I just got the new Orion catalog which has the "apo" (which they state
is apochromatic) and the new digital dobs.

Interesting thing is that the 80 mm apo is 600 mm, f/7.5 while the ST-80
is 400 mm, f/5.0. But they state the max usable mags as 165x and 189x
respectively. Why would the ST-80 support higher magnification if they
both have 80 mm apertures?

Also, the ST-90 is on sale for the same price as the ST-80. So why
would anyone buy and ST-80? What am I missing here?

It will be interesting to see the 80 mm apo compared to the more
respected APOs we all have heard about.

Phil