A Rant About Aperture

There is a scourge in amateur astronomy and it is the notion that you need a big telescope. The argument goes something like this, the larger the light collecting area of your the more you can see visually, and the shorter your exposure times will need to be. This is the type of conventional wisdom that gets people into a lot of trouble.

In order to image you must compensate for the movement of the earth, the result being that you need a mount or platform to track the area of the sky that you are trying to look at or image. This leads to a problem since equatorial mounts have weight limits. The result is ridiculously large mounts and telescopes, or telescopes with equatorial platforms.

This leads to a razor I have come upon in my time as an amateur astronomer, the number of times per year you use your telescope is proportional to its moment of inertia. As evidence I present the preponderance of used telescopes on astromart that say "used a few times" or "only used once." My personal experience had to do with the purchase of an 10" LX-200 ACF  which really should not be handled by one person. While sturdy in Alt-Az mode, the telescope weighted so much that I could not bring myself to use it that often.

Indeed a large swath of telescopes I would simply not recommend for this reason. Any telescope on a fork mount is cumbersome over 9.25" it is quite nearly impossible for one person to set one up safely. 8" telescopes have been used for time and memorial but we now come to the elephant in the room, what are you using this thing for exactly?

If you are using it for visual astronomy, you will be constantly let down since almost all deep sky objects that you see on APOD or in text books have been taken with some sort of digital camera. The result is that at the eyepiece you see almost nothing or something lacking contrast and color. The end result of any attempt at satisfying visual astronomy leads to a truss tube Dobsonian over 30" in diameter. We then come to the other elephant in the room which is the fact that you cannot use such an object anywhere near your home, unless you live in the middle of nowhere.

Hence, Visual astronomy is a hard nut to crack so that you end up with a very large telescope which is as complicated to set up as an equatorial telescope and that you can only  use once or twice a year at a dark site. The other option is to go to imaging, which you can do with a modest setup, which you cannot under any circumstances use for visual astronomy save for the occasional dark sky expedition. The reason that aperture does not matter for imaging is that your interested in collecting enough photons. The way you collect the photons is usually with sub frames and a digital camera far more sensitive than your iris. So you must pick your poison, either you have a light imaging setup or a big dob you lug to dark skies, anything in between is just a waist, for anything except viewing planets of course.

The reason I am posting at 4:42am on a Friday is that I have a sleep study tomorrow, so I have decided to stay up until its time to finish that.