Besides scopes, mounts and cameras I would say.
Here's mine: the Baader Varilock
If there's something that in 3 years of Deepsky imaging brought me to the brink of tears, these are the "cheap" extensions (cheap only for quality, not price) locked into each other, into my filter wheel, into my camera.
I had to rely on calipers, a bench vice, WD 40 a freezer and even a saw for metal to remove them.
So in the opposite way this piece of equipment brings me great satisfaction every time I have to rely on it. It's a great extension, easy to use, good material, it may work also like a field rotator and the letters written on it are a very good reference for the camera positioning into the focuser. So... what's yours?
Edited by Epox75, 23 May 2020 - 08:09 AM.