First, welcome to Cloudy Nights...Cloudystars.
Larger aperture achromats, I find, do indeed make for excellent deep sky scopes.
There are several brands of well made 6" F6-ish achromats that will serve well. And even more of the 6" F8 versions which have been out for decades, readily available on the used market, and bargains in the refractor world at ~$400 USD used. They make excellent deep sky scopes and I consider them light weight for their apertures. Eyepieces also "like" the slower focal ratio too.
So you can hunt one down (won't take long) and try it out to see if that is the type of thing you want. If you shop carefully, you can resell it for what you paid too. AND...they can also be easily cut back for bino-viewer use if you have some simple hand tool skills.
Yes, Istar does make some excellent lenses and if you, again, have some skill with hand tools, you can roll your own tube assembly around the lens. I've done so many times as I just like it. But, for the money the common 6" F8 is a great deal, especially used IMO.
Now stepping past the 6" aperture really ramps up the size and weight of the OTA quickly (roughly the cube of the aperture ratio), but also that of the mounting....and the cost too But it can be done with careful design. Attached is an 8" F9 scope I made that came in under 30 pounds for the bare OTA. It had an OK lens that I dug up on the net but was indeed spectacular on DSO's art low to moderate magnifications and my Losmandy G11 could actually swing it around quite well, especially at low power.
Edited by Jeff B, 08 November 2019 - 09:17 AM.