In working with some long Canon telephotos recently, and now replicating the results with Nikon equipment, I now have a working theory that mirror lockup with remote release is not enough once past the ~300mm range: the shutter itself causes enough vibration to degrade image quality at lower shutter speeds.
Update! Reader Andrew Free sent a link to this page about Canon’s Live View electronic first curtain shutter. I’ll look into this with the 5D Mark II. —
I knew this to be true some years ago with ~800mm lenses using cameras like the Nikon D2x, but I was a bit surprised to see it at 400mm, especially given the care I take with mirror lockup and a remote release. This is something I’ll be investigating this month and documenting in my usual style, along with suggested mitigation strategies.
Multiple takes with both Canon and Nikon equipment need to be repeated to prove out the theory, and certainly an 800mm lens should demonstrate it definitively.
NOTE: my first post read TC-20E II and should have read TC-20E III, the new aspherical Nikon teleconverter.
Thanks to B&H Photo, I have the new Nikon TC-20E III aspherical 2x Teleconverter that I’m testing with the Nikon AF-S 200mm f/2 ED-IF VR, and also coming soon is the monster Canon 800mm f/5.6L IS USM bazooka (hey, it‘s only 9.9 pounds!).
Now if I can just get clear skies high in the Sierra next week, because a big challenge with long teles is getting clear air, not to mention distortion from air density differences.
Nikon TC-20E III — Mouse-over the actual pixels crop below taken at 1/40 second in order to see the 1/160 second result (same aperture, ISO 50 vs ISO 400). While there is some noise at ISO 400, the difference in sharpness is real.