You probably build the PiFinder you are going to use, but if not, here's a quick overview of the unit.
One side has the keypad and screen, while the other has the camera, lens and camera mounting cell. There is likely also a GPS transciever plugged into one of the USB ports with an antenna mounted on top.
Depending on how your unit was built it may have internal batteries or it may be powered from your telescope through the available USB-C port.
In the photo on the left above, you can see two of the three thumbscrews used to tilt the camera mounting cell. These thumbscrews allow alignment of the camera with your telescope optical axis after it's mounted.
Depending on the mounting system you printed or received for your PiFinder, you will either have a rail on the bottom which fits a standard finder shoe, or a Go-Pro style mount. As with any finder, a sturdy and stable mounting method is needed; Ideally with the ability to take off the finder and re-attach it while retaining it's relationship with the telescope.
After you mount your PiFinder the first time, you'll need to setup the camera aperture and focus. If you are using the recommended lens, it will have two adjustment rings on it; One to adjust the aperture (f-stop) and one for focus.
Make sure the aperture of your lens is all the way open. For the recommend lens, turn the f-stop ring towards you all the way if you are looking at the unit like like the image above.
Focus for plate solving is actually not all the critical, and defocusing a bit can even improve the solve as it spreads star light across multiple pixels. You can either use a very distant object during the day, or a bright star at night. Start with the focus ring all the way to the 'Far' end and you'll probably be close enough to solve most areas of the sky. Better focus may help pick out a few dimmer stars and allow you to potentially reduce exposure time.
There is a focus helper in the Preview options to help. This will show a zoomed in image from the center of the camera view to help you hit focus on the small screen. To activate the focus helper, hold down the 'A' function key while in preview mode and turn on the option from the settings menu. As you adjust the focus ring, you'll have to wait a second or two make after each adjustment to see the results in the exposure.
Once your PiFinder is mounted to your telescope, you'll need to align it with the optical axis of your telescope just like a RACI or red-dot finder. To do this, you can use the three thumbscrews at the back of the unit to adjust where the camera is pointing:
- To start, point your telescope at a distant object or bright star and center it in your telescope eyepiece.
- Turn on the PiFinder if it's not on already
- Make sure your PiFinder is in Preview mode so you can see what the camera sees.
- If you are doing this during the day, you'll need to use the DN key to reduce the exposure
- Use the three thumbscrews to adjust the tilt of the camera. Between each adjustment, make sure you wait for a new exposure to be taken to see the results. This normally takes about 1.5 seconds (at night), depending on your exposure settings.
- If the PiFinder is not holding alignment between observing sessions, try tightening the middle screw, or selecting a stronger spring, to help hold the cell more tightly against the thumbscrews.