When driving around, I always took a Nikon D700 with a 24-120mm VR Nikkor and a 500mm Nikkor Mirror lens inside a very padded Pelican case. The 500mm I used less than 5% of the time, but got some great shots with it. Last year came across a 600mm f/8 Vivitar Series 1 SOLID CATADIOPTRIC lens and an 800mm f/11 Vivitar Series 1 SOLID CATADIOPTRIC lens in NOS condition for a price that was too tempting to pass over on. To my surprise both optics are amazingly sharp. Coupled with a Nikon Z6 with its in camera VR and its Focus Peaking option (Custom Setting D10) the combination is amazingly easy to use. Also machined a bracket that allowed both the lens and the camera body to be attached to it, and intern the bracket to be either placed on a beanbag or mounted on a tripod head, and problems with vibrations from using slower speeds disappeared. The 800mm SOLID CAT is just as sharp as my 800mm f/5.6 MF ED-Nikkor at f/11. Yes the out of focus background differs but not all the time. Now always carry around a Nikon Z6 with a 24-200mm Z f/4-6.3 VR Nikkor and the 800mm Vivitar SOLID CAT in that Pelican case. I have been using the 800mm CAT many times over the 500mm Mirror lens.
