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Re: Focus problems on SP570UZ at full 20x zoom?

 
 
Mark Thomas
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      09-08-2008
DudeBoyz wrote:
> I'm having some issues when I try to use the camera at the full
> 20x zoom provided. They primarily seem to be related to
> auto-focusing. I'm not sure if the shots are coming out blurry
> when zoomed all the way in at 20x because of the Image
> Stabilization, the AF Illuminator, the flash or what


First up, almost every 'superzoom' has a compromised long end - the lens
won't be as sharp as at its 'sweet spot/s' and will probably have
reduced contrast. Are you viewing at 100%? Your expectations may be
too high.

Second, IS only gives you a bit of additional hand-holding ability. The
old rule of using a shutter speed of about 1 over the focal length (35mm
equiv) may only be helped by a stop or two. Check your exif - if you
are shooting at say 500mm with IS on, your shutter speed still needs to
be up around 1/250, imo, or you may encounter camera shake.

Motion blur/camera shake *looks* different to out of focus - why not
post a small crop (at 100% view) of the images and let us take a peek at
the problem?

Third - because your lens operates at a smaller aperture at the long end
the AF will be less reliable, especially in low light. And your AF
illuminator and flash will have a limited range (check manual).

 
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Mark Thomas
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      09-09-2008
DudeBoyz wrote:
> Thank you for the well thought out reply. I appreciate the tips.


Thanks for the appreciation!

> In most cases, zooming in all the way to 20x just isn't necessary
> for me, but I was trying to "torture test" the thing to find the
> limitations.


Better to find out about what your camera can do *before* you actually
need it, so keep it up!


> Is it possible that changing the metering type might aid in
> preventing the problem?


No. I can't see any way that changing your metering could help the AF
or lens sharpness! Tripod, yes. Lots of light, yes. Slow, smooth
half-press, yes. Backing off from the full >500mm focal length, yes... (O:

> I have left it at the default ESP, but
> there are two other modes. The "dot" mode means that the AF
> target mark area is metered, while the "dot-in-circle" mode
> meters a wider area.


(This may also help a little with your other question...) I had an
older model Olympus (C8080 - great camera!), and the ESP exposure thingy
worked well for most general purpose metering - I can't claim to be an
expert, but I got the impression it was a little like Nikon's matrix
metering (which is a good thing..). The dot (spot-metering) mode is
useful where you might have a background that will throw off the
exposure, while dot-in-circle (centre-weighted-average) is the 'common'
sort of metering (not as good as ESP, I found).

But, the *iESP* thing - which is for AF only - is a very different thing
and I hated it! Maybe they have improved it, but I found it made some
very strange focus decisions (seemingly to prefer the background over
almost anything else!) and I quickly changed over to the Spot focus
method, mostly using the old-fashioned-but-tried-and-true half-press method.

hth

mt
 
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