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Old Jan 2, 2005, 10:48 PM   #1
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Hi. I have had my KMZ1 for about 9 months. Apart from close-up photos taken with the10x optical zoom, I find the picture quality is poor because it has only one focusing point. Edges are out of focus. eg If I take a photo of five people, the ones on the outside are out of focus. I had accepted this as a penalty for having the x 10 zoom, (well you cant have everything). then I bought my son an entry level Kodak digital recently and the general photos he is taking are better than mine at 1/3 the price! The Kodak has most of the photo in focus with a wonderful depth of field. My photos are darker as well. We have spent the last day making comparisons with the same subject material at the same time.Also page 37 of the manual "Shooting tips" says "the larger the aperture value, the greater the depth of field." I thought it was the other way around. I have read the manual from cover to cover and cant see how I can improve my photos from the Z1, in fact "sports" mode gives the best focus. Are there any cameras around that have a 10x optical and more than one focusing point? cheers Ros
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Old Jan 3, 2005, 10:56 AM   #2
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Aperture questions can be a little confusing because a larger NUMBER (f/11 compared to f/5.6) means a smaller OPENING. Keep in mind that the aperture number is actually a ratio (of opening to focal length), and if you divide by something bigger you get a smaller result. The manual could have been more clear about that.

As for the problem you're having, most P&S cameras have a relatively small aperture and this is why you don't have to focus them--the depth of field with an aperture that small covers distances from a few feet to infinity. The Z1 has a maximum aperture size between f/2.8 and f/3.5, depending on your focal length setting, so depth of field won't always be as great as with a f/5.6 P&Swith the same focal length.

The distance from your camera to the group of people might play a part, too--if you're fairly close, the person or people near the middle of the photo can be a foot or so closer than the people at the edges of the photo, which would possibly put them out of focus. Try moving back a bit and zooming in--the people at the edge of the photo will be proportionally not so much farther away. I'm not sure at what point the smaller depth of field from a longer focal length would offset the smaller proportional difference in distance from subjects to lens, though.

Any camera will have only one "focusing point." There is no way to make a lens focus at two discrete distances at the same time, but you can improve the depth of field by changing the aperture and/or focal length settings.
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Old Jan 3, 2005, 11:11 AM   #3
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Depth of Field is dependent on aperture, focus distance and focal length. The smaller your aperture setting (represented bylarger f/stop numbers), and the greater your focus distance, and the shorter your focal length (amount of zoom used), the greater your depth of field.

It's very unlikely that the Kodak has more depth of field than your Z1 (given the same settings). This is because the sensor in your Z1 is very small, letting it use a much shorter focal length lens for any given 35mm equivalent focal length compared to many models.

The more likely reason you saw a difference is because you were focusing on a closer subject (and/or filling the frame more using zoom) compared to the photo taken with the Kodak. But, as Tom mentioned, the Kodak may be using a smaller aperture by default.

To get a better idea of how Depth of Field works, use this online depth of field calculator. Select your camera model, making sure to use the actual (versus 35mm equivalent) focal length of the lens for calculations (5.8 - 58mm with your Z1).


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Old Jan 8, 2005, 1:56 AM   #4
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Thanks folks for your informative replies. I would like to attach a photo to show you what I mean, but I failed. Any hints? I am using the Minolta on "sport" all the time and getting better results. I will be away for a month, so will follow up when I get back. thanks again. I understand about depth of field but not the operation of P&S cameras. cheers ros
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