Earlier, I asked whether people had first-hand experience with the digital zoom function, especially compared to non-DZ and just cropping the image. Well, I've done a quick comparison.
Approach:
1. take picture without dig. zoom (ISO 100, M-size, P-mode, 28mm, 1/180s, f2.8);
2. turn on dig. zoom (ISO 100, M-size, P-mode, 56mm (28mm x 2), 1/240s, f2.8);
3. cut identical scene from 1 (identical to zoomed in photo 2);
4. scale 3 to same size as 2;
5. compare 4 to 2.
- Used fixed camera position (tripod);
- Both photos taken as JPG (not RAW), M-size;
- Photos (1 & 2) taken within 10 seconds of each other;
- Photo 1 is slightly lighter due to 1/180s, compared to photo 2 (1/240s);
- Cutting and scaling of scene form photo 1 was done with Gimp 2.6 on Linux;
- For scaling I used two different algorithms: Cubic and Lanczos 3;
- Cut and scaled images were saved with 100% jpg quality.
Here are the photos (numbers referring to the numbers above):
1. without dig. zoom:
2. with dig. zoom (taken 10 seconds after 1):
4.1. cut from 1 and scaled using Cubic algorithm:
4.2 cut from 1 and scaled using Lanczos 3 algorithm:
M-cropped-50perc-scaled-up-(lanczos3) by
Robenroute, on Flickr
First impressions:
a. At normal viewing sizes, there's not much difference in sharpness between the cropped/scaled and dig. zoomed photo (although I do think the cropped version has slightly more detail to show (look at the flowers top left area)).
b. The Lanczos 3 algorithm seems to have retained slightly more detail (and sharper edges) than the Cubic algorithm.
I'd love to hear from you people what your impressions/opinions are (including feedback concerning the setup/approach/etc.). I know, the setup and approach won't qualify as scientific, and it's only a single picture/example. In addition, there's the fact that I've only looked at an M-sized photo (perhaps L-sized photos retain more detail; would be interesting to see how cropping would compare to dig. zoom).
Thanks & Regards,
Rob