Autofocus Issues?

I added a Nikon D500 to my collection recently and initially I was very happy with it, but as I started reviewing images I became concerned. Many of the images, while focused, did not seem very sharp. They lacked the detail I was used to seeing on my D750 with the same lenses. I initially thought that the image preview on the screen was low quality, making things look soft when they actually weren’t, but I saw the same softness when viewing on my Mac. I next thought my lenses weren’t calibrated to the autofocus system so I used AF Fine Tune to calibrate across different lenses, but it didn’t make much of a difference. It was frustrating because some images were sharp and detailed while others weren’t. I even verified that the image was focused under the selected focus point by reviewing images in Nikon’s software.

I cleaned the autofocus sensor and that seemed to improve accuracy but I still had random images that weren’t detailed. I considered how I was evaluating the camera and realized I wasn’t shooting the way I did on my D750. I was using continuous autofocus and shooting everything in high-speed continuous (10 fps) mode . I usually use single autofocus on my D750 and high-speed continuous mode which tops out at 6.5 fps. Continuous autofocus prioritizes taking a picture over having a perfectly focused one and cameras with very high speed mechanical frame rates have a tendency to add additional vibration to the image. Since I was taking photos with long lenses on a magnified sensor at high speed, I think I was introducing vibration and motion that resulted in soft images.

I decided to practice better technique at the beach a couple weeks ago and I got many shots of seagulls in motion with sharp eyes. I also brought my D750, D500, and D3200 to one of Zach’s soccer practices with one of my sharpest lenses. I swapped that lens between each camera to take photos of Zach in motion as well as stationary objects around me. After reviewing the results I could saw no major differences in sharpness across the three cameras, except that in some cases the D500 was the sharpest. I even took some photos with my macro lens, all using autofocus, and they came out great – sharp and detailed.

This series of tests felt like enough for me but I still had a concern in the back of my mind. Why weren’t the images as detailed as the ones from my D750? It was a smaller sensor, but resolution was close. Why did my amazing lenses not result in amazing photos? I didn’t want to buy a camera thinking that it might not work the way it is supposed to. I also didn’t want to turn around and spend another $200 to send it to Nikon for calibration. After reviewing more images from D500’s online and not being satisfied with my own, I decided I needed to try another copy. B&H didn’t have any more used models in stock so I couldn’t exchange it. Time was running out and I really needed to make a decision – return it because I had reservations or keep it and risk having buyer’s remorse.

I found a compromise: buy another used D500 from someone else and compare. I’d keep the sharpest one and return the other. So I did. I bought another D500 from MPB in similar condition. I brought both of my D500s around with me, shooting the same or similar scenes on each with the same lens. If my original D500 had focus problems, this new D500 would be instantly better.

It wasn’t. Overall I saw the similar image quality from the second D500. Shadow detail was a bit muddy and wasn’t as good as my D750. The number of in-focus shots felt about the same between the D500s and in general the area under the focus point was what was in focus. I got those great seagull photos from my first D500 and some good general shots out of the second one. So what does that mean?

I’m simply being too hard on the D500. It’s unfair to compare it to my full-frame D750 because a full frame sensor will always resolve more detail than a crop sensor, especially at slightly higher resolution. I’m just not going to get a razor sharp bird when it’s far in the distance taking up only 5% of the frame. I also was looking at images of the boys’ faces, often in shadow, wondering where the detail was. A crop-sensor just needs a bit more light to make those details come out. That requires higher ISOs which are noisier than my D750.

After lots of testing, lots of research, and the purchase of another camera I finally feel comfortable that my D500 doesn’t have any major focus issues. Did I find some improvements when trying micro adjustments? Sure, but they weren’t huge and didn’t magically add detail to shadowy images. In summary, I was being over-sensitive, expecting too much from the sensor, and not using good technique with fast continuous shooting speeds and long focal lengths.

Despite the anxiety, I learned a lot of technique from this experience, and despite taking a lot of junky test shots, I also ended up with some really great images as well. My second camera has been returned to MPB and I feel confident that my purchase of a D500 was a good one.

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