Using the F/15 Maksutov as an astrograph

The F/15, 2700mm focal length 18cm aperture Maksutov is never intended to capture deep-sky images. Instead it excell’s at planets and the Moon.

However, with this focal length, it makes sense to give it a try at small objects like galaxies.

This is what came out of it, as a test, stacking 40 subs of 300s at gain 0. That’s 3 hours and 20 minutes. The detail is ok, what I noticed are triangular stars so I need to take a look at the collimation, seems to tight.

M66, Maksutov 180mm F/15 43x300s ASI2600MC

Compared to what my C11 did with an ASI183mm RGB last year:

M66, C11 F10 46x120s at G111 ASI183mm RGB

To dither or not to dither?

I have two similar sessions on the galaxy NGC3628, the ‘dimmer’ member of the Leo Triplet. One session was done without dithering, the second session with dithering. So maybe it’s educational to really compare the two results and verify what the effect is of dithering?

NGC3628 36x300S 800ISO Nikon D750 Esprit 120mm F7 NON DITHERED
NGC3628 54x300S 800ISO Nikon D750 Esprit 120mm F7 Dithered

The difference in background noise should be clear.

To be complete: the dithered image was 54x300s or 4hrs 30m exposure, while the non-dithered image was only 36x300s or 3 hours of exposure. Both nights were equal in quality.