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Peter,
If your Flats and Bias have been captured correctly in APT and stacked in DSS accordingly, you will still have issues in Startools if you don’t follow the operational flow chart on the left
Since you are using a 150mm scope at focal length of 1050mm ( assuming no reducers etc.. ) with the 2600MC , your image scale should be as follows -
3.76 uM x 206.3 / 1050 = 0.73 arc sec per pixel which is oversampled
With oversampled data you are encouraged to Bin in Startools to trade off some resolution for noise reduction. A default Bin of 50% works really well and also has 2 added bonuses , your stars will remain round ( not blocky when you zoom in ) plus the image size is more manageable to work with. Your not waiting for the computer to process the task
As Fred mentioned , cropping your image for stacking artefacts and other anomalies is so important before you apply a Wipe and then second or final stretch of the image.
So you should follow the flow chart on the left in Startools -
AutoDev ( forget Film dev ) 1st stretch to inspect image
Bin default 50%
Crop edges or areas to remove stacking artefacts
Wipe default but bump up dark anomalies to say 4 pixels
Then second or final stretch with Autodev using a Region of Interest ROI ( drawn with your mouse around the main body of the object ) Adjust “Ignore Fine detail” slider and “Outside region of interest “ slider a bit to adjust detail and brightness across image
After that you just move on to Contrast , HDR , Sharp and so on ….. to complete your processing
Attached is an image of M17 I captured 2 weeks ago under Sydney’s horrible LP using 3 minute subs ( 3 hours of data ) , dithering , Gain 100 , cooled to - 10C , Flats and Bias stacked in DSS
First image is just loaded into Startools and AutoDev for inspection
2nd image is initial stretch in AutoDev then using Wipe without Bin or Cropping
3rd image is initially stretched in AutoDev , Bin , Cropped and Wiped
4th image is initially stretched in AutoDev, Bin , Cropped , Wiped and second stretch in AutoDev using ROI and sliders ( ignore fine detail 4 pixels , outside region of interest 10% )
You can see the mess you end up with if you use Wipe without cropping out artefacts and other anomalies
Hope the above helps
Cheers
Martin
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