Pentax J80 f12, Antares 90mm f11, Orion 100ed f9?
Posted 22 June 2013 - 09:09 PM
I am making a bit of a reorientation and am adding some refractors to my scope stable. I currently use an 8" dob, but just bought the 90mm Antares, and am in a position to maybe get both of the other scopes (though maybe just one). The Pentax is more of a collectible purchase (in my view anyway - there is something about the idea of a classic Pentax refractor that is just neat). And the Orion is an attempt to get one of the best bang-for-the-buck apo's (not splitting hairs - I am sure it is close enough for my purposes).
I don't have much refractor viewing experience (which probably makes the idea if buying 3 seem odd), but there are a couple of opportunities that make it fairly reasonable.
I am mainly a planetary/lunar viewer - especially with these scopes. I am wondering if anyone has any comments about their relative performance, quirks, etc.
Posted 22 June 2013 - 10:59 PM
Posted 23 June 2013 - 11:16 AM
On the moon, the 80/11 had significantly more violet CA than my 70/6.2 William Optics Zenithstar with FPL-51, which is an "ED" and not a true APO.
I had an Orion 100/9 ED and it was much better than the William-Optics, particularly outside focus the Z70ED had a bothersome green halo.
So... 100ED >> Z70ED >> 80/11
I can't imagine the 90/11 would have better correction than an 80/11. The 80/12 would be better than my 80/11 but not by much.
So... the 100ED f/9 will blow away all of your other options, so long as you get a good one. But most of them are, due to the long slow focal ratio.
(oh, the reason I still have the Z70ED but not the 100ED is because.. the 100ED is really long, and has a substandard focuser. I replaced it with an AT90EDT 90/6.7 - which has superior color correction to the 100ED, as it's an FPL-53 triplet, but the main reason I got it was the 2.7" rack and pinion focuser, very useful for imaging)
Posted 23 June 2013 - 11:36 AM
The irony is that I probably did it in the worst possible order - I bought the Antares, should buy the Orion based on everyone's comments, yet still want the Pentax for the 'neat' factor. Given that I want the Pentax and need the Orion, the Antares(that I already own) is probably the least needed. LOL.
Good thing you can never have too many scopes...
Posted 23 June 2013 - 04:00 PM
AS80 has one advantage, it thermalizes very quickly. ED100 is fine too with that respect. Only with 30 degrees temperature drop, it still needs about 40-50 minutes to split theta Aur. AS80 is faster: this winter I could regularly make with it a sketch of Jupiter including GRS junior and be done in 20 minutes from taking the scope outside. I tried once Vixen 130ED but that was a fiasco. I started to see GRS in about 30-35 minutes, but clouds came in 40 minutes...
Posted 24 June 2013 - 08:01 AM
I did not see much difference in light-gathering capability, though I have been told that the effective aperture of the Antares is 96mm. Nevertheless, I don't think you will see much difference between the 90 and the 100. "Experts" may disagree.
I also did not see much difference in color between the two. Even when pushing ~400x on these 'scopes on the Moon there was just a micro-thin sliver of color around the limb. Contrast appeared to be very similar, with I think a slight nod to the Antares.
The big difference lay in their focal lengths, and the higher mags afforded by the Antares made double-splitting a lot easier. It also seemed to me that moments of steady seeing seemed "longer" in the Antares.
The 90 came out on top when it came to handling. Though the Meade is better built than the Antares and is a heavy little bugger, its shorter tube length made it easier to carry and mount.
Posted 24 June 2013 - 08:37 AM
Posted 26 June 2013 - 01:17 PM
Of course, the new-scope-curse is in full effect so I won't get a chance to observe through it for quite a while given our ever-present cloud cover.
Posted 03 July 2013 - 10:41 AM