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Old Jun 8, 2006, 9:31 PM   #11
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f2.8 is not necessary in good light, bright outside shots will have fringing almost all ways at f2.8shoot for a lower aperture and you will see the difference.

tight shots with f2.8 with zoom will offer a good dof very nice blurred background.

like this 1

sculpture by my brother....






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Old Jun 8, 2006, 9:36 PM   #12
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All cameras have fringing to some extent. So, get used to it. ;-)

Out of focus areas are going to be more likely to have it (because they're out of focus and blurry). ;-)

Image editors are starting to include features to help compensate for (PSP has features to help reduce it, and you can find tutorials and plugins for Photoshop to help, too).


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Old Jun 9, 2006, 1:26 AM   #13
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Nice picture of your Brother's sculpture, Willow. Did you use zoom? (I can't see the EXIF). Usually, the use of zoom creates great DOF. I haven't tried with the FZ20 but my experience with point-and-shoot digital cameras (as opposed to DSLR) is that DOF at WA is almost impossible to obtain. The reason is because an aperture of f2.8 is equivalent to f/5.6 on a DSLR, which means it's still not open enough. Actually, according to Peterson, in one of his books (Understanding Digital Photography if I'm not mistaken), he mentions that f4.0 - f/5.6 is the point-and-shoot lens "sweet spot" (equivalent to f/8.0 - f/11.0 in DSLR terms). These apertures produce the sharpest images.

Jim, I agree thatpurple fringingexists on just about any camera. However, some are worse than others and I do believe the FZ20 is much worse than the H1 or S2. I've takenover 1000 pictures with my H1 and very very few show some PF and even those are very acceptable.The PF on my bird shot is not acceptable to me.
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Old Jun 9, 2006, 1:15 PM   #14
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Tullio wrote:
Quote:
Nice picture of your Brother's sculpture, Willow. Did you use zoom? (I can't see the EXIF). Usually, the use of zoom creates great DOF. I haven't tried with the FZ20 but my experience with point-and-shoot digital cameras (as opposed to DSLR) is that DOF at WA is almost impossible to obtain. The reason is because an aperture of f2.8 is equivalent to f/5.6 on a DSLR, which means it's still not open enough. Actually, according to Peterson, in one of his books (Understanding Digital Photography if I'm not mistaken), he mentions that f4.0 - f/5.6 is the point-and-shoot lens "sweet spot" (equivalent to f/8.0 - f/11.0 in DSLR terms). These apertures produce the sharpest images.
Those numbers don't look right, unless you're comparing a non-DSLR model with a larger than average sensor, with a DSLR model that has a much smaller than average sensor.

Here is a handy online Depth of Field Calculator you may find useful:

http://www.dofmaster.com/dofjs.html

For example, the Panasonic DMC-FZ30 starts out an an actual focal length of 7.4mm at it's widest zoom setting, which gives it the same angle of view you'd have with a 35mm lens on a 35mm camera.

At f/2.8 using a focus distance of 5 feet, your total depth of field would be 6.03 feet

If you take a model like my Konica Minolta Maxxum 5D (or other models using the same size sensor like Nikon and Pentax DSLR models), you'd need to use a lens with a focal length of approxmately 23mm for the same angle of view (equivalent to 35mm on a 35mm model).

At the same focus distance of 5 feet, you'd need to stop down to more than f/8 to get the same total depth of field you'd have at f/2.8 with the FZ30 (it works out to around 5.72 at f/8 using a 23mm lens and focus distance of 5 feet with a KM 5D).

If you were using the Panasonic DMC-FZ20 (which has a smaller sensor compared to the DMC-FZ30), you'd need to shoot at around f/11 with a Konica Minolta, Nikon, or Pentax DSLR to get as much depth of field as the DMC-FZ20 would have at f/2.8

Now, if you compared a non-DSLR model with a larger sensor to the Olympus DSLR models, the numbers you mentioned may be closer to being accurate (since the Olympus models havesmaller sensors compared to DSLR models from Konica Minolta, Pentax, Nikon or Canon).

Of course, some DSLR models have sensors the size of 35mm film (Canon EOS-1Ds Mark II, Canon EOS-5D, some of the Kodak DSLR models), and those would have an even shallower depth of field for any given focus distance, aperture and focal length.

BTW, this statement is nottrue in most cases where you'd be more concerned about depth of field:

Quote:
..,the use of zoom creates great DOF.
It creates the illusion of a shallower depth of field. ;-)

As a result of their smaller sensors, the lenses on most digicams can have a much shorter actual focal length to get any given 35mmequivalentfocal length. Look at the front of your lens and you'll probably see the actual focal length printed (along with it's aperture ratings for the wide angle and full telephoto zoom positions).

So, your subject occupies a much larger percentage of the frame at any given actual focal length, compared to a 35mm camera at the same distance to subject with most non-DSLR digital cameras.

For any given 35mm Equivalent Focal Length, you'll have dramatically more Depth of Field compared to a camera with a DSLR or SLR with a larger sensor (or film) size. This isbecause Depth of Field is computed by the actual versus 35mm equivalent focal length,focus distance,and aperture, taking sensor/film size into consideration also for circle of confusion calculations.

Your ability to blur the background for any given aperture depends on your subject size, the percentage of the frame you need it to occupy (which you can use focal length or the distance to your subject to change), and the distance to the background that you want your subject to stand out from.

Of course, using the largest available aperture (represented by the smallest f/stop number) is often needed-- but this is usually not enough to achieve the desired results for larger subjects with most non-DSLR models.

Going for a tight head and shoulders (versus a full length shot) can help some (as can tricks like focusing in front of your subject). But, getting a shallow depth of field is very difficult for larger subject.

Keep in mind that when you use more optical zoom, you'll need to be further away from your subject for it to occupy the same percentage of the frame (hence, cancelling out thebenefits of longer focal lengths inmost shooting conditions where you'd want less Depth of Field). This changes as you shoot using settings where you get closer to the hyperfocal distance.

Using a longer focal length can still help, though. Theway the perspective changes (more compressed background caused byshooting fromfurther away) can give the illusion of a shallower depth of field, even if the real depth of field isn't changing, since you need to take the photo from further away if you use more optical zoom for the same framing.

Here is an article discussing the common misconception that using a longer focal length gives you a shallower depth of field:

http://www.luminous-landscape.com/tutorials/dof2.shtml


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Old Jun 10, 2006, 3:09 AM   #15
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Wow, that was one detailed reply, Jim. Thanks for all the info. you provided. I think I did not express myself very well with regards to DOF. As you mention, the FZ20 at f2.8 is equivalent to f11.0 on a DSLR. This means great DOF (no blurred background). That's exactly what I was trying to say. It is difficult to obtain a shallow DOF with point-and-shoot cameras because even at their widest aperture, it's still not wide enough to blur the background.
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