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Old Nov 16, 2006, 5:59 AM   #11
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Hi Corpsy,

ISO is for the Internation Organisation for Standardization. ISO film speeds are supposed to be "standard" so all films will work with all cameras' exposure meters. With digital, this does not have to be the case, since the "film" is self-contained. IIRC, Canons are usually a little conservative with their ISO ratings, and I believe that they are usually a little more sensative than their ratings would have you believe. That being said, ISO speed should be pretty comparable between brands.

The reason that Pentax D and K1xx series cameras start at ISO 200 is that their Sony 6.2MP sensors have that as their "native" sensitivity. To get higher speeds, they amplify the signals coming from the sensor. The more you amplify the signal, the greater the variance between the signals from the individual photo sites, so the greater the "noise". You also degrade the image when you de-amplify the signal, so there is no sense to trying to standardize the ISO range (like making it 100-1600), as the lower ISO would actually give you a degraded image for the lower ISO which would be pretty counter-intuative in the photographic world.

A reason that noise might increase in proportion to shutter speed is that heat causes increased noise and heat builds up pretty quickly in a CCD.

I think that you would be well-served by reducing your expectations for any anti-shake system. Handholding a 1 second exposure is way outside the boundaries of realistic expectations for any such system. Think about it -- Assuming 1/focal length as being a reasonable guideline for sharp pics, and working backwards -- 3 stops faster will give you a shutter speed of 1/8 of a second. This means that the max FL lens that you should be able to hold for that 1 sec. shutter speed WITH SR would be 8mm (and considering the crop factor, 5.3mm). Anything longer (either in focal length or shutter speed) would be pushing the limits of the system. With a more realistic 16mm lens, the lowest shutter speed within the limits of the SR system would be @ 1/5 second (again considering the crop factor). Anything slower and your chance of a blurred image is increased significantly. YMMV of course, and good handholding technique will increase your odds, so some photographers will be able to do better than others, but to expect consistent good results from VERY slow shutter speeds is asking more of the technology than it can realistically be expected to supply. If you lower your ecpectations you should find yourself more satisfied with the performance of the system.

BTW, I own and still use both a Panny FZ1v2 and anFZ30 and plan to keep them (and the DS) even after getting a new K10D. Each of them will serve useful (though somewhat different) purposes for me.

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Old Nov 16, 2006, 11:49 AM   #12
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Corpsy wrote:
Russ, that second picture you posted is pretty cool, but I'm curious, why didn't you open up the aperture more?
Hmmm...good question. I guess because I'm still learning. Back in August, I had just gotten the K100D and was 6 weeks into using dSLRs. I just seemed to forget to use all the tools to my advantage.

Russ, do you have any examples of long exposures taken at lower ISO settings? One thing I found with my camera is that doing long exposures at increased ISO settings only seemed to multiply the noise levels, and so I always use ISO 80 or 100. I'm wondering if the K100d would perform noticeably better by using ISO 200 and opening up the aperture all the way.
The noise seems to be bad in this picture, but I didn't do anything to clean it up. I've taken others where the noise isn't bad, but to be honest, I don't take enough long exposures to worry about it that often. The included Pentax Photolab 3 software seems to do okay with noise reduction, if needed. Most people use Noise Ninja or other programs, though.
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Old Nov 16, 2006, 12:40 PM   #13
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Mtngal, thanks for posting those, that was really helpful. It gives me a a pretty good idea of what to expect, and the noise levels definitely look acceptable in those circumstances.

I'm really not planning on doing 1 second exposures very frequently, but often times with the FZ30 that was really the only option as upping the ISO setting produced unusable images. For darker, interior scenes, I'm thinking that pairing the K100D with a 50mm 1.4 lens might be a good way to get some shots that would otherwise be next to impossible with the FZ30 (my last trip to Howe Caverns comes to mind).

Scott, I guess what you're saying is that ISO 200 is probably a bit more sensitive than ISO 100 on a Canon, but not necessarily a dramatic difference. I'll have to look around and see if anyone did some testing.

Thanks for all the help!
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