PixInsight - aligning two images of very different scales

[Filroden]

I'm trying to use staralignment on two images of M42 but it can't find enough pairs in the second image, which has a much smaller field of view. Is there something I should be doing?

I've tried relaxing some of the settings but I get the same issue every time.

for info, these are the two images.

 

[Barry-Wilson]

Try using DynamicAlignment setting image 1 (the reference image) to the smaller scale (ie M42) and image 2 (the target image) to the larger scale M42 & Running Man.  Carefully select a star in the corner of your M42 and match it in the larger image; repeat for stars in each corner and one central one, then apply the instance to the target.

HTH.

Barry

[Filroden]

Thank you. I did look at dynamic alignment but I couldn't see how to select the corresponding star on the second image. It would only select in the first image. Is there something you need to do to swap between them?

[Barry-Wilson]

When you select a star on the reference image, PI places a cross where it thinks the star is on the second target image.  Invariably this is incorrect if there is a significant difference in scale.  You simply click on the cross and drag it over to the correct star (like a drag and drop windows technique).  The second star choice may be closer, the third should be correct.  I would choose at least one star in each corner and one in the centre.

Good luck!

[Filroden]

Thanks again! That worked. I don't know how I missed seeing the targets on the second image  Now to learn how to seamlessly blend the results.