Baader 2 inch Mark III MPCC Multi Purpose Coma Corrector Photographic Version MPCC 2458400 Review (2026)

What a coma corrector fixes

Fast Newtonian reflectors, especially those at f/6 or faster, produce a well known optical flaw called coma, where stars near the edge of the field appear stretched into small comet-like shapes rather than sharp points, an effect that becomes much more visible on a camera sensor than it typically is at the eyepiece. The MPCC Mark III corrects that distortion across the field without altering the telescope's native focal length, so the same focal ratio and image scale calculations still apply once the corrector is installed. Baader's independent lab testing, cited by resellers, found the MPCC delivers stars as small as about 12 microns across a full 35mm sensor, a meaningful claim for anyone shooting with a full frame astro camera on a Newtonian.

Focal ratio range and mounting

This Mark III version is optimized for Newtonians in the f/3.5 to f/6 range, an improvement over the original MPCC design, which was rated only down to f/4, so it now covers a wider range of fast imaging Newtonians without vignetting even at f/3.5. The corrector mounts in any standard 2 inch focuser and offers a 44 millimeter clear aperture through its M48 filter thread, accepting both T-2 threaded photographic adapters at M42x0.75 and 2 inch M48x0.75 threaded adapters depending on the camera setup being used. Baader also includes a removable 2 inch stopping collar, which can be taken off to increase back focus slightly when a particular camera train needs the extra spacing.

Getting the back focus distance right

Because a coma corrector's performance depends on the sensor sitting at a specific distance behind the lens assembly, Baader specifies a back focus of 55 millimeters when using the T-2 M42 thread and 57.7 millimeters with the M48 adapter, and getting that spacing wrong is one of the more common mistakes that leads to disappointing results with any coma corrector, not just this one. An optional adapter is available for direct coupling to a Baader Canon EOS protective T-ring, simplifying the spacing calculation for DSLR imagers using that specific camera mount. Imagers switching between cameras or adding filter wheels and other train components need to recheck the total spacing each time something changes in the optical train.

Photographic version versus visual use

As the name on this listing states, this is the photographic version of the MPCC Mark III, a designation Baader also sells alongside a photo-visual variant intended to perform well for both eyepiece and camera use. Buyers who intend to split time between visual observing and imaging with the same Newtonian should confirm which version fits their needs before ordering, since choosing the imaging-optimized variant for a visual-heavy setup may leave some performance on the table at the eyepiece compared with the dual purpose version. For a telescope used primarily or exclusively for astrophotography, the photographic version is the more straightforward choice.

How it compares to other coma correctors on the site

In the site's Best Coma Correctors guide, this photographic MPCC ranks second of seven, just behind Baader's own photo-visual MPCC V-1 Mark III set, which adds visual-use flexibility to essentially the same optical corrector. Other options in the guide include Explore Scientific's variable coma corrector, Baader's own Rowe Coma Corrector for a narrower focal ratio range, and 2 inch correctors from GSO and Sky-Watcher aimed at similar fast Newtonian astrographs. Buyers who want the option to also observe visually through the same corrector may prefer the photo-visual set ranked just above this one, while dedicated imagers can save a little by choosing this photographic-only version instead.

Frequently asked questions