How to auto align the moon

[sharp8710]

Hi all,

I want to auto-align my photos and reduce noise and hopefully get more details.

I was shooting the moon the other day at the setting:

Exposure: 1/160 at f/13

Focal Length: 200 mm

ISO: 400

The problems:

I used a tripod but forgot my cable shutter, so the moon moves a lot in the pictures. (e.g. in some pictures the moon will be off centre toward the top left, some other pictures it'll be towards the bottom right)

After corp to 1X1, manually align the moon the Photoshop finally allowed me to run the "Auto-Align" feature, but the moon shifted a lot in the result.

Questions:

Is there a better way to reduce the noise here? How to prepare the pictures so that I can align them perfectly in Photoshop?

Many thanks!!

[JJMack]

Stop the earth and moons movement. Your Camera is on a different heavily body it not on the moon. Does you tripod have a moon tracking system. Your camera should track the moon .

[sharp8710]

Hi, 

Thanks for answering.

The change of moons position inside the frame is because every time I pressed the shutter button, it moved a little bit.

So I wonder if there is a way to align an object (moon) on a plain background (black night sky) when it is in a slightly different position in each layer?

Thank you.

[Chuck Uebele]

Auto align doesn't work well with moon images. Frankly, one of the best ways is to just manually align the images. Change one of the layers to difference blend mode and just nudge the images until the image is totally black or as near black as you can get.

[sharp8710]

Thank you for answering. I tried and manually align works.

Just was kind of hoping Photoshop will merge images to reduce noise and enhance details.

[D Fosse · Accepted solution]

Yes, I'd just do it manually too. The only problem is if you get "half-pixel" offsets. Auto-align will resample in that case, so the result might still be better than a manual nudge.

The reason it doesn't work is that there's usually a lot of surrounding empty space, so the algorithm concludes there's not enough overlap. Which is quite correct; there isn't. 200mm isn't really a big gun for shooting the moon. It's still a rather small dot in the frame.

A way around that is to copy the images and crop tightly, run auto-align, then move the result back to the original image. Then you can just nudge it into place.