This is my first light processed image with the new QHY268M. It is M51 and vicinity in LRGB with the Teleskop Services Photoline 130/910 Apochromatic Refractor. Overall it was a successful run of nights with the new camera. I have one more LRGB and another L-only image in process from this first series.

My previous CMOS experience was with the QHY183M, which is a good camera (especially for the price), but it suffers from amp glow, small sensor size, limited bit-range and limited full well capacity and dynamic range. The 268M is superior, or course, being 16-bit with no amp glow and an impressive full well capacity and dynamic range. For those interested in my measured characteristics of this camera for different gain settings, please refer to this link. With the new camera I also purchased the QHYOAG-M and QHYCFW3-M-US version. And I am in the process of fitting in a new set of 36mm Astrodon filters, with only the LRGB and OIII in my possession at this time. For those interested in the configuration and spacing, I posted a picture and description at this link.

The original version is a wider FOV image of M51 and vicinity. As of this writing, I do not have the adapter needed to connect the new imaging gear to the TSFLAT 2,5 flattener. One can see that this is going to be required to minimize the slant of stars along the edge of the field of view; it's quite prominent. The adapter is now in shipping and I ought to have it installed the next time I image.

I've image M51 many times before and in fact have targeted it on a couple of more sessions this season to observe the results with other camera and scope combinations. At some future time I may compile a comparison of these images into a single mosaic, but at this time my interest is in introducing this camera into my efforts.

M51 is one of the most famous Messier objects, and many, including I, have reported on it in great detail in the past. Here is a link to an image I made two years ago with a much different combination of gear.

I hope to be able to use this camera again soon. One thing I only realized after the fact was by how much I exceeded the "optimum" exposure length. One conventional rule of thumb is that the upper limit should be an exposure time at which the calibrated skyfog (that's the position of the histogram from sky background minus offset from bias) is about 10 RN^2, where RN is the read noise in units of [e-]. This camera has read noise of 3.5 [e-] for its gain parameter of 0. This is a gain of about 0.79 [e-/ADU] from my measurements. This implies I should have set the exposure to place the calibrated background level at around 123 [e-] or so. I exceeded that by several factors, and consequently I blew more stars out than necessary. This will be my main focus of attention next time I image!

Thank you for your attention, and I look forward to posting the other images from this first light series in the near future, and hopefully I'll have clear nights soon for more and improved imaging with the new camera.