In my case the 16" F/4.45 was my first attempt at making a telescope and mirror and it turned out very well. I had a lot of help from John Zeigler and made it as part of his class a few years ago. The best planet views I've ever had were with that scope so it not just a great deep sky scope. It has served and continues to serve me well. Coma is visible but Naglers solve the problem, a Parracor is another option to handle Coma and will provide more flexibility on eye pieces but I used it as a justification to get some good eye pieces. I don't have a parracor, the coma just doesn't bother me that much. I still use lesser EPs and just ignore the coma. I have used big Dobs with ladders and am very glad I don't have to deal with it, it makes observing much more pleasurable. I agree with Erik, 10x per inch is about the optimum magnification for most telescopes in my experience, reflectors anyway, and I find myself drifting back to that magnification after going to higher or lower powers. I've had a total of 3 reflectors and would use the 10x magnification the most with each. I might say that for a good refractor the optimum might be a bit higher than 10x per inch, maybe 15x per inch. Bob ------------------------------ Message: 5 Date: Wed, 7 Jan 2009 17:53:04 -0700 From: "Chuck Hards" <chuck.hards@gmail.com> Subject: Re: [Utah-astronomy] 13.1 inch Coulter Carcass, free To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Message-ID: <2541d8030901071653m4de8dbd8vff7c6c0ab9a5f6de@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 The wrong ladder in the dark can definitely be hazardous, but that's not exactly a problem with a long-focus telescope; it's the wrong choice of ladder. The right choice might not be easily transported, or even easily used at the eyepiece, so that's one of those choices people make. I think the original context of the question was short focal-length mirrors as a first effort at mirror grinding. They do take more work and can be more difficult to figure, but it's not out of reach of the average person, given the proper guidance. If, however, one is purchasing a commercially-made mirror, all the caveats of fabrication can be ignored. I don't agree that deep-sky observing is better at f/4, as a blanket statement. My little RFT is an f/5 and the coma is noticeably less than otherwise identical telescopes I built at f/4, yet the field isn't much smaller using the same eyepiece. I also don't weigh my equipment choices against their fit at a public star party. I'm kind of selfish with my astro-time- my personal enjoyment is my prime motivation. I'll blow-off being "star-party correct" in a heartbeat if I feel I can get some kind of advantage by doing so. On nights when I'm specifically doing the public outreach job, then convenience and safety will trump imagery out of necessity. The telescope must be designed for it's intended use. One person's trade-off list will probably not correspond one-for-one with someone elses. On Wed, Jan 7, 2009 at 1:59 PM, <zaurak@digis.net> wrote:

The narrow steps on a ladder can take a toll on your feet in the course of a night. The classic dobson is long focal length, but there are many companies that do a good job on fast optics in the 4f range. Deep sky observing is better with f 4's.

Tall ladders seem a liability for public star parties.