MICHAEL W. DEAN

It’s kind of fascinating, and this is how all tracker mounts work, even huge observatories.

You point the base north. Not magnetic north, but geographic north.

You mount it at an angle equal to your latitude. For me that’s 45.13 or as close as I can get.

Then you use the sighter scope, a cheap scope down the center of the motor, to align to the North Celestial Pole. That’s near the Northern Star (Sigma Octantis star in Southern Hemisphere, but same idea.)
Northern Star, Polaris, actually orbits that center visually from the earth.

On other mounts, the sighnter scope is on the side, and/or is a video camera hooked up to a monitor.

That star is not what you center on, it’s what it rotates around. There’s an app that replaces manly math manly men used to do.

The mount does one full rotation every sidereal day. That’s 23 hours 56 minutes 4.091 seconds.

If you get it perfect, the stars will never move in your camera’s view, and you can take long exposures. Those stellar deep space photos can be many hours, or hours over several nights, plus a lot of processing.

My mount, Sky-Watcher Star Adventurer, can do a few minutes solid exposure without drift, when aligned right. Or you can do longer, stills or even video, and fix it with software.

All stunning space and deep space photos have some / a lot of post processing.

See also: How I take Star Photos

I have a new hobby. Several people have asked me how I take these. Instead of typing it over and over, here you go:

Find a dark sky. The lower the Bortle Class the better. Click on a spot on this map:
https://www.lightpollutionmap.info
I live on a farm in a rural area outside a small town, it’s a Bortle 3, so I take these photos off my front porch. But if you live in a 4 or above, you may want to drive to a 3 or lower.

The above photos Canon 90D, Sigma 17-50 f2.8 lens at f2.8, tracker head, 78 seconds exposure, 17mm, ISO 800. Without a tracking head you’ll have a blur that won’t look nice. Because, you know, the world is turning.

The trees and buildings in these are a little blurry because the mount and camera are slowly moving. Some people take a separate photo of the ground and Photoshop it in to make everything perfect, but that’s strange to me for what I’m doing. I’m capturing reality, not making a perfect fantasy. I may do some of those in the future, but I’ll make it clear I’m doing that.

Very dark clear night out in the country.

Used this mount: https://amzn.to/3A4Y6XM and watched a lot of videos about it before it arrived.

If you can afford, get the full kit, not basic kit. I got basic, but now that I understand it, ordered the other parts for advanced.

If the night will dip below the dew point, you’ll need a lens warmer. I use this and a USB power pack.

Had to align mount / tripod using compass (geographic north, not magnetic north), plus (important!) free app “Polar Clock.” to align North Star in little finder scope on mount. Watch this video, also watch other videos on this mount by this guy.

Mount moves slowly. That’s why the buildings and trees are a little blurry. Most people who do this take the foreground separately and “cheat” it in so it’s in focus. Or you can do very long exposures, many minutes, with mount on very slow.

Set mirror to “Mirror Lockup” on camera so it won’t jiggle the photo. Activated camera with intervalometer (make sure you get one for your camera, they are not interchangeable. I use this one for my Canon camera), but just using as remote shutter trigger. Pressing shutter button would shake photo.

Set lens to Manual, turn off optical stabilization, remove UV or any other physical filters. Point camera at stars, focus using Focus Peaking (not all cameras have it. If yours doesn’t, will have to take pix, expand them, and check. Many lenses are at infinite not all the way at the end, but close to it. Different for different lenses, even in the same make/model of lenses from good companies.)

Time lapse photo (90-120 seconds.) Picked the best ones. Did processing in post with Adobe Lightroom Classic. Plus skill and experience with it. It’s the best ones I’ve done and I still see where it could be improved.

Oh, the green in this photo below is a natural phenomena called airglow. It has nothing to do with light pollution, which causes skyglow.