Howdy. I have skywatcher 14" conical mirror with 2.6" secondary in a large DIY dob. I'm in the planning stages for rebuilding the dob (more lightweight) using "The Dobsonian Telescope" book by Kriege & Berry - it's an excellent book. Like many before me, I'm paining over what size my secondary mirror should be.
The 66mm (2.6") secondary I currently have gives a fully illuminate field for 12mm (0.5") diameter field size; the calcs from the book for a 20mm diameter field size result in the requirement for a 75mm (3") secondary. My question is: for purely visual observing using up to a 30mm eyepiece (68° AFOV), is there any significant practical benefit in using a 3" secondary vice a 2.6" secondary?? I've read plenty on the web and there are arguments either way & it can be quite confusing ... I'm interested in your experience(s). Thanks
Alex.