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Originally Posted by ballaratdragons
even the best of mounts will not keep an avi perfectly centred,
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Alignment is pretty critical at high magnifications of course, but an Orion Nebula as pictured on his website could be doable. Doable yes, advisable no...
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A stacking program needs to be able to lock onto a chosen point (or several points) to account for small mount errors and atmospherics (seeing, etc).
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The stacking phase does not involve such a thing, because that procedure is performed in the alignment phase. In Keith's defense (if this is indeed the case), to publish & sell a stacking program that does not align is acceptable, but admittedly fairly useless when it comes to astrophotography. It may be useful to improve the SNR when doing more earthly low light photography though.
EDIT: One of the features is indeed; "Translationally and rotationally aligning the frames", so it sounds like something might be going wrong there.
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How do I align images?
There are two forms of image alignment: translational (sliding around) and rotational. Translational alignment can be done in three different ways: difference, centroid, and cross-correlation. If you want to keep things simple, just use the difference method and don't sweat the details. Rotational alignment can only be done using the difference method.
The first thing to do is define an Operation Bounds Rect. This is a rectangle that specifies an area where the frame being aligned will be compared to the reference frame (the first frame in the Clips Window). Start by making sure no clips are selected (Deselect All from the Edit menu). Then shift-click one clip. Conventionally one would use the reference frame, so shift-click the first clip in the Clips Window. Move to the Frame Inspector Window. If it is blank, you don't have exactly one frame selected. Try again. Otherwise, click-drag a rectangle in the Frame Inspector Window to define the Operation Bounds Rect. I recommended that you keep the Operator Bounds Rect small (to speed the alignment process up) and include edges and other interesting areas of the image in the Operation Bounds Rect (this will make alignment perform better).
Now you are ready to align the frames. Deselect all the frames (Edit menu). To align a single frame, hold down the '1' key (large distance difference alignment) and click one clip in the Clips Window. It will autoalign. If the alignment isn't very good, give a second or third try, it may converge on the proper alignment over a series of repeated attempts. Alternatively, you might consider defining a different Operation Bounds Rect or manually nudging the clip closer into alignment (sloppily and quickly) before running autoalignment again.
To align multiple frames at once, shift-click or shift-click-drag a selection of clips in the Clips Window. To align all the frames choose Select All from the Edit menu. In either case, multiple or all, hold down the '1' key and click on any selected clip. They will all autoalign.
To perform rotational autoalignment, use the '6' key. Rotational autoalignment will align minor rotational misalignments better if the Operation Bounds Rect is not near the center of the image. Think about it, it makes sense.
Looking at the manual, KIS sounds pretty damn powerful...
