Idea for "mini observatory"; anyone tried something like this?

[keenerb]

I get some interesting captures using non-widescreen lens (this one was 65 degrees).

I thought it might be interesting to hack a camera mount onto something like this:

https://www.amazon.com/gp/product/B07TYBS47Z/

and make a little mini observatory that I could point around to various areas of the sky and get what seem to be more detailed shots of smaller areas. Not sure how "useful" it would really be, I doubt I'll have any luck imaging anything dimmer than the Pleides on tiny CS mount lenses, but it might be interesting for some of the brighter objects like pleides, orion nebula, moon/lunar eclipse, etc.

[EricClaeys]

@keenerb With a narrower field of view lens you won't be able to take very long pictures before you get noticeable star trails, which will limit how dim of an object you can get. But since you already have the camera and lens, you can easily try it without the pan/tilt camera.

[keenerb]

With an 8mm focal length lens. Honestly that looks pretty good. It might be a fun and inexpensive little project.

[keenerb]

Haven't taken a new set of darks. Is it just my imagination or can you catch a glimpse of color in the nebula here?

[aleveilleVE2DTL]

Hi keenerb, definitely red. What king of camera are you using?
André

[keenerb]

It's a 120MC-S, which is reportedly a pretty terrible camera but I didn't know that when I bought it...

Bortle 6 bordering on 7 skies. I'm pretty pleased with it overall. I have a raspberry pi HQ camera I use for a 160degree allsky view that I have pretty dialed in and don't want to mess with, but I'll be swapping over to another PI HQ camera and this lens maybe this weekend to do a comparison.

[RobD2FL]

Ive got a Pi4 running an RPiHQ mounted to the pan/tilt kit from adafruit. I do not know anything about coding so I used an old Futaba Rx and Tx from my flying days to control the servos. Still waiting on parts (dome, other lenses, etc) - no pics yet.

[keenerb]

Oh that's interesting, that might be a good cheap middle ground!

[EricClaeys]

@keenerb, I like your 15 second image with almost no startrails MUCH better than the 30 second one, even though the 15 second one has noticeably more gain noise (but not bad).
You can also see the color better in the 15-second shot.
It would be interesting to see shots at lower gain, like 50 or 75, and a slight STRETCH applied via the config/config.sh file. Hopefully the stretch would lighten the sky but keep the stars the same. And if you play around with the red and blue color balance you may be able to see color in Betlejuice (sp).

[keenerb]

Yeah I plan on tinkering with this a lot but the moon is beginning to become a problem...

I'll grab some 100 gain darks tomorrow, I didn't have time today (purchased a new travel trailer) which will eliminate a lot of the grain.

I also want to dial in the nebula location and swap out a 10 or 12mm lens and really zoom in on that sucker...

Here's my setup now:

I've got my rpihq camera in the 4" pvc housing with dome, and I'm using a security camera bracket for manually pointing my 120MC-S, on the end of an 8' 2x2 pole. It's really working well for getting my house, sun awning, and front yard trees out of the allsky image!

[keenerb]

No idea what stretch is supposed to do, but I don't see a difference at all regardless of stretch settings

[keenerb]

75 gain with appropriate darks, 10/10% "stretch" in config.

[EricClaeys]

@keenerb the pictures keep getting better.
STRETCH is supposed to adjust the brightness and contrast of the image, for example, make the darks darker and lights lighter. Someone else reported that they couldn't tell a difference so I'll have to look at it once the next release is out.

[keenerb]

convert "${CURRENT_IMAGE}" -sigmoidal-contrast "${AUTO_STRETCH_AMOUNT},${AUTO_STRETCH_MID_POINT}" "${IMAGE_TO_USE}"

Seems that the syntax for sigmoidal-contrast is AMOUNTxMID_POINT%

convert image-20221005061739.jpg -sigmoidal-contrast 2,90 sig0290.jpg
convert image-20221005061739.jpg -sigmoidal-contrast 2,30 sig0230.jpg
convert image-20221005061739.jpg -sigmoidal-contrast 2,10 sig0210.jpg

All three of these images were identical.

convert image-20221005061739.jpg -sigmoidal-contrast 2x90% sig0290.jpg

Significantly different.

[EricClaeys]

@keenerb thanks for looking into this. Yet another parameter to play with.

I'll fix in the next release.

[keenerb]

Stretching really made it look good I think. I will fix that locally in my scripts and see what next captures look like