>>4342450>it was just the cheapest typeAh - you must be thinking Dobsonian. This refers to the mount, not the scope itself - the least expensive and easiest to make at home. All Dobs are reflectors because a refractor would be limited to low-altitude objects on a classic Dob mount. Anyway... it's an Alt-Az mount, which means the field of view will rotate in long exposures. They can still be used for shorter exposures, as with solar system objects or bright nebulae. There are two ways to mitigate rotation:
1) Field de-rotator. It's like a star diagonal with a motor what rotates internal mirrors to counter-rotate the effect of Earth's rotation. It's an expensive device (minimum $800).
2) Equatorial hybrid Dob mount. This is basically a Dob mount tilted at the same angle as your latitude. You need to polar align it, and it's hard to do.
Pic related: a large amateur scope (18") on a home-made Dobsonian mount.
