Originally posted by GaryML That 225mm Cassegrain sounds nice. I always wanted to try a bino-viewer. The sky conditions are not very good where I live, so I need portability for the opportunities when I can go to dark skys (in the mountains and desert east of the city). I used to have a 200mm Newtonian on an equatorial mount. It was just too big to take on any sort of trip, so I switched to smaller scopes. The 100mm refractor I have now is probably the maximum size I can transport with ease.
Yes, I think the sensible limit is 100mm for a portable scope. Add the mount and paraphernalia and you are arriving at 15kgs all in all, anyway. I use either the tiny Pentax 75 or a slightly bigger 100/600 Semi-Apo on an old Vixen SuperPolaris mount, when I need to be mobile. The Cassegrain (by the way, its 250mm, I got it wrong in the last post) is permanently mounted in my rooftop dome and is certainly not portable (the OTA alone weighs in at 30kgs)
Originally posted by GaryML Some of the older eyepieces have some really sharp optics, at the expense of eye relief and field of view. It seems like you are a bit of a collector, both camera gear and telescope gear.
Orthos are really made for high resolution planetary oberservations and the Zeiss ones excel at that, though I find the Pentax orthos at least as good, may be with a somewhat higher transmission due to the SMC coating.
Yes, I fear I have some kind of a hunter-gatherer gene... I have a lot of old Zeiss equipment, including the rare 150/900/2250 Cassegrain.
Originally posted by GaryML Funny you should mention the focus on the Moon, as I did had to refocus when moving from Saturn to the Moon. Maybe I didn't have the focus perfect on Saturn, as I can't believe that the telescope focus was different for these two objects. I thought it was odd at the time. I will explore this further.
Planets are hard to focus, as you don't have hard contrast edges. The view is more like somewhat fuzzy blobs and I always need some time to find the best focus for me. The moon on the other hand is so bright, that the pupil contracts and gives you more depth of field, thus making focusing hard. One problem with two different causes...
Originally posted by GaryML I didn't see the ad, but I read a comment in another thread here on PT that Pentax will make lenses for the Borg system. Rather a neat line of travel scopes. It's a pity that Pentax won't share their plans for their astro products, and we have to rely on rumors from the Internet and from store sales people.
You'll find the ad by Hutech on page 53 of the current S&T issue. They advertise the 125SD, which is made by Pentax. Whether it is the same optics as the Pentax 125SD I don't know, but I would expect that. As always, Pentax is very poor in marketing and communications.
Ben