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Ordo Aug 11, 2009 12:48 PM

Lumix ZS3: how can I get a smaller aperture?
When I see exif from my new Lumix ZS3, 90% of the more than 2000 picks I shot in China are shot at an aperture of f4.0 or so. Even in Landscape Mode and midday sun the minimum aperture I get is about F5.0. Forget about f8 or f11 or f22, like I frequently use on roll films.
And in spite of the great Image Stabilization advances, I’m really disappointed with the sharpness I get and lack of depth of field.

Anyway to force a smaller aperture with this P&S? Thanks.

JimC Aug 11, 2009 1:20 PM

Your camera has a very tiny sensor. As a result, a much shorter focal length lens can be used for the same angle of view, as compared to the focal length needed on a 35mm camera with a much larger sensor size.

The actual focal range of your lens is 4.1 - 49.2mm (giving you the same angle of view you'd have using a 25-300mm lens on a 35mm camera).

As a result, you'll have *much* greater Depth of Field for a given aperture and subject framing compared to a 35mm camera. For example, on the wide end of that lens (actual focal length of 4.1mm), shooting at f/4, you could focus at around 3.5 feet and have everything from around 2 feet to infinity acceptably sharp at most viewing/print sizes.

That's one reason it's so hard to get acceptable background blur when shooting larger subjects so that they'll stand out from distracting backgrounds with that type of camera. You've got too much depth of field for a given subject framing and aperture because of the tiny sensor size and shorter focal length used for the same subject framing at a given focus distance. See this Depth of Field Calculator for more information:

Another reason your camera is limiting the smallest aperture to f/6.3 (and prefers to use wider apertures), is because of diffraction issues.

Because aperture (represented as f/stop) is a ratio between the focal length of the lens and the diameter of the aperture iris, and a camera with a small sensor uses a much shorter focal length lens for a given angle of view, the actual iris diameter can be very small. So, if you tried to use smaller aperture sizes (higher f/stop numbers), you'll start to get softer photos from diffraction by the time you're down to around f/5.6 at most focal lengths. Most cameras with smaller sensors like your Panasonic produce sharper images with the aperture left wide open (f/4 is going to be better than f/5.6 or f/6.3 at most focal lengths). See this article for more information on diffraction. If you use the calculator, your sensor size is going to be closest to the 1/2" choice (it's slightly smaller than that).

Ordo Aug 11, 2009 2:40 PM

Thanks JimC. I will have to study this issues to get the most of the camera. You know: this is a new medium for me.
In fact, I was dubious to get prints of the picks, even the best of them, cause I'm afraid to compare results with the big 50-60 cm. over detailed prints I get from my Mamiya 7. But after reading your post, I'll give them a try. LCD screens can be pretty untrustable. Thanks again.

Tullio Aug 12, 2009 10:46 AM

I don't believe there is any P&S out there with a lens that goes beyond f8.0. The reason is because an aperture of f8.0 on a P&S is equivalent to f32 on a DSLR. Now, when it gets to the wide open end of the aperture spectrum, things get much worse. For instance, an aperture of f2.8 is equivalent to f6.1 (or thereabouts). That means, not very good to create a nice blurred background (shallow DoF). Many P&S cameras try to select f4.0 as the ideal aperture because in 35mm terms, it's equivalent to f8.0, which happens to be one of the sharpest apertures of the entire range. The problem with the TZ7 is that it has no manual controls at all, thus you are at the mercy of Panasonic as far as aperture and shutter speed selections are concerned. That's why many people don't like cameras with AUTO mode only.

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