Zoom Wars — Optical v. Digital
I thought I might try an experiment today, and see if the “digital zoom” capability of the DiMAGE A2 was worth messing with. In theory, the 2X digital zoom would give me the equivalent of a 56-400mm lens. I figured the best way to do this would be to pop the camera on the tripod, make a shot with the digital zoom on, and then take the same picture with the digital zoom off. Then, once at home, I’d make two 8×10 prints — one using the full frame of the digitally zoomed image, and then I’d crop the “unzoomed” picture to match, and print that.
The first thing I noticed when I selected the digital zoom is that my camera sensor resolution was greatly reduced — from 3264×2448px (8MP) to 1600×1200 (~2MP). This didn’t look good, but, I figured I’d try the experiment anyway.
The results were less than stellar, and can be viewed below (I’m not sure how much you’ll be able to tell from these web images):
Here’s the image cropped from the full 8MP file.
This image is the full-frame 2MP digital-zoom image.
The digitally-zoomed image is quite inferior to the cropped image. We both saw it immediately in the 8×10 prints.
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By the way..I prefer the 8mp zoomed image…..it looks sharper.
Absolutely it is. The interesting thing is that they are both “two megapixel” images (25% of 8mp is 2mp, and the zoomed image is 25% of the frame). It must have something to do with the way Photoshop interpolates the image during the resizing.
You nailed it, G.
In-camera “digital zoom” is a hard-crop. A crop-and-resize in PS is a bicubic resample - a much more complex algorithm.