William Optics Mini Cat 51 mm

Description

William Optics Mini Cat 51 Ultra Portable Astrograph

The William Optics Mini Cat 51 Astrograph is built for astrophotography's who want wide-field images without the bulk of a traditional telescope. Compact, fast, and optically refined, it’s designed to capture large areas of the night sky—think nebulae, star fields, and comets—with impressive efficiency.

Fast Optics for Shorter Imaging Sessions

One of the most important specs here is the f/3.5 focal ratio. In practical terms, this allows significantly more light to reach your camera sensor compared to slower systems (like f/5). That translates to:

• Shorter exposure times
• Faster data collection during limited clear skies
• Better performance when imaging faint deep-sky objects

If you’re shooting targets like emission nebulae or wide Milky Way regions, this speed is a major advantage.

Wide-Field Imaging with Strong Optical Control

The Mini Cat uses a 178mm focal length, making it ideal for wide-field astrophotography. You can comfortably frame large celestial objects without mosaics.

Its 6-element Petzval optical design includes:

• 2 Super ED elements for reducing chromatic aberration
• Lanthanum glass for improved contrast and color correction

The result is sharp stars and accurate color across most of the frame—especially when paired with APS-C sensors. Full-frame cameras are supported, though edge performance may require some correction during post-processing.

Precision Focusing Without Mechanical Compromise

A common issue in astrophotography setups is image tilt caused by traditional focusing mechanisms. The Mini Cat addresses this with a patented internal focusing system (WIFD).

Instead of moving a drawtube, the system adjusts internal lens elements, which provides:

• Better optical alignment
• Reduced risk of tilt or flex
• Smooth, repeatable focusing

It’s also compatible with motorized focusers like the ZWO EAF, making it suitable for automated imaging setups.

Built for Portability

As the name suggests, portability is a core strength. The Mini Cat 51 is lightweight and compact enough to:

• Travel easily with small mounts
• Fit into grab-and-go astrophotography kits
• Pair well with portable tracking mounts

Despite its size, it doesn’t compromise on optical performance, making it a practical option for both backyard setups and dark-sky trips.

Real-World Use

This astrograph excels in:

• Wide-field nebula imaging
• Milky Way photography
• Comet tracking
• Large star clusters

It’s less suited for high-magnification planetary imaging, where longer focal lengths are required.

Who is this product for?

The Mini Cat 51 is ideal for:

• Astrophotography's focused on wide-field imaging
• Traveling astronomers needing lightweight gear
• Intermediate users upgrading from camera lenses
• Advanced users looking for a fast, portable secondary setup

If your goal is capturing expansive sky scenes quickly and efficiently, this telescope is purpose-built for that role.

What’s in the box

• William Optics Mini Cat 51 optical tube
• Mounting hardware (dovetail/base)
• Integrated handle
• Soft carrying case
• Documentation

Note: Guide scope and additional accessories (such as the 32mm Unguided) are sold separately.

Final Thoughts

The Mini Cat 51 stands out by combining very fast optics (f/3.5) with a compact, travel-friendly design and a mechanically robust focusing system. It’s not trying to be an all-purpose telescope—instead, it focuses on doing one job extremely well: capturing wide, detailed images of the night sky with minimal effort and time.

Optical Specifications

Focusing & Imaging

Camera Compatibility

Build & Mounting