Janusz "..30º to the west, if you started with 30º to the east..." Looking at the diagram, shouldn't I slew 60degs West from my
starting position at 30degs in the East, to complete the PA. Wouldn't 30degs only, put the mount back in the "top dead center"?
Sorry. I probably made an error explaining it. The mount will move about 60 degrees, not 30, once you tell the polar alignment to proceed.
Exposure times - my camera 533MC, OTA FL 420mm. f/5.8 (no reducer as of yet) the NPF calculator suggests 0.45s exposure for no trails and no tracking. I'll certainly experiment with 1 and 2 seconds and hope ASIAIR do its magic and plate solve.
That is a terrific camera. I have the ASI2600, which is from the same family. The 2600 completely obsoleted my ASI071 Pro that I haven't used the 071 after taking the first image with the 2600. I have the bigger brother, the full frame ASI6200 on back order with my dealer. My plan is to use the full frame in the APS-C sensor ROI mode and use it instead of the ASI2600, just to get faster downloads when I don't need a large FOV. It will be used on either the Tak FSQ-85 with 1.01x flattener, or on the Askar ACL200, both of which should handle a 44mm image circle when I want a wider FOV than today. The Askar 200mm really works very well already framing both Heart and Soul nebulas for example, on the ASI2600 already. I sort of feel guilty buying the ASI6200 when it will be rarely used in full frame mode :-). But when you need a larger FOV, there is just no way around it (currently building up a Sigma 135mm ART lens and ZWO EAF combination for even wider field :-).
These (533, 2600, 6200) cameras have what Sony calls the High Conversion Gain (HCG) mode that reduces read noise crazily without reducing the dynamic range by much.
ZWO does not provide an interface (not even in their current camera SDK) to explicitly turn HCG on. But if you look at the documentation for the ASI533, you will see a sudden decrease in read noise at gain = 100. What ZWO does is to implicitly turn on HCG when you set the gain to 100 or above.
Unless you need that extra 1/4 of an f-stop in dynamic range (in which case, use gain = 0), I would highly recommend that you use gain=100.
Gain above 100 is really not useful for this series of cameras. The read noise does not decrease much any further, and the dynamic range keeps falling.
There are very few instances where that 1/4 f-stop is useful.
So, just set the gain to 100, close your eyes, and start shooting away.