I pulled up a note from many years ago when I owned a AP 6” f/12 Superplanetary. Over the years I kept notes as I compared scopes trying to find the “perfect planetary scope”.
12 October 2003
Last night and this morning I had it and the Meade 178 ED and the 6" AP side by side on Mars, the Trapezium, Saturn and Jupiter plus various double stars. 178 ED APO: All six stars clean and clear in the Trap with a 7mm UO ortho, split the double double at 88x cleanly (18mm Pentax SMC ortho) and provided the absolute best images of Saturn you could ever hope for. I kept going back and forth between the AP and Meade. My favorite view was the one I happened to be looking at. No kidding, the 178 was brighter (mentioned by another observer present) which made some of the detail on Mars easier to pick out. At 320x (5mm TMB) in the Meade I did notice a bit of color around Mars. Slight but there. None in the AP at similar power (6mm TMB Mono for 300x) hard as I tried to find it! And the Meade was right there in terms of sharpness and resolution as well. Both scopes were well cooled down and both were using AP MaxBright diagonals. Eyepieces were TMB monos, SMC Pentax orthos and UO orthos. The AP was on a G-11 and the 178 ED on a Parallax HD-150 on a pier (a bit too tall for the scope though it is the correct height for my D&G 8" F/12).
The last view of Saturn this morning was through the AP with a Denk I and a pair of TMB 10mm Monos. If that wasn't Encke's Minima then my mind has finally gone. And there were shadow-like fingers radiating outward in the "C" ring on both sides of the planet. Saw it first in the AP though it was then seen in both scopes (using same bino/10mm TMB setup) but a bit more so in the AP. Don't know what it was but quite noticeable.
I made a pretty detailed comparison:
TRAPEZIUM- Both scopes show all six stars. Interestingly, the 7mm UO ortho seems to make it easier to see them in either scope. I had tried a TMB 8mm in the AP and the UO in the ED APO. With this arrangement the ED was showing the fifth and sixth stars more easily. The brighter stars each had one clear diffraction ring. When I switched the eyepieces, the AP was just as easy as the ED. Go figure!
MARS: With TMB 8mm (225x) in the AP I can see a bright circular patch just above Syrtis Major. It almost looks like a cloud reflecting light. Once noticed, the spot was obvious in both scopes and I recalled seeing it first last evening in the Meade. Jumping to the Meade with a UO 7mm (230x) the image seems, if anything, a bit sharper. Must be the vagaries of the seeing conditions but it is a compliment to the Meade that it is running neck and neck in sharpness with the AP. I know from experience that there are a lot of folks who do not want to believe that the MeadeEDs can put up such a good image.
SATURN: I noticed that the stars are barely twinkling now (4:15 AM), looks like good planetary viewing. Through the Meade ED with a TMB 6mm mono (266x) Saturn is sharp as a tack and it's moons bright against a black background. Cassinis is a black gap all the way around. The globe has an olive-brown band just above the rings and an obvious coloration at the pole. The crepe ring is quite obvious as a "dusty" band against the globe. I imagine Enckes will jump out at any minute but so far nothing positive.
I popped in a Pentax XL 5.2mm ( 320x) and the image remained sharp and clear. The shadow of the globe is like an ink-line across the ring and I am just about seeing Enckes Minima- or imagining I am anyway! Nice image in the XL with a whole bunch of space around the planet.
Placing a pair of UO 12mm orthos into the Denk Saturn is brilliant against jet-black space. The moons are not quite so easy now though with effort all are still there. Don't seem to care as the 3-D effect makes me feel like I am in a spaceship approaching the ringed world. Razor sharp in moments of best seeing. Now a pair of TMB 10mm Monos are inserted- even better if that is possible-this may be the best view of Saturn I have ever had!
AP - Well I would not have believed it possible but the Denk/10mm TMBs in the AP are even better than in the Meade! Cannot tear myself away from the eyepieces even though I am sitting on the cold cement in order to view Saturn through this long scope at zenith. I swear I CAN see Enckes (Minima?). There is a dark line just in from the edge of the rings in moments of best seeing! And there is something else- it looks like dull shadows radiating out from the globe in the "B" ring. Initially I thought it was a shadow effect from the globe but it is on both sides of the planet. Not sure exactly what it is I am seeing but it sure is there to see. If the scopes were not starting to dew up I think it would still be out there!
FOCUSERS- Both can stand improvement. The Meade has an irregular "hump" as it is racked in and out. It creates a jump in the image much like mirror shift in an SCT. Disconcerting in a refractor but a Feathertouch or the like would fix it nicely.
The AP is an older version and has the 2" rack and pinion just like my old 6" D&G. Works but nothing to write home about. Biggest problem is the wimpy set screw intended to hold the diagonal in place. Extremely small and hard to reach with a 2" diagonal in place. I am hesitant to modify this scope as it is in mint condition and might appeal to an AP collector- assuming they can pry it away from me!
Verdict? Both are excellent planetary scopes. One could be quite happy with either for a long, long time. Now I am faced with the daunting task of deciding which to keep. Before the 178 ED came back from Meade I was pretty sure the AP was the "keeper." Now it is a lot harder to say. Guess I had better do a Meade/D&G shootout.