  Scientific complementary metal-oxide-semiconductor (CMOS) detectors have
developed quickly in recent years thanks to their low cost and high
availability. They also have some advantages over charge-coupled devices
(CCDs), such as high frame rate or typically lower readout noise. These sensors
started to be used in astronomy following the development of the first
back-illuminated models. Therefore, it is worth studying their characteristics,
advantages, and weaknesses. One of the most widespread CMOS sensors are those
from the Sony IMX series, which are included in large astronomical survey
projects based on small and fast telescopes because of their low cost, and
capability for wide-field and high-cadence surveys. In this paper, we aim to
characterize the IMX455M and IMX411M sensors, which are integrated into the
QHY600 and QHY411 cameras, respectively, for use in astronomical observations.
These are large (36 $\times$ 24 and 54 $\times$ 40 mm) native 16 bit sensors
with 3.76 $\mu$m pixels and are sensitive in the optical range. We present the
results of the laboratory characterization of both cameras. They showed a very
low dark current of 0.011 and 0.007 e$^{-}$ px$^{-1}$ s$^{-1}$ @$-$10 C for the
QHY600 and QHY411 cameras, respectively. They also show the presence of warm
pixels, $\sim$0.024% in the QHY600 and 0.005% in the QHY411. Warm pixels proved
to be stable and linear with exposure time, and are therefore easily corrected
using dark frames. Pixels affected by the Salt \& Pepper noise are $\sim$2% of
the total and a method to correct for this effect is presented. Both cameras
were attached to night telescopes and several on-sky tests were performed to
prove their capabilities. On-sky tests demonstrate that these CMOS behave as
well as CCDs of similar characteristics and (for example) they can attain
photometric accuracies of a few milli-magnitudes.
