Canon Powershot model SX 20 IS, offers optical zoom up to 20X and digital zoom up to 4X thus offering a total zoom of 80X. Present zooming trial is carried up to 50X, in other words, 20x optical zoom and 2.5 X digital zoom; the same zooming lever actuating both optical/digital zoom functions.
Location: Bengali Association Durga Puja, Chembur, Mumbai on 21.10.2012. All the frames are shot from same location on hand-held camera.
Auto mode, Zoom 1 X optical (no zoom), 1.41 MB image, no flash
Auto mode, Zoom 1.2 X optical, 1.37 MB image, no flash
Auto mode, Zoom 1.4 X optical, 1.33 MB image, no flash
Auto mode, Zoom 2.4 X optical, 1.46 MB image, no flash
Auto mode, Zoom 2.8 optical, 1.51 MB image, no flash
Auto mode, Zoom 7.6 X optical, 1.81 MB image, no flash
Auto mode, Zoom 11 X optical, 1.75 MB image, no flash
Auto mode, Zoom 18.2 X optical, 1.54 Mb image, no flash
Auto mode, Zoom 20 X optical/ 1.5 X Digital = 30 X Total, 1.34 MB image, no flash
Auto mode, Zoom 20 X optical / 2.5 X Digital = 50X Total, 843 KB image, no flash.
Here the image has lost its clarity because the high total zoom magnifying the camera shake while trying to catch the image at the centre of the green AF (Auto Focus) frame. More often than not one gets an image not located centrally in AF frame, even though the shot may come out well. So multiple exposures of same subject is called for.
Auto mode, Zoom 20 X optical/ 2.5 X Digital = 50 X Total, 923 KB image, no flash.
Finally caught up with the image in LCD monitor inside green AF frame and managed to press the shutter to get a flawless picture! The image stabilization feature of camera minimizes the adverse effect of camera shake to some extent.
Observations: For this trial the pixel set in camera M2 (2592 x 1944) suitable for making A4 size prints. As per the manual the maximum total zoom recommended for this setting is 31 X which is much lower than our trial at 50 X. Conversely, as per manual if one wants to shoot at 50 X total zoom, he should set pixels at M3 (1600 x 1200) suitable for postcard size prints. If one aspires to shoot at 80 X total zoom the manual recommends pixels at S (640 x 480) suitable for sending email attachments. It may be taken note of that manual recommendations are for obtaining best possible photo clarity for a particular pixel setting without giving cognizance to other factors. The Frame 10 which lacks clarity due to camera shake will fail as a photo for any pixel setting.