I made this to show people who know nothing about Astrophotography what equipment is involved.
The Rig- The Mount is an iOptron CEM26. Its job is to precisely cancel out the Earth's rotation so the telescope can follow the target across the sky.
- The Telescope is a ZenithStar61. It's not too different from a photography lens; it has a focal length of 360mm and an aperture of f/5.9
- The Camera is a QHY183M - this is a monochrome cooled camera. Cooling the sensor helps achieve lower noise in the long exposures needed for astro work.
- The Filters are enclosed in a motorised wheel between the camera and the telescope. They filter the light reaching the camera sensor to specific wavelengths or colours needed for the target being imaged.
- The Guidescope and camera on top help keep the telescope pointing exactly at the target. It's continuously watching for any hint of drift or wobble in the pointing of the telescope, and immediately issues correction instructions to the mount if needed. This way, the amount of wobble or variation is kept to between one and two pixels in the main camera.
- The Focuser is needed because as the filter is changed, it becomes necessary to re-focus. You want the focus to be as accurate as possible, so on each filter change, it takes a series of images adjusting the focus a little bit at a time (this thing has micron-precision) until it works out the best sharpness. It'll also stop imaging and re-focus if the temperature changes by more than 2°C
- Finally the Heating Strap is needed to keep the front of the telescope and guidescope warm enough to prevent dew forming on it during the night.
Everything is connected to and controlled by a dedicated laptop computer that sits outside all night with the rig; this software is clever enough that you can point the telescope at any random location in the sky and take an image, and the computer will work out exactly where it's pointing from its own internal map of the sky.
The rig stays out all night, as the process involves taking many long-exposure images of the same target so that they can be stacked and averaged later; this eliminates a lot of camera noise.
- The value of all this equipment (excluding the computer) is $NZ8000 / USD 5000 / £4150 / €4700
- This would count as an entry-level narrowband astrophotography rig. Pretty much bottom-of-the-range everything. You can spend tens or even hundreds of thousands of Dollars
The processThe process for shooting astronomy photographs is a bit more complicated than getting a
Really
Good
Telescope and putting an iPhone camera up to the eyepiece....
- Set the rig up in the backyard and align the mount carefully to the point above the South Pole (where all the stars pivot around)
- Select the target carefully, one that will be up for most of the night (consult planetarium software or personal knowledge)
- Select the best exposure strategy (broadband or narrowband or a mix of both?)
- Line up the telescope to the target and start the mount's tracking motors
- Run auto focus routine and start the camera cooler
- Program in the number of exposures and length needed, considering how long before the sky starts to get light or your target sets
- Start the automatic guiding to keep the mount exactly on target
- Begin exposure plan - go inside and monitor from computer inside!
Next Morning....
- Bring the gear inside
- Download the images
- Stack images for each filter individually, rejecting any bad ones that clouds came across or satellites streaked through
- Process the images adjusting contrast and lightness and adding appropriate different colours for each channel
- Share pictures on Social Media to exclamations that I must have a Really Good Telescope
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