I moved to mirrorless a few years ago, and agree wholeheartedly with John. I haven't missed my dSLR bodies since I sold them 2.5 years ago. Smaller, lighter weight, better auto focusing, seeing your exposure in the viewfinder, no need to micro adjust lenses for AF are just a few of the...
Now, for astro photography, that Tokina f/2.8 lens will be a useful tool. I don't really shoot that subject matter (not much opportunity where I live). However some of what John and I mentioned still applies. You will want to incorporate some foreground elements on land into the shot. Also, you...
I have owned a few ultra wide angle Canon zooms over the years -- EF-S 10-22mm (when I shot just a crop body), EF 17-40mm f/4 L and EF 16-35mm f/4 L IS. I probably used them more for interior or architectural shots than traditional outdoor landscapes. During my transition from dSLR to...
I do quite a bit of landscape photography. With that new ultra wide angle lens you bought, look for compositions with strong foreground elements for the best results. Personally, I don't shoot a lot of wide angle landscapes. My 24-105mm lens is plenty wide enough for most of my landscapes using...