Adventures of a New Photographer: Nikkor 200-500mm f/4E Image Quality, continued

Testing the Lens

Nikkor 200-500mm f/5.6E

I went outside to my back yard a couple of weekends ago, at mid-day, and shot some sample images from my 200-500mm lens at different apertures and focal lengths. I had two goals:

Try to be more scientific about knowing my lens – which apertures provide the sharpest images at which focal lengths.
Try to mark the lens for focus at infinity at a known f-stop so I could photograph the upcoming Hunters Moon that night. (http://earthsky.org/astronomy-essentials/everything-you-need-to-know-hunters-moon).

I don’t have much that I can see or shoot a photograph of from my back yard that is very far away. I settled on a power transmission tower that is about 1,000 feet away. I’m not convinced that it is enough of a distance to make much of a determination from so I’ll have to re-do my tests with a better subject.

Considerations for Depth of Field

According to my DOF calculator, using 500mm at f/5.6, the far end of the focal range is 1,290 feet; I want to go to infinity for the distant sky photography. Even at f/8 the far end is only 1,450. I need something at about 3,300 feet to get the far end of the range out to infinity using f/5.6.

But, what I did shoot may tell me something about the lens performance at this shorter range… Okay, it really didn’t. When I pulled the images in to Lightroom I honestly couldn’t see much difference between any of the shots as far as sharpness is concerned. That means that either my eyes aren’t very good or all of the shots were equally crappy. I think it’s more of the latter.

I noticed that while I was zoomed out to 500mm that the tower was really jiggling in the viewfinder. I had my camera on my tripod sitting on my patio. I don’t get where the vibration was coming from. I took some of the shots at 1/500 second and some with 1/800. I didn’t notice what looked like motion blur in any of the images but they also didn’t look terribly sharp.

Adding weight to the rig

I tried some of the images after suspending a gallon of water from the tripod to see if that helped (a gallon of water weighs about 8 pounds). It didn’t make any improvement that I could detect.
Another thing I noticed is that there was atmospheric distortion. Without looking through the viewfinder I could see heat waves between my location and the tower. I could see that in some of the images too, where the arms of the tower were distorted.

The bottom line for my experiment is that none of my images looked terribly sharp. I hope to try again soon with a more distant subject in a colder location like Flagstaff, Arizona. I also want to try getting some sort of bean bag or something to place on the lens to try to dampen vibrations.

In the meantime, I've uploaded some of the images here. You can click on them to see the full size. These were exported from Lightroom with White Balance set to Daylight, Tone Curve set to Medium Contrast, Lightroom sharpening set to 50, Detail @ 50, and Masking @ 50. Lens corrections were enabled. Camera Calibration was using Camera Neutral v2. All other settings were zero, default, or off.

These images are at 480mm and 300mm, avoiding the limits at either end of the lens. They are at apertures of f/5.6, f/8, f/11, and f/16.