First attempt using an astro-specific stacking app

[rcreamer]

Here are the first astro images I've stacked with a non-Photoshop stacking program: Astro Pixel Processor (on MacOS).

I'm having to grapple with steep learning curves: 1) the stacking app itself, and 2) best exposure settings.

Both images were taken with an A7R5 and the 70-200mm ii Sony tele on a Sky Watcher GTi star tracker. A Bahtinov mask was used for focusing.

[Update: I'm including a photo showing what it looks like when focusing using the Bahtinov mask. When you point the camera with the mask over the lens at a bright star, you see a diffraction pattern with two criss-crossing lines along with a 3rd line which moves roughly up and down when you adjust the focus ring. When the moving line exactly bisects the two criss-crossing lines, the lens is theoretically in focus. This tool can also be used for regular low-light landscape work with distant lights, btw. Some Bahtinov masks are too coarse to work with wide angle lenses, fyi. The one I got has lines that are fine enough to work with my 14mm Sony prime. I got mine at Johannes Scientific for $35.]

I still have a lot to learn and also need more hours of integration time

At least I'm starting to see star colors vs my earlier attempts.

Here are the exposure details for the two attached images. (I'm not taking any calibration frames yet.)

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M31 - The Galaxy in Andromeda

(40) 120-second exposures at ISO 800, 200mm lens, f2.8

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The Pleiades Star Cluster

(70) 120-second exposures at ISO 800, 200mm lens, f2.8

• ILCE-7RM5
• FE 70-200mm F2.8 GM OSS II
• 200.0 mm
• ƒ/2.8
• 2.5 sec
• ISO 8000

• notAvailable
• 8399 sec

• notAvailable
• 4680 sec

 

[THXGEEK]

Those are really good!

Are you near any major sources of light pollution (i.e. airports, big cities, etc)? I am in suburban Northern Virginia (near Dulles airport) and the sky glow here is awful (Bortle 7.5). I'd have to drive for an hour just to find decent dark skies....

 

[THXGEEK]

Light Pollution Map.

 

[rcreamer]

Those are really good!

Are you near any major sources of light pollution (i.e. airports, big cities, etc)? I am in suburban Northern Virginia (near Dulles airport) and the sky glow here is awful (Bortle 7.5). I'd have to drive for an hour just to find decent dark skies....

Thanks. I live in a Bortle 4.5-5.0 area (California foothills). These were taken from my living room deck There's actually a lot of sky glow in the north and northeast but these targets were south of this a bit. I can get rid of a lot of that in LR by lowering the Blacks, but you have to try to keep it real. Since I can only experiment/practice a few days each moon cycle, it's going to take me months to get better and try new techniques. I can drive to Yosemite in 2 hours where the skies are pretty dark and hope to give that a try soon. I got a Jackery Explorer 300 v2 power station to power my star tracker and a7r5.

 

[Richard A]

Great stuff! Well done.