Spencer (our youngest son) and I carried the cameras and tripod to one of my favorite locations, the C&O Canal Historical Park. We had lovely, sunny weather to shoot across the Potomac and the many rocky bluffs and islands.
I continued to be impressed with the Nikon's speedy, no-fuss focusing. It's not critical in long landscape shots like these, but it's very nice. The Pentax displayed its typical sluggish-to-nonexistent autofocus behavior. I can't explain it but it's annoying, especially compared to the snappy Nikon. So it may be that some of the Pentax shots aren't perfectly focused. Exposures weren't exactly the same, either.
We attempted to adjust for the crop factor by shooting images on the Nikon at 1.5 times the focal length of the Pentax (recall that the D810 is full-frame and the Pentax, APS-C). We didn't hit that exactly, so I've adjusted the cropping in Photoshop to give approximately the same image sizes.
The results are impressive. The Nikon has outstanding resolution and the Sigma 24-105mm f/4 lens seems to make good use of it. Here are two uncropped shots, followed by two crops showing approximately the same area. Remember that these are all JPEGS with no sharpening added in Photoshop.
|Rocky Island (Nikon D810, Sigma 24-105mm f/4 at 75mm, f/8, 1/320 sec., ISO 400)|
|Rocky Island (Pentax K-5, Pentax 16-50 f/2.8 at 45mm, f/8, 1/125 sec., ISO 400)|
|Rocky Island (Nikon crop)|
|Rocky Island (Pentax crop)|
The overexposure in the Pentax crop unfortunately biases the eye against it, but you can easily see the difference in resolution...look at the trees, for example. Being able to crop that closely without going to mush would be very nice. The largest print you could make would be a lot bigger.
Some of you will say "Use primes! Zoom with your feet!" Fine, but in this location you would need to zoom with a boat. Prime lenses are sharp, low-cost and lightweight, but they don't always get you where you need to go.
One more thing I like about the Nikon: they have an app that lets you easily view manuals on your phone. It's well-designed and pretty easy to use. Nice touch.
Time to decide whether to add this expensive box to my kit. Very tempting.