The first optics I used to image deep sky astronomical targets was a fast Nikon telephotos at 200mm (f/2.8). To image the milky way I started with the Samyang wide lens at 14mm (f2/.8) that I replaced with the excellent AF-S NIKKOR 14-24mm f/2.8G ED. I was shooting with a stock un-modified Nikon D750 and the tracker was a Star Adventurer with a Manfrotto/Gitzo tripod. My very first tripod, the one I used to shoot my very first milky way images in Kefalonia island was a small Gorrilapod!
I am still using wide DSLR lenses, especially when I am travelling to dark skies. One of my most used DSLR lens is the Samyang 135mm f/2 which is very sharp.
Now, I am using various setups. All of them are using the legendary Takahashi EM-400 mount guided with the GT-40 guiding scope (using the PHD2 guding software) and Japanese refractors, Takahashi FC-60CB, FC-100DZ and FS-85EDP with their dedicated reducers and flatteners that lower their focal ratio considerably to allow me to capture more photons faster or just improve their image quality across the image field. When travelling, I am also using the iOptron CEM25EC that is very protable and has a precision optical encoder system.
My favourite DSLR is a 36.3-megapixel Japanese astronomical camera from Nikon, the D810A, that transmits light from the hydrogen-alpha spectral line at a rate that is four times higher than normal cameras, allowing me to capture faint details of nebulae that emit on that wavelength when I have access of a dark sky.
For narrowband and broadband imaging, I am using a Chinese astronomical CMOS camera from ZWO, the ASI 1600MM Pro Cooled Monochrome cooled down at -20C. With special astronomical 1.25' filters from Astrodon (USA) attached to a ZWO 8-position filter wheel, I can capture specific light wavelengths (Hydrogen-alpha, Oxygen III, Surlfur II, Luminance, RGB, Nitrogen II etc.) and combine them using variations of the Hubble palette.
Imaging with FSQ-85EDP and EM-400
My astronomical software of choice is PixInsight. I am using Photoshop as well. The capturing software I am using is SharpCap Pro.