There are two basic types of telescope mountings: altazimuth and equatorial.

Altazimuth Mounts

Dobsonian Altazimuth Mount

Altazimuth is a contraction of "altitude" and "azimuth". An altazimuth mount moves in two axes - altitude and azimuth.

The altitude axis points the scope vertically above the horizon.

The azimuth axis points the scope in a horizontal direction around the horizon, much like the pointing of a compass.

Movement in altitude and azimuth will allow the scope to aim at any point in the sky, but to follow an object as it moves across the sky, you must move it in both axes at the same time.

A Dobsonian mount is an example of an altazimuth mount. Many modern computer-controlled fork mounts, both single and double arm, are altazimuth mounts.

It is possible to take planetary images with a basic hand-driven Dobsonian mount, but as you increase the magnification, it becomes increasingly more difficult to keep the object in the field of view. This makes it especially difficult to do high-resolution planetary photography.

Single Arm Fork Altazimuth Mount

For example, I have shot Saturn with my 12.5 inch Dobsonian telescope with a 3x Barlow at 5,525 mm of focal length. It was extremely difficult to move the scope by hand to follow Saturn as can be seen in the video below. If you try to lead the planet so it just drifts through the frame to minimize blur from the scope movement, then the planet is not in the frame very long as it drifts by. So you don't get a lot of frames to use in lucky imaging. You can try to splice several videos together to give you more frames, but sometimes software has a hard time with objects that move around a lot. It was not any fun trying to image at a high magnification with a Dobsonian, and I would not really recommend it, although you are certainly welcome to try!

Yes, it is possible to do high-resolution planetary photography even with a non-tracking Dobsonian altazimuth mount. But it is not easy. The scope was pushed and pulled by hand to try to keep Saturn in the frame. The video was shot through a 12.5-inch f/6 Dobsonian working at f/18 at 5,715 mm focal length with a 3x Dakin Barlow. The video was shot with a Canon T2i (550D) using 640 x 480 movie crop mode at 60 fps. The best 1729 frames from 5701 total were selected and stacked in RegiStax. The resulting image is at right. Shot on March 25, 2011, it shows remnants of the "Serpent" storm in Saturn's north tropical zone at top left on the ball of the planet. This is not the entire video, it was edited for time and resized to make a smaller file to show here.

A computerized altazimuth mount will track the planets without any problem. You will get field rotation, but exposures are not that long, and the planet will be in the center of the field. Field rotation is where the entire field of view rotates around the center of the field. It is usually not noticeable if you are using the scope visually. Most planetary image processing programs can deal with a little bit of field rotation in videos, but it depends on the image scale you are using and the length of the video.

Some altazimuth mountings can be turned into equatorial mountings by the use of a "wedge". Dobsonians can be used on Poncet platforms to do this. Altazimuth mounts can also use a field de-rotator mounted in the focuser to avoid field rotation.

Equatorial Mounts

Computerized tracking Go To Equatorial Mount

An equatorial mount also has two axes.

The polar axis is aligned parallel to the Earth's axis of rotation by aiming it at the north or south celestial pole. It's easy to find the celestial pole in the northern hemisphere because it is close to Polaris. It is a little harder in the southern hemisphere because there are no bright stars nearby. Some mounts have a polar-alignment scope built into the polar axis making polar aligning easy.

The declination axis is at right angles to the polar axis.

You can aim at any point in the sky by moving the scope with these two axes. The difference between an altazimuth and equatorial mount is that once you have acquired the object with an equatorial mount, you only need to move the scope with one axis, the polar axis, to follow an object. You do not have the problem of field rotation with an equatorial mount.

The polar axis moves the telescope in right ascension, and the declination axis moves it in declination. Right ascension and declination are imaginary lines projected on the sky like lines of latitude and longitude on Earth.

Tracking Mounts

A tracking mount is motorized so that it follows celestial objects as they move across the sky due to the Earth's rotation.

Both altazimuth and equatorial mounts can be motorized and turned into tracking mounts.

A tracking mount makes planetary photography much easier.

Computer Controlled Go To Mounts

Specialized computers with high-speed motors can control both altazimuth and equatorial tracking mounts. Once these mounts are aligned and initialized so the computer knows where it is initially pointing as a reference point, you can direct the telescope mount to "go to" any object that is visible in the sky at that time and the computer will slew the scope at high speed to the object.

Computer controlled go-to mounts are not really needed for planetary photography, but the convenience is quite nice. Go-to altazimuth mount still suffer from field rotation, but since planetary exposures are usually short, this is usually not a problem.