Takahashi Mewlon 210 Vignetting on Full Frame

The Takahashi Mewlon 210 Dall-Kirkham Cassegrain only has an 18mm image circle at prime focus, and 39mm with the dedicated reducer.

Here are some images of daytime scenes taken with a Canon 6D full-frame DSLR.

Native focal length (2415mm, f/11.5)

With a Televue TRF2008 0.8X reducer/flattener for the TV85 (designed for 600mm radius of curvature) (f/9.2)

and with an Altair Astro 0.6X reducer/flattener (no longer available, but also sold by some other Europe-based sellers) (f/6.9)
 I will try to get some images of a large globular like Omega Centauri when I get the chance, but the illuminated field is not bad at all (an f/4 newtonian with a Paracorr has a comparable field to the Mewlon with the 0.6X reducer!)

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