Beginner stacking question.

[sorrycharlie]

Excuse me if this is the wrong spot for this question. My first post here and I’m a complete beginner. My question is regarding image stacking. I understand the principle and the process but what I’m confused about is if all the images need to be framed exactly the same. I see images where people have taken hours worth of images that would need to be spread over multiple nights, which would require the subject to be framed the same way each night? And also mounts that aren’t super accurate or aren’t polar aligned correctly would get some image drift over time right?
So my question is, does the image stacking software basically see the repetition of the subject and then align them all for you?
Sorry if I haven’t explained my question very well but it’s tricky to articulate exactly what I mean.

[Mickoid (Michael)]

Most people who take the same object over several nights will be using plate solving software when capturing. This basically references the following night's framing with the initial first night framing. You can do it manually but it can be tricky and time consuming. In so far as individual sub exposures in a single session, there may be a slight drift between them but the stacking software will register to the star positions not the framing. The result may require cropping the image to eliminate the overlapping framing around the edges of your image, depending on the amount of drift during exposures.

[sorrycharlie]

Yeah ok, I now understand, thanks very much for the reply.

[xelasnave]

Deep Sky Stacker does not mind how poorly framed and I often put subs in some right way up some upside down . You will see where they don't line up on the final image and just crop to take everything that is when n common.
Get Deep Sky Stacker a free download and start stacking...sorry it's for Deep Sky I am not sure of the most popular planetary stacker but I once used Registax it was as free.
Alex

[Startrek (Martin)]

As mentioned, when imaging over multiple nights you can use plate solving or sync based Goto to ensure your target is closely framed and aligned each night
Deep Sky Stacker ( DSS ) is an excellent popular stacking program ( free download ) to stack and align your deep sky images
Even if your frames are not aligned by a considerable margin ( eg: 20 to 30 pixels ) or your image is inverted due to a meridian flip, DSS will align and stack the data and produce a final image that just needs to be cropped slightly to remove perimeter stacking artefacts.
For Planetary imaging Autostakkert 3 is an excellent stacking program which is also free. The AS stacked file can then be processed using Registax 6.

Attached is some documents I put together for both DSS , AS3 and Registax 6

Cheers