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Old Mar 30, 2010, 6:40 AM   #21
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In the few large scale comparisons that have been done, Pentax performed slightly less well than the others. This is NOT a reason to select one brand over another. All implimentations of image stabilization performed much better than no stabilization. This is just splitting hairs, and while sensor shift IS applies the same system to all lenses, optical IS applies different systems to different lenses, some of which perform better than others, meaning that any brand specific judgements, one way or the other, are simply splitting hairs that have already been split.

In the December 2008 issue of Popular Photography, the article Image Stabilization Special: Stop the Shake appeared. In that article, the performance of multiple lenses from Canon and Nikon were compared with bodies from Olympus, Pentax and Sony. (Over time, Popular Photography cuts down on their server storage requirements by removing some of the charts and graphs, which has happened in this case, so the specifics are no longer available, not even on Archive.org's Wayback Machine, but your local library might have the print edition available if you want to check.) In that comparison, as I recall, the best performing optical IS was in the then new Nikon 18-200 VR-II, which gave a 4 stop advantage over no stabilization. (Other lenses didn't do as well.) Again, from memory, Sony's stabilization gave a 2 to 3 stop advantage, while Pentax' gave a 1-1/2 to 2-1/2 stop advantage.

Again, it's hair splitting.
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Old Mar 30, 2010, 9:03 AM   #22
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The VR II system used in the 18-200mm is very good. I was impressed with it when I had an opportunity to use one for a while.

Canon's got a new 100mm f/2.8 IS Macro lens out now with a redesigned IS System that appears to be as good as the VR II system in some Nikon lenses. It's effective to around 4 stops at typical shooting distances (dropping down to around 1 stop at closer focus distance).

Other lenses seem to vary some from lens tests I'm seeing, but on average, it looks like you can expect a high percentage of shots at about 2 stops slower than hand held for critically sharp images from most IS Lenses, with usable shots reaching out to as much as 3 stops (i.e., only mild blur, still acceptable for many viewing/print sizes).

The latest Pentax SR system tests I've seen (for example, the tests of the K7 by Amateur Photographer Magazine and the K-x review at dpreview.com), show it to be less effective than other stabilization systems (around 1 stop for critically sharp images, although usable images can still be had at slower shutter speeds).

My guess is that the new horizon leveling feature required a redesign impacting SR effectiveness with the newer Pentax models (but, that's only speculation as to why they don't test as well as other stabilization systems from recent tests I've seen).
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Old Mar 30, 2010, 9:44 AM   #23
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Quote:
Originally Posted by nymphetamine View Post
i had the Olympus E-520 for a while with the Bigma. It was 10 times lighter than canon and 500mm lens and with a mere addition of a flash i was enjoying the lightest 1000mm lens with IS.

I think Body IS is the way to go in the future. And i am sure lens IS will completement the Body IS in the future. May be a year or two down the line.

Olympus Body IS is good atleast for me
I'm contemplating an Oly next just for the same reason...

-> The lightest IS 500mm has to go to the Sony's however, one doesn't feel the extra weight of the lens in the back pack, and is only comparable in size to most 24-70 f/2.8
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Old Apr 13, 2010, 2:19 PM   #24
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@ JimC

i am really amazed to here you (Amateur Photographer Magazine) say that. I have an A200 and its God awful. i know thats pretty old now and might have come on a long way since then but i also have a Sony H5 bridge camera which was out way before the A200 but equally has much better IS.

i figured that maybe it was that you can't move an SLR sensor as easily as its like 40x the size.

Something that is maybe not for this tread but i haven't been able to find any info on. when people go on about 'fast glass' do they just mean the max F-stop the lens can do? Also i find people get all worked up about F1.5 over F2.8 saying it can let in 14 times more light or what ever it is but something that never gets talked about is the diameter of the glass. I know from telescopes and magnifying glasses (for burning) the size of the front collecting glass is massively important.

eg which is better F2.8 with filter size 58mm or F3.5 with 72mm?
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Old Apr 13, 2010, 2:32 PM   #25
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@ JimC

i am really amazed to here you (Amateur Photographer Magazine) say that. I have an A200 and its God awful.
Then, you're probably doing something wrong like using shutter speeds way too slow for the focal length you're shooting at (exceeding what you can expect from stabilization).

It should give you pretty good results at 2 stops slower than you can get sharp photos without it at a given focal length (and usable photos at most viewing/print sizes at even slower shutter speeds). See the tests at dpreview.com for an example of how well it performs.

http://www.dpreview.com/reviews/SonyDSLRA200/page15.asp

Or, you're confusing blur from subject movement with blur from camera shake (as stabilization won't help with blur from subject movement).

Quote:
Something that is maybe not for this tread but i haven't been able to find any info on. when people go on about 'fast glass' do they just mean the max F-stop the lens can do?
Yes. That's what people usually mean (since a wider available aperture allows for faster shutter speeds for a given lighting and ISO speed.

Quote:
eg which is better F2.8 with filter size 58mm or F3.5 with 72mm?
Better in what way? ;-)

The lower the f/stop number, the brighter the lens. f/2.8 is f/2.8 (or f/4 is f/4, etc.) for exposure purposes. For example, you should need the same shutter speed for proper exposure at a given lighting level and ISO speed at f/2.8, regardless of lens design.

You have to take focal length into consideration (as f/stop is just a ratio between the focal length of the lens and the diameter of the aperture iris opening). So, longer focal lengths will require more glass surface to allow for a given aperture (your f/stop setting).

The aperture scale in one stop increments (with larger than f/1 apertures possible but very rare in lenses) goes f/1.0, f/1.4, f/2.0, f/2.8, f/4.0, f/5.6, f/8.0, f/11, f/16, f/22... With each one stop move to a smaller aperture (represented by higher f/stop numbers), you will need shutter speeds twice as long for proper exposure for the same lighting and ISO speed (only half the light gets through compared to a one stop wider aperture).
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Old Apr 13, 2010, 2:40 PM   #26
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P.S.

Some users can hold a camera steadier than others, and some users may require even faster shutter speeds to reduce blur from camera shake. But, the "rule of thumb" for reducing blur from camera shake is to use shutter speeds of 1/focal length or faster (and you should use the 35mm equivalent focal length for that purpose). IOW, your shutter speed should be at least as fast as the reciprocal of the 35mm equivalent focal length.

For example, without stabilization or a tripod, you should be using shutter speeds of around 1/500 second with a 300mm lens (same angle of view you'd get using a 450mm lens) on a camera with an APS-C size sensor to reduce blur from camera shake (as blur from camera shake is magnified as focal lengths get longer), since the rule of thumb is to use shutter speeds of at least 1/450 second. So, with a stabilization system providing a 2 stop benefit, you should be able to get by with shutter speeds of around 1/125 second instead (4 times as long as the normal shutter speed requirements). But, stabilization won't help with blur from subject movement.
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Old Apr 13, 2010, 4:28 PM   #27
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Thanks JimC i really appriciate your time explaining that. I never realised the F-stop was linked to the lens diameter so i guess there never was a need to compare how diameter size increase the amount of light coming in.

i am guessing that there must be a difference from a really cheap f3.5 lens and high end f3.5 lens. eg thinkness and quality of glass etc.

anyway, the reason i have my doubts about the A200 is when i do a comparision from my H9 and my A200 keeping the iso, shutter speed and f-stop the same the A200 is always a lot more blurred. I couldn't tell you the shutter speed off hand, maybe 1/60th at 300mm f6.3 so again maybe i am asking too much of it but at the same time its strange how a much cheaper camera can perform so much better.
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Old Apr 13, 2010, 4:38 PM   #28
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How steady you can hold a given camera model also enters the equation. You may be able to hold the smaller and lighter camera steadier. Personally, I've found the opposite to be the case with dSLR models (but, each user is different). For, example, I find that a much heavier camera (think Nikon D3, etc.) is easier to get blur free shots from (probably because the extra weight makes it less likely I'll get vibration from depressing the shutter button).

Shutter button design and more also enters into the equation, as like a trigger on a firearm, some are going to be easier to press compared to others. So, if I'm shooting at very slow shutter speeds where blur from camera shake could be a problem, I'll try to half press the shutter button to get a focus lock, then smoothly press it the rest of the way down, waiting until the shutter opens and closes before releasing it to reduce any potential for vibration induced shake while the shutter is open.

Also, if shutter speeds are very slow, you could see some mirror slap induced vibration with a dSLR model (and you don't have that problem with a non-dSLR, as they don't have a traditional SLR shutter and mirror design). But, if you're shooting at shutter speeds that slow, you probably need a tripod anyway. ;-)
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Old Apr 13, 2010, 5:18 PM   #29
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yeah thats something i also hate about the A200, even on a tripod you still have to put up with mirror slapping as it doesn't have mirror lock up. not sure if you have used the A200 its a massive heavy clunck aswell!
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Old Apr 13, 2010, 5:23 PM   #30
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Personally, I think the A200 is a relatively light camera for a dSLR (try lugging around a larger pro grade camera for a while and see what you think) and it's mirror slap is really not bad in comparison to many others.

If you're shooting at shutter speeds slow enough to see a problem with mirror slap, then you're probably shooting a shutter speeds much slower than you can expect to get sharp hand held photos without a tripod, stabilization or not.
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