My new Skywatcher Quattro 150P

Published on 3 September 2023 at 16:32

Early this year (2023) I thought about upgrading my gear for wide field images. I was thinking about a new APS-C or even full frame camera and at the same time moving from OSC to monochrome with a filter wheel. I was still hesitating, because even a kit of a cooled monochrome APS-C with filter wheel and filters (e.g. ZWO Kit ASI2600 MM Pro - 7 Pos 36 mm filter wheel L-RGB & Narrowband) is more than 4.000 EUR and the gain in field view is small:

Comparison of the field of view for three different sensors: 4/3 (left) vs. APS-C (center) vs. full frame (right) using Stellarium at the example of M31 with a focal length of 1000mm.

Then I read an article, if it is really worth investing in monochrome compared to OSC with multi band filters. I calculated the data volume and the processing time for a full frame sensor with monochrome filters, and came to the conclusion that I would have to invest in a new PC, new SSD drives and somehow get more imaging time (but I am not the weather god). So I abandoned the plan of going monochrome - but would it be worth investing in an OSC camera with larger sensor?

I checked solutions with smaller focal length instead and found the Skywatcher Quattro 150P with a focal length of 600 mm. It comes with a coma corrector which reduces the focal length by factor 0.86.

Comparison of the field of view for three different focal length with a 4/3 sensor: 1000 mm (left) vs. 600 mm (center) vs. 516 mm (right).

The gain in field of view with the Quattro is comparable to a full frame sensor at much lower cost. Furthermore, an f/4 or less halves my exposure time. I know that there are many more technical details to be considered in this discussion (pixel size, aperture, seeing) but I finally came to the conclusion that it is better to invest in a second telescope.

I purchased the new Quattro with a second ZWO EAF because I did not want to switch the EAF between the two scopes.

My new Quattro with a ZWO ASI 294MC Pro and guiding scope on a Skywatcher AZ-EQ 5.

I also invested in a new dual-band filter, an Optolong L-eXtreme as the fast focal ratio would allow sort imaging times even at very low bandwidth of the filter lines.

I had to wait some weeks for the first lights, as June was approaching and the weather was bad. But finally I was able to take images of the Pelican Nebula and the Veil Nebula with low imaging time (about 2 hours).