ZWO ASI174MM-MINI 2.1 MP CMOS Monochrome Astronomy Camera with USB 2.0 Autoguider Review (2026)

Who this camera is for

The ASI174MM-MINI is built for astrophotographers who want a dedicated autoguiding camera, typically paired with a mini guide scope or used off axis with a guider, to keep a main imaging telescope precisely tracking a target during long exposures. Its monochrome sensor and larger chip than ZWO's smallest guide cameras make it a strong choice for observers whose mount or guide scope combination has struggled to find enough usable guide stars with a smaller sensor camera, since a bigger sensor covers more sky and increases the odds of a bright star landing in frame. It also works for basic planetary imaging given its sensitivity, though that is a secondary use case.

Sensor and imaging specifications

At the core of the camera is a Sony IMX174 monochrome sensor measuring about 11.3 by 7.1 millimeters, delivering 1936 by 1216 pixels at 2.1 megapixels with a pixel size of 5.86 by 5.86 micrometers, a physically larger sensor and pixel size than entry level guide cameras built around smaller 1.2 megapixel sensors. The camera uses a 12-bit analog to digital converter and reaches a peak quantum efficiency of about 77 percent, meaning it captures a high proportion of the light that reaches the sensor, which translates into detecting fainter guide stars than a less sensitive sensor would pick up under the same conditions.

Speed, interface and physical size

The camera connects over USB 2.0 rather than USB 3.0, with an exposure range spanning from 32 microseconds up to 300 seconds and a frame rate of about 18.4 frames per second at full resolution, which is more than adequate for the relatively low frame rate demands of autoguiding software but a real ceiling for anyone hoping to also use it for high frame rate planetary lucky imaging. Despite its larger sensor, the mini housing keeps the camera compact and light, weighing about 140 grams, so it fits small guide scopes and off axis guider ports without adding significant weight or bulk to the imaging train.

Guiding performance in practice

Because autoguiding relies on repeatedly and quickly measuring a guide star's position to send tiny correction signals to the mount, a sensor with low read noise and high dynamic range, both cited for this sensor, helps the guiding software lock onto and track a star accurately even under less than perfect sky conditions or with a fainter guide star than a noisier sensor could use reliably. The larger sensor area compared with ZWO's smallest 1.2 megapixel mini guide cameras also means less need for precisely centering the guide scope, since a wider field increases the chance a bright enough star falls within frame on the first try.

Verdict and how it compares

This camera earns a strong score as a sensitive, larger sensor autoguiding camera, and it ranks just behind ZWO's own smaller and less expensive ASI120MM-Mini in the autoguider comparison it belongs to, reflecting that many observers find the smaller, cheaper camera sufficient for straightforward guiding while this model earns its higher price through better star detection in more difficult guiding situations. Buyers whose guide scope or off axis guider setup has struggled to find enough guide stars, or who want headroom for occasional planetary imaging, will get clear value from the larger sensor, while anyone guiding a simple, well matched setup may find a smaller, cheaper guide camera performs just as well.

Frequently asked questions