[Decapod401]

While xBNSFer may complain about the screeners without having a single photo on RP, I have found most rejections that I receive expose technical errors that I have overlooked and it helps me to improve.

In this case, I doubt that shutter speed is an issue. Very few of the slides that I have posted on this site were taken with a shutter speed faster than 1/250, and your setting of 1/800 should be overkill for a 10 mph train. xBNSFer may be correct about just not being focused on the correct spot, but if not, I suggest that you take some test photos and see if the focus is consistently soft. You may have a lens calibration issue. I bought a relatively pricey 150-600mm lens for my D750, and I was unhappy with the results. After doing some research, I found that the focus points of the camera and the lens may not match and need to be calibrated. The lens came with a USB interface, and I bought a calibration pyramid and made some tweaks myself. It's a tedious process, and I would recommend surrendering your body and lens to a camera shop that will calibrate it for you. I moved to your area about a year ago, and was prepared to have someone do it if I was unsuccessful. Perfect Image Camera in Lancaster calibrates lenses, but I would call to make sure they can help