Takahashi CCA-250 0.72x 645 Reducer-CA

Product Overview

The 645 Reducer-CA 0.72x is Takahashi's dedicated focal reducer for the CCA-250 Cassegrain astrograph, cutting its focal length by 0.72x to reach 890mm at f/3.6. The reducer delivers a Φ60mm image circle, sized for medium-format and large full-frame sensors.

Who It's For

This reducer suits CCA-250 owners who want a materially faster imaging system for deep-sky work with a larger-format camera. Increasing the speed of a Cassegrain design this way shortens integration time on faint targets without sacrificing the large-aperture light grasp the CCA-250 is built around.

Key Features & Design

• 0.72x reduction: speeds up the CCA-250's optical system to f/3.6 at 890mm.
• Φ60mm image circle: sized for larger imaging sensors, medium format included.
• Dedicated CCA-250 fit: engineered specifically for this telescope's Cassegrain optical path rather than adapted from a refractor reducer.

Optical / Mechanical Design

Back focus with the reducer installed is 56.2mm on the CCA-250. See the Takahashi Back Focus Guide for the full spacing chain when planning your camera train.

Recommended Uses

Fast deep-sky imaging on the CCA-250 with medium-format or large full-frame cameras; galaxy and nebula imaging where a faster focal ratio meaningfully shortens total exposure time on a large-aperture Cassegrain.

Compatibility and Accessory Notes

This reducer is specific to the CCA-250 — the related 645RD QE 0.72x reducer serves the FSQ-106EDX4 instead, and the two aren't interchangeable between telescopes despite the similar naming and reduction factor.

Frequently Asked Questions

Is it difficult to set up?

No — it installs into the CCA-250's optical path as a dedicated fit, and the 56.2mm back focus figure is fixed once it's in place.

What is it best used for?

Fast deep-sky astrophotography on the CCA-250 with medium-format or large full-frame sensors.

Does it work for visual observing?

No — it's built to deliver a flat photographic image circle rather than a visual eyepiece path.

What else do I need with it?

Your camera's own adapter to complete the connection at the 56.2mm back focus figure.

Bottom Line

A dedicated 0.72x reducer for the CCA-250 that reaches 890mm at f/3.6 across a Φ60mm image circle for medium-format astrophotography, at a 56.2mm back focus.