It is unrecognizable as a cluster in larger scopes, but it really jumps out at you in smaller scopes.Compact apochromat with high-speed focal ratio: An ideal travel telescope for observation and astrophotography. This also works for star clusters like Collinder 70 in Orion's belt. Smaller scopes actually work better for larger extended objects like the North America Nebula because it compresses the object down to a recognizable scale. It is true that point sources will appear brighter in larger aperture scopes than in smaller ones at equal exit pupils. Resolution will suffer with smaller apertures, but not extended object brightness as it relates to exit pupil. At the same exit pupil, an extended object will have the same brightness regardless of aperture, just different sizes. Remember, extended object brightness is a function of exit pupil. I've thought about trading up to the AT72ED II with FPL-53 glass and the R&P focuser. Above that, there is some fringing on bright objects thanks to its FPL-51 glass. Otherwise, it's a great wide field scope good to 100x without false color. The Skywatcher focuser is generally considered worse yet. The Crayford-style focuser on my AT72ED slips under heavy loads as I point it close to zenith no matter how much I tighten the tension screw. If you plan to use heavy eyepieces or a binoviewer, get a rack & pinion focuser. Then maybe I will have a group of instruments to cover all bases and stop looking for that perfect scope. Now my plan is to get a smaller one and in the future, perhaps far distant, get a 120mm one, or around that. The urge to get a decent refractor, will not stop here either, my intention was to get a 100mm refractor, but considered that came too close to my C5 in performance. The Altair 80 ED-R is even lighter for instance. Of course there are plenty of other options too, which is not that much of a help really. I am also aware that the Skywatcher 80ED is a KG heavier than the TS one. I have even considered even smaller options, ( 60mm? ) having a certain nostalgia towards the memory of my first scope, that I still have, but have not used in ages. I also have a C5 and a C9.25 and to be honest prefer using the C5 as the contrast appears to be better. I am aware about the drop down in brightness and reach with the loss of aperture, but think I will cope with it. The gain in tightness of focus will make for some of the loss in sheer amount of light. One last thing, if you go from a 102mm scope to a 72mm scope, the reduced brightness and resolution might disappoint you, so if I were you i'd take the largest smaller scope. The TS scopes have a 2.5" rack-and pinion focuser that should slip less than the Crayford on the Sky-Watcher scope, and the larger drawtube will make for better illumination if you do imaging. I wish I could test all the telescopes myself but that's not possible □. Best of all, the rings inside the patterns have very nearly the same brightness, sharpness and color on both sides so none of that spherical aberration gremlin, the number one enemy of contrast. Overall an excellent lab test for the 72. There is a very small zone in the middle of the small defocus patterns but it's negligible, and the very faint violet and green outer rings are the extremely low level of residual chromatism that all apos have to some degree. The large defocus patterns have the same white color so no chromatic aberration to speak of. The sharp lines in the Ronchi pattern mean the lenses have an excellent polish, and the fact they are straight means there are no aberrations due to their shape. Everything I've read about the Sky-Watcher 72 is good but to make things less subjective here is a Ronchi and defocus test (made by Teleskop Spezialisten):
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