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Viewing the planets

Started by Larry Seguin, 10/06/2003 05:05PM
Posted 10/06/2003 05:05PM Opening Post
I'm hoping that some of you reading this have the experience to help me think through an issue. I've had a number of reflectors, and now own a 12.5" f/6 starsplitter with starsplitter optics. I've also had a number of 60 and 90 mm refractors, and currently own a C-102HD. I have an opportunity to upgrade this refractor to either a TV-102 or a Takahashi 102FS. Here's the questions: Does anyone have enough experience with these two scopes to know if one will significantly outperform the other for high power planetary viewing? And, does it make any difference? Would I be better off sticking with the reflector over either of the two apos? Thanks for any insights you can share. Larry Seguin.
Posted 10/06/2003 05:40PM #1
Well, a difficult question to be sure, Larry. I myself upgraded from my old C102-HD to my TV-102 and have no regrets whatsoever. To me, the TV-102 helped me enjoy the 4-inch aperture even more ;-). The TV-102 wiped out that annoying purple halo from the C102-HD (interestingly, it didn't bother me at first). It seems to snap into focus more so than the C102-HD (hard to describe until you see it). Daytime view of the varmints is crisper. The space between Saturn's ring and the planet's disc is black at high magnification instead of "haze looking" through the C102-HD. Finally, the blue festoon really looked well, blue ;-). The lowest contrast features become more clearly discerned (as well as those very tiny craterlets). Even M13 looked more sparkled and more resolved at 293x than I ever saw in my old C102-HD. The details I've been seening of Mars this year was very satisfying.

So first of all, I'd keep the 12.5" as that will be your "light bucket" ;-). However, as you know, the 12.5" f/6(!) is no small scope which is perhaps why you have the C102-HD for quick setup time or when you don't have time to setup the 12.5" and wait for it to cooldown.

Thus the question really boils down to: would you like to get closer to apochromatic properties, the better mechanics and the better optics of the TV-102/FS102 over your current achromat? If so, then you have a tough choice ahead ;-). If not, well do nothing maybe a good choice.

How high of a magnification can you achieve with either the TV-102 or Tak FS102 will be entirely dependent upon the seeing (and of course the aperture). Have a look at the link above to see how the TV-102 can do on the planets.

As to which one: the TV-102 or FS102, I don't think you would be sorry with either. There are some minor differences however. The fire-sale price of the FS102 is a better $$$$ deal, but the TV-102 OTA only comes with a hard case (I've been using it a lot lately ;-), it's lighter and shorter (after the dewshield is retracted) than the FS102, and you can get serviced here and can talk to Al/David Nagler about any problems. I'd say both focusers are buttery smooth but I somehow prefer the feel of the Tele Vue (maybe it's the rubberize knob thingy); also the Tele Vue focusing knobs have holes that you can get the Focus Lever for which worked like a charm in reducing vibration from touching the focuser at high magnification and also act as fine focuser. As you can see, it boils down to a personal preference ;-). BTW, to get the best from these APOs, you should feed it the best diagonals and eyepieces.

Good luck on your quest and let us know what decide.

Ron the 4-inch Tall Evangelist B[ee]
Posted 10/07/2003 05:35AM #2
If you wish something far more portable than your reflector, then a small Apo will be fine and certainly a good second scope. However, if you are just looking for a planetary scope, neither of these will outperform your reflector.

I own a 12.5 f/6 Starsplitter and my off axis mask, with no central obstruction, is about 4.8 inches (if I remember correctly). I haven't used it much, but the larger aperture of the off axis mask will provide better detail on the planets than any 4" scope. I find on nights of mediocre seeing, the full 12.5" is always better (larger image - more detail) than my 4" refractor.

So it really depends on what you really want.

Gary Weber

Posted 10/07/2003 06:35AM #3
>And, does it make any difference? Would I be better off sticking with the reflector over either of the two apos?

If you simply looking for the best planetary scope, a good 12.5 inch F6 Newtonian is in a different class than a 4 inch APO. IF portability is not a problem, then stick with the big one...