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I think it is hard to compare the highend APOs for astrophotography.
Certainly there is a point where the difference is so hard to notice you would be better off with a larger aperture compound scope. Most astrographs are compound scopes.
APO imaging though has a wonderful appeal.
For sure the TOA 150 is right up there with the best. I find 99.2% strehl hard to believe especially when Tak do not make their own lenses. Also if you live in an area with rapidly falling temperatures the TOA150 may not be the best scope there as I wonder what the cooldown time is and whether the lens keeps up with rapidly falling temps with such a large air gap. Obviously in Sydney it works fine but then Sydney does not have rapid drops in temp really.
Marcus's images consistently show that bit extra resolution that you would not expect from 150mm aperture. Mike's AP152 consistently surprises with its resolution.
I myself tested my TEC180FL and AP140 on the same object with the same camera and the same location and there really wasn't anything in it except image scale and more detail as expected from the larger aperture.
Yuri has just posted he no longer makes the APO160ED as he can no longer get the glasses.
This has been a trend for AstroPhysics and TEC. AP no longer really makes anything besides 130's and Honders Riccardi and hopefully soon the Mak Cass. Roland can make 140s and 160s. Not sure what his plans are there but I don't think there have been anymore 160s made since 2005. I bet supply of the glass and its cost is the main bugbear plus the extra work of making an air spaced triplet versus an oilded triplet.
I think you would be looking a long time to get a scope better than the TEC160ED which is no longer made. Sure the 160fl would be better but would it even be noticeable? Maybe - hardly though.
Moot point now as it is no longer made. How long before TEC160 and 180 are no longer made. So its been 200Fl, 200ED and now 160ED no longer made due to inability to get the glass.
At this rate it could end up that TMB make the only large scopes from Russian glass.
I predicted this trend and was one reason why I stretched myself to get the TEC180 whilst they were still being made.
I bet a bunch of guys who've been around a long time kick themselves for not getting an AP155 or AP160 or AP180 when they were being made.
Greg.
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