Quote Originally Posted by peterborough_photography


The rhino picture was shot f3.5, 1/640s at iso 100 hand held.


I dont like the area at the bottom of the picture which is going out of focus, I have tried 3 of these lenses and they all do the same. Although not on every shot.


The foreground blur results from basic photographic optics - depth of field. Based on 200mm on a 50D and the size of a rhino, I'm guessing you're around 13 meters from them. At 200mm f/3.5 and 13 meters from subject, your DoF is about 0.5 meters. You've probably got 2 meters of grass in the foreground, which is going to be progressively more out of focus further from the subject. Stopping down to f/8 or f/11 will increase your DoF, but even at f/11 your DoF for the distances above would be under 2 meters, meaning you'd still have some foreground blur.


For many, the ability to blur the foreground and background with a wide aperture, which serves to isolate the subject and add impact to the picture, is one of the big reasons to use a dSLR. Going from a 1.6x crop like your 50D to a FF camera like the 5DII enhances that effect, since the crop factor also applies to aperture as it affects DoF. A point-and-shoot camera, with a much smaller sensor, cannot achieve the thin DoF you get with a dSLR. This is why dSLR landscape shooters use wide angle lenses and very narrow apertures (and tripods for the long exposure times which result from the very narrow apertures). But those long exposures are not so good for wildlife. If you really want to have the whole image in focus, crisp from close foreground to distant background, and still keep a reasonably fast shutter speed, one way to achieve that for this type of shot would be with a P&S camera.


I suspect most of us were having trouble seeing the 'flaw' in the rhino picture because that sort of subject isolation is a often considered a desirable effect. Imagine your zebra picture if the fence in the background was clearly in focus - personally, I would not want that.