I do a lot of Milky Way photography, but I am fairly inexperienced with shooting landscapes with the moon in the shot. Generally the moon is too bright for the landscape. Using masks in darktable doesn’t seem to be helpful since the detail in the moon is usually blown out. I’ve run across a few posts on the interweb about stacking the moon, meaning take a shot for the moon and another for the landscape, then place the properly exposed moon onto the properly exposed landscape.
A few questions…
Is image stacking the best approach here?
How do I go about stacking properly so the image is seamless and what tools (darktable? gimp?)
Are there other methods / tools I should consider?
I would use hugin’s align_image_stack, then open the aligned images in gimp and blend the two frames together. A luminosity mask may help, but probably just a simple mask with some alpha on the layer should.do the job.
You have something not moving (the landscape) and something moving (the moon). You would have to keep the individual time of exposures very close together.
I would probably use the camera internals auto bracket function for a 5 exposure bracket, and in PP go HDR (darktable has an HDR function, but no image alignment, but I guess you use a tripod anyway). I haven’t used darktable HDR but I guess that approach should work.
I would probably first do some test shots for the proper exposure of the moon, and then set the bracket settings accordingly. And study first how to set bracketing, there is nothing more annoying than looking at camera manuals at night time while shooting a running object.
If you want (various) stacking (functions) with alignment, Affinity Photo still does a 30% Black Friday discount, that will result to $35 - once & forever, not monthly.
Late update after some thinking:
That method is the honest and authentic, real way. The f̵a̵k̵e̵ artistic way would be to replace the background, or at least the moon. dt, rt, can’t be used here. GIMP can. Thinking about it, when you shoot landscape+moon with wide/normal lens the moon will be too small anyway. For a nicer effect I would blend a enlarged moon image into it.
Here is how I would do it with GIMP. Not the most elegant (and I’m sure someone more skilled in GIMP will explain exactly what I am doing wrong), but this workflow works for me.
As you mentioned, if you expose for your moon, you wayyyy underexpose your landscape. (I start with f8@ 1/125 sec). If you expose for the landscape, you blow out the moon. So, take two shots: One for the landscape with your wide angle, then put your best telephoto on and shoot the moon.
In GIMP, select the moon with the foreground select tool (if you have never used it, there is some good doc. on the web.) Save the moon. Then bring up your landscape and tweak it as you like. Then add a new layer, and copy the moon image onto that layer. Position the moon where you want it. Even enlarge it a little if you want (you will have to increase the moon to make the final image resemble what your brain thought you saw.