Laurin Dave

These may work ADM Universal Adapter Block UAB | First Light Optics or alternatively swap the dovetail for one of these William Optics Vixen Style Long Dovetail Plate | First Light Optics FLO should be able to advise if either suitable, also if you haven't done so rotate the scope so that the focuser knobs are on top ..

With my ASI2600mc I use matched Darks for my lights and Bias for my flats, works well as flat exposures are sub 1 second, may need flat darks if using a mono camera with narrowband filters requiring longer exposures. Just measure a bias, flat dark and 10 minute dark and you'll see that dark current is next to nothing although there are numerus hot pixels. Be interesting to see what other do ..

APT 3.84 / ASI native darks problems with ASI 294 MC Pro - Experienced Deep Sky Imaging - Cloudy Nights See this.. have read all the way through but it looks like the issues a t first glance

Nice one Skipper and don't you just love that noisy old KAF16200 sensor and the lovely stars it gives with those gorgeous little spikes ... mind you I also have an ASI2600mc which is pretty good

Caught it again last night so here's a little GIF showing the movement between 00:18 on the 3rd and 23:52 on the 4th .. its moving from left to right Dave

I used this expression "_2021_11_01_19_16_43__14_80_120_00s_0001 - 0.025" in Pixelmath.. I decided on 0.025 by hovering the mouse over the dark, the K value was around 0.0294 (odd coincidence) then again over the light where the min K value was 0.004.. I also added a Pedastal in calibration to ensure that there was no black clipping I used the maximum that Pixinsight will allow which is 1000. You could try the following test at any time. Just set off a run to take 25 darks then 25 lights at the same gain offset temp and exposure but keep the lens cap on for both. Try it with the Native Driver and Ascom Driver and see if the same issue arises with either driver. Let us know how you get on.. Happy to help, modified Dark attached Dave 2021-11-01_19-16-43__-14.80_120.00s_0001_minuspt025.fits

That might be the issue .. I’d suggest you use the ASCOM drivers and see if that provides consistency between your darks and lights

Should just be a bit of rando noise left behind at very low ADU... one for @vlaiv to opine on, Vlaiv may also have further insight into what's going on here

In Pixinsight open "Image Inspection" .... "Statistics" process .. then select the open Dark image .. and it'll show the mean level... it was way higher than the mean level of the light which suggested to me that the offsets were different.. your dark showed no sign of light leakage.

Thanks @Lee_p, I measure the subs with Pi Subframe Selector and generally choose the sub with the lowest median value so long as its got a good FWHM and isn't an outlier. It usually turns out to be the one shot highest in the sky on the darkest night if the subs are over multiple nights.

Thanks Goran, the NSG script (developed by John Murphy, who is a fellow member of Basingstoke Astro Soc) was particularly useful here, it uses stellar photometry to calculate the gradient difference between the target frame and the reference (your choice of best) frame and then subtracts it thereby normalising it the the reference, it then weights the frame against the reference frame and writes the weight into the fits header. This weight is then used when Integrating the subs and helps mitigate the fact the the frames with the best SNR can also have the worst light pollution. The resulting Integration just has the gradient associated with the reference frame, which being only 2 minutes long is easily removed with DBE points in just the corners. Worth a try out (but for your dark skies probably only for when the moon is about - benefits moon-shot Ha too) Dave

The Dusty Pleiades imaged from Berkshire.. taken over three moonless nights in October and early November with an Askar200/ASI2600mc combo mounted on anAZEQ6. 140 x 2 minute exposures at ZWO's LRN setting. Processed in Pixinsight and Photoshop. I used the latest WBPP script with the Split Channels option, after de-bayering this option splits the channels and registers all Red Green and Blue subs separately to the reference frame using thin plate splines and distortion correction. Takes an age but seems to me to produce somewhat better stars with less colour fringing than when registering the subs as RGB. I also used the Normalise Scale Gradient script, which is worth a try out if you haven't done so already. TGV and MMT noise reduction, HSVrepair script, ArcSinh stretch followed by Histogram transformation and Masked stretch then into Photoshop for colour enhancement, a touch of Pixinsight LHE and masked curves to bring out the dust then a final dose of ACDNR in Pi, then resample to 50%. Have to say that I'm pretty pleased with this and the amount of dust, the sky measured mag 20.3 the night most of the subs were taken. A bit of tilt showing lower left.. Thanks for looking Dave

I don't think there's a problem with light leaks. Looks to me as if, despite what the FITS header says, that the offsets are different between the darks and lights (and maybe flat darks and flats although without a flat dark i cant check). I did a quick test using the dark and calibrated flat to calibrate the light but before doing so subtracted 0.025 from the Dark using Pixelmath, I also added a pedastal of 1000 just in case. The result is below which looks fine, well pretty good actually, to me. A mystery as to why this is happening but at least you can do what I did as a work around. Only thing I can suggest is to check the driver settings and that both lights and darks and flats were taken using the same driver.

Yes the dark current and associated would be less at minus 15, but the mean levels in the darks are 1918 vs 520, almost the same ratio as the offsets ie 30 vs 8 which is what you'd expect

Different gain, offset and temp 121, 8, -10 vs 120, 30, -15 may explain that. @scotty38 what does one of your raw lights look like ie is the amp glow clearly visible (I assume it is)

Morning.. have had a look and the mean level of your dark is three times higher than that of your light (explains why there's nothing left but the bright stars after you calibrate with it ) which is a bit mysterious as temp exposure offset and gain are all the same, also your light shows no signs of amp glow and looks like it has been calibrated. I'm not familiar with NINA but is there a possibility that it is outputting calibrated lights?

Best practice is to take darks with the camera off the scope and with its sensor cap on to eliminate any possibility of light leaks, will take a look at your data tomorrow..

Difficult to diagnose without any data so I'd suggest you post up a raw light, a raw flat. a raw dark and a raw flat dark plus your stacked light, master flat and master dark and flat dark for folks to look at. A couple of questions...a) do yo use the same capture software to take you lights and calibration frames and b) do you take darks with the camera off the scope and with the senor totally covered? if not you may have a light leak

Many thanks for the heads up on this Nik, I took 2x10 minutes of it last night just after midnight with my Askar 200 and ASI2600mc, this is a crop from the full frame .. My first asteroid! North is to the left .. Dave

Possibly caused by one of the channels in the flat being saturated because of the colour of your light source. to check I'd look at your master flat, debayer it, split the channels and measure the ADUs across the frame

You can only set it for one I believe, on my GT71 its set to IN.

Looks to me as if your step size is too small and that you have backlash (the cause of the flat bit on the right) , as @Skipper Billy says increase step size so that when the autofocus routine is at the extremes the FWHM or HFR or whatever NINA measure is 3 times larger than when it is in focus ie about 10, to start with i'd set your backlash to 200 or so and see if it removes the flat bit if not increase till it does... Also check all connections are tight Dave

It's the technique Olly's showed me when I was at his place...

I use Pixinsight Star Alignment with Thin Plate Splines and Distortion Correction, you might need to increase "Ransac tolerance" and tick "use scale differences" in the Star Matching box

Hi Adam.. I process the RGB and Lum separately then combine both using either the LRGB script in Pi or else in Photoshop by pasting the lum on the RGB setting blend mode to luminance, opacity to 20%.. increase saturation slightly in the RGB, Gaussian blur of 0.6 on the RGB then flatten .. repeat 5 times.. may not need to increase saturation in the later stages.. Dave