single exposure without the need to swap narrowband or broadband filters. For astrophotographers who want to spend their clear nights imaging rather than cycling through L-RGB filter sets, this approach offers a significant practical advantage - and the results speak for themselves.

Outstanding sensitivity for faint objects

The Sony IMX294CJK sensor uses BSI (Back Side Illumination) technology, which places the photosensitive layer directly facing incoming light without wiring structures blocking it. The result is a peak quantum efficiency exceeding 75%, which translates into noticeably shorter exposure times compared to conventional front-illuminated sensors and even many older CCD cameras. Faint nebulae and distant galaxies that would require long integrations with less sensitive cameras begin to appear within just a few seconds of exposure with the ASI294MC.

HCG mode - low noise at high gain

One of the most distinctive features of the ASI294MC is its HCG (High Conversion Gain) mode. When the gain is set above 120 (12 dB), the camera automatically switches into HCG mode, reducing read noise to below 2 electrons. This means you can push the gain aggressively - equivalent to raising ISO on a DSLR - to shorten individual sub-exposures to 30 seconds or less, without incurring a significant noise penalty. Short sub-exposures effectively eliminate the impact of atmospheric seeing and mount tracking errors on each individual frame, and a large number of short exposures can be stacked to match the signal quality of fewer long ones.

At the same time, the full well capacity of 63,700 electrons ensures that even relatively bright stars retain their structure without burning out, preserving a wide dynamic range across the entire image.

Planetary and lunar imaging

The high sensitivity of the ASI294MC makes it equally capable as a planetary camera. Very short exposures freeze atmospheric turbulence, allowing you to capture sharp frames for lucky imaging stacking. The 4.63 µm pixels resolve fine planetary detail even at moderate focal lengths, so a Barlow lens is not always necessary. Lunar imaging benefits from the large sensor area, which covers wide regions of the lunar surface in a single frame and supports detailed mosaic work.

AR protective window and IR sensitivity

The camera ships with an anti-reflection (AR) protective window that maintains full sensitivity across the visible spectrum and into the near-infrared. This makes the ASI294MC particularly attractive for hydrogen-alpha and infrared imaging without any additional modification. If infrared light needs to be blocked - for standard colour imaging of planets or the Moon - a separate IR-cut filter is required and can be threaded directly onto the camera using the included M42 adapter.

Software and drivers

ZWO provides free drivers and software for Windows, macOS and Linux, available directly from their website. The ASI294MC is fully compatible with SharpCap, FireCapture, Sequence Generator Pro, NINA, Astro Photography Tool and other popular astrophotography applications, as well as ASCOM and INDI for automated imaging workflows.

Technical specifications