In this tutorial you'll see how to use the Camera module to prepare your astrophotography session.
In my workflow, this is usually the second step, after connecting INDI Server and devices, primarily to focus, and to see if I can identify the target in my field of view.
If not (as it often happens) and I can't identify the current field, I then go to the Plate Solving page, to get an idea of where I'm currently pointing, move my telescope to the actual target, and then go back to the Camera module.The Camera page has all the controls to let you shoot and examine pictures:
You need of course to select a camera in order to shoot images. This can be done by clicking one of the buttons corresponding to your camera name.
You can also select a filter wheel in the same way, so you will be able to change filter before shooting.
Just enter a valid exposure time (in seconds) in the Shooting text input. The shoot button will then be enabled.
If you selected a filter wheel, you can now also change the current filter if you need that.
Then just click shoot whenever you want to grab an image.
The continuous shooting control will loop shooting again as soon as a new image is downoaded.
Using a Bathinov mask (or similar focusing tools) is recommended.
I usually focus on a single star, using a Bathinov mask to assist me getting as precise as possible.
The best way to focus with this method is to select only a small region of the image surrounding the star, and enabling continuous shooting. The first can be done using ROI.
The Select ROI button will allow you to select a rectangle on the image. To help you selecting a more precise region, zoom will automatically revert to 1:1 (real size).
ROI settings will apply to the next image, so when you're done selecting a rectangle, click again shoot
As soon as you're happy with the region selection, you can enable continuous shooting.
Just click the Continuous slider. When this is active, and you start a first shot, the app will start shooting again every time a new image is downloaded.
This allows you to go "hands free", getting automatically new images while you adjust the focuser, until the star is properly focused.
When you're finished, click again the Continuous slider to disable Continuous shooting.
Just click the reset ROI and shoot again to get a new full size image.
After focusing, it is time to start pointing at the right coordinates.
If you're lucky, you might already be very close to the target area you want to shoot, so you will only need minor adjustments. If not, the Plate Solving module can assist you in that matter. Just visit the tutorial to know how to use it, then jump back to this section.
You don't need anything special to do field adjustment: just shoot an image, and see if the stars match the coordinates you want to point to. You can increase exposure a bit to see if it helps spotting faint objects as well.
Binning is something else that can be very handy: not only can help in showing more objects, but it will also reduce the image size (and then speed up image download time).
I usually go back to the INDI Control Panel, increase gain on my camera to a very high value, then go back to the Camera page, set binning to 2x2 or 4x4, and start shooting and moving my telescope until I get my target into the field.
You can use the Camera page also to choose the correct exposure.
First you want to make sure that all the camera settings are in a good shape inthe INDI Control Panel (for 16bit and gain for instance) and that you set binning to 1x1 again (or the value you want to use for binning in the sequence, anyway).
You should then enable Histogram using the Show Histogram button.
The histogram plot will update every time you shoot a new image. You should adjust your exposure time (and eventually gain as well) based on how the curve falls into the limits of your plot.
Ideally you should try having no clip both on low and high values (no pixels with value too low, say below 100/200, and no pixels too high either).
You can now start creating a sequence using the Sequences Module.