Longshadow wrote:
As wide an aperture as you can get to let as much light in as possible. I use a 50mm ƒ1.4. Wide/tele depending on how much of the sky you want to capture vs. the aperture available for that focal length.
Tripod with remote shutter release.
After about 15+ seconds you'll start getting star trails.
Lens hood to keep stray light out.
Works best in a dark area, otherwise neighbors lights can cloud the image.
Possibly up the ISO.
Experiment for your camera.
This advice about setting the aperture as wide open as possible doesn't work well with many lenses. And some it does. Stars are point sources of light and really challenge a lens. And problems such as Chromatic Abberations (CA) can show up. And coma distortion. And astigmatism distortion. And on and on, I could go.
And cost of a lens isn't always a good indicator too. Some lenses are just better at this than others.
The web site
www.lonelyspeck.com has lens recommendations.
One thing I have found is that using a narrow band pass filter helps a lot. I had the CFA removed from the sensor turning the camera into a mono sensor camera. And when you can limit the range of wavelengths going through the lens, CA problems go away. But not everyone has such a camera.
Stopping down a few notches can greatly reduce lens distortion problems. But now you have less light, and need longer exposures.
And then there are lenses that just happen to be good wide open for these shots. These are a delight to use.
Next problem is focus. I really dislike focus-by-wire for stars. Much prefer old fashioned manual focus, and especially lenses that use a lot of focus ring rotational travel.
And I have found macro lenses tend to work really well too.
It is OK to up the ISO too. Noise reduction SW like Topaz's Denoise AI can save the day.
I am attaching a lens that does work well for stars. This is the Olympus 12-100mm f4 lens, and used at 100mm and wide open at f4. This was shot using an Olympus EM1ii and consisted of many shots that were stacked. Each shot was 6 sec and for this image, I did not track. If you zoom way in, you can see tiny star trails. This is Comet Neowise that was in the sky 2 years ago in July 2020. I used ISO 3200 for which the stacking helped with the noise and then I did some stretching in curves in Photoshop and some Topaz Denoise AI. And by the way, this is a focus-by-wire, and happens to be an exception to my rule about focus-by-wire. Olympus did a great job designing this lens, and distortion with stars is under control.
I have many other lenses that are not so good at stars. But I don't like to show those.