This is the third in a series of posts on the effect of camera resolution on the quality of downsampled images. The series starts here.
In the first post in this series, I used Lightroom to process images of a Siemens Star, in an attempt to find out how well the superior image quality of a high resolution camera translated to images viewed on a 4k monitor. Now I will do a similar test with a real-world scene. As before, I used the Sony a7S and a7RIV. In this test the lens was the Sony/Zeiss 35 mm f/1.4 Distagon FE.
- 1/1600 second
- ISO 100
- Flexible spot
- Focus priority
- Medium spot size
- Three shots with each setup, with the best picked for this presentation
- Developed in Lightroom, PV 5
- Adobe Color profile
- White balanced to gray surround on target
- Sharpening set to: amount 30, radius 1, detail 0
- 4K downsampling done with the Lightroom export function, sharpening set to 0
Here’s the shot:
Tight crops from both cameras, at about 300% magnification for the a7RIV, and more for the a7S to keep the field of view the same.
As expected, the a7S image is a lot blurrier. Take a good look at the chroma aliasing on the masts and spars, though. That might get overlooked in prints, but when you compare it to the much cleaner a7RIV image, the difference is hard to miss.
Now we’ll look at some crops from the above image exported from Lightroom resized to 4K (because of the aspect ratio of the image, the vertical dimension was 2160 pixels, but the horizontal size was less than 3840 pixels).
Now the blurriness differences have all but disappeared, and all that remains is the a7S chroma aliasing and the aliasing in the diagonal lines of the a7RIV image.
Looking at another place on the same capture, first with crops from the full-resolution images:
As before, the blurriness difference is striking, and there is some chroma aliasing visible in the a7S image (though less than the first set of crops).
A close look at the 4K exports:
As before, the biggest differences are the chroma aliasing in the a7S image.
In the next post, I’ll look two other images. For those of you wanting to see what happens with other downsampling algorithms, be patient, I get to those.
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