My personal experiences with a 6" f/8 APM ED as a planetary instrument are positive, but there are some caveats:
- it's a fairly large scope and needs a beefy mount, if you want to take advantage of the good optics and use high magnifications.
- the pier/tripod needs to be fairly tall, even if you observe seated. It's a long scope.
- it needs substantial cooldown! This must NOT BE IGNORED. This means that it is not an instrument to use at a moments notice, unless you can house it in an observatory. If taken from indoors out in a cold night, cooldown takes well over an hour. The glass is very thick and steeply curved. If at all possible, I plan ahead and let the scope sit outdoors for a while, before starting observations. For lower power observing (below 100x), this is not necessary.
- if used with this in mind, I've found it to be a very reliable performer. Much more so than the C8 I once had.
- it requires unusually good seeing (for my location) to show everything it's capable of.
- it likes to dew up at the most inconvenient times, so have the hairdryer ready. Or make an additional dewcap.
- In addition to it being a fine lunar-planetary scope, it's a SUPERB deep-sky scope, despite its modest aperture.
- It's also a superb solar scope, when outfitted with a Quark Chromosphere.
6"-class refractors are not everyone's cup of tea, but they can be very pleasing telescopes to use, if you understand their needs and behavior. I find them to be a very good balance between portability, power, reliability, versatility and relative affordability. They can do a lot of things really well.
Taken with APM 152/1200 ED and 4mm KK ortho, handheld Sony Xperia phone. No image editing whatsoever.
Clear skies!
Thomas, Denmark