The Galaxy 400mm f/6.3 was the longest reach in Dixons' Prinz-branded preset telephoto lineup, sold from the 1970s as a budget option for extra reach without a first-party super-telephoto price. The same optical design was distributed by other importers under names including Spiratone and Photax.
The lens has a preset aperture ring running from f/6.3 to a small minimum, a 72mm filter thread, and a built-in tripod mount for its length and weight. It was sold both as a fixed M42 screw fitting and as a separable T2 base with interchangeable adapters, including Pentax K, suiting tripod-based shooting.
Reviews describe respectably sharp results with low chromatic aberration for a preset design, though the lens is heavy and unwieldy handheld, and the preset control is awkward for fast-moving subjects. It shares its optical formula with several other rebadged 400mm f/6.3 lenses from the same source.
These lenses appear regularly secondhand for £15 to £50 depending on mount and condition. Check for haze inside the long barrel, confirm the built-in tripod collar rotates freely, and test that the preset ring holds its aperture rather than drifting, a common fault on worn examples.