I took a single 10 min sub of M42 last night with my FSQ-106 and SX M26C OSC cam. It was only ever intended to check the cleanliness of the imaging train (M42 dissappears behind trees for me for most of the night).
Judging by the crispness of most of the motes seen in the image (which flats are correcting), would the likely position of these motes be on the chamber window or actually on the sensor itself? I checked the UV/IR filter (spaced 60mm away from the sensor - I use a 67mm UV/IR right in the CAA, rather than at the camera)
I recently pulled the cam apart to clean a grease streak on the window, so it's either that I think, or on the sensor itself (a loupe and a torch aren't revealing anything obvious, nor is using a UV torch)
No need to comment on the noisy nature of this SINGLE 10min sub...it's not even processed apart from an auto-stretch in PI (no flats, darks or biases nor anything else) I also notice I didn't fully get the streak, as evidenced by the small spikes on some stars
This is a single flat, stretched to show the faint motes (much further away from sensor given the shape, grey-scale etc) and the sharper motes (i.e lint and hair )
The darker, well focused motes are generally between 0.76 and 1.8mm from sensor, indicating the sensor cover itself, and the usual round out of focus motes would seemingly indicate the chamber cover, at 5 ~ 6.5mm distance.