In the case of captures taken over many hours with a star tracker, is it necessary to correct the orientation of the images before stacking so that they are all oriented in the same way?

In theory you don’t have to flip any image (and even less if you stack in RAW).

Nebulb always performs the stacking with all images oriented the same way, but this is something that Nebulb manages internally based on the information of the images and their metadata (where the camera orientation information is).

Thus, the only thing you may have to do (when importing images into Nebulb) is to select the orientation of the base image (if it does not have the orientation you want).

In that case, before stacking, you simply have to orient it to your desired orientation (with the top right flip buttons) and Nebulb applies that same orientation to all the images in the stack (without having to do anything else).

For example, this is what I get in Nebulb when I load a stack of images captured with a star tracker for more than 6 hours (time during which the camera has completely changed its orientation):

But since I want Orion to be vertical, I simply apply a flip to the image (before stacking) and Nebulb already takes this orientation into account for the rest of the images in the stack (regardless of the fact that there could be images with different orientations):

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Updated on 11 de January de 2024