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Old Oct 18, 2010, 3:34 AM   #1
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Default Telezoom with OS dispite Pentax stabilised body ??

I'm considering buying a telezoom from Sigma , hesitating between the 120-400mm and 150-500mm

My question , considering that i have a Pentax body which is stabilised what is the point of buying a lens in it's stabilised version


I'm asking because in my local shop they have both versions of these lenses , the old not stabilised and the new OS versions , which cost 20% more.
Will the lens stabilisation give me better performance

Anyway , i'll probably use the lens most of the time with a monopod just to make sure of sharpness and i've heard that it is then adviced to switch the OS off .

Purpose for this telezoom is sport photography , cars , bikes .... and candid long range discreet photography
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Old Oct 18, 2010, 4:06 AM   #2
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generally speaking in lens stablisation is better at longer focal lengths so at 400-500mm you likely would be better with the OS lens - BUT it is marginal improvement so if the price difference is noticable then just get the non stablisaed version

as for when you have the lens on a tripod yeah you are supposed to switch of SR and OS as its a different kind of movement you get get and will likely jsut increase the blur not reduce it - a monopod is probably similar t a tripod but not sure - it migth help it might not

as for being discreet a 400-500mm lens is NOT discreet they are large and heavy lenses
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Old Oct 18, 2010, 5:57 AM   #3
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Quote:
Originally Posted by John.Pattullo View Post
generally speaking in lens stablisation is better at longer focal lengths so at 400-500mm you likely would be better with the OS lens - BUT it is marginal improvement so if the price difference is noticable then just get the non stablisaed version

as for when you have the lens on a tripod yeah you are supposed to switch of SR and OS as its a different kind of movement you get get and will likely jsut increase the blur not reduce it - a monopod is probably similar t a tripod but not sure - it migth help it might not

as for being discreet a 400-500mm lens is NOT discreet they are large and heavy lenses
But it will be discreet if i'm shooting from my livingroom, all i need is the reach
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Old Oct 19, 2010, 3:25 PM   #4
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I would think that at the shutter speeds you need for cars and bikes, that any type of stabilization wouldn't be very important. If you are panning you should turn off in-camera stabilization, don't know if that applies to in-lens stabilization also. If you are shooting from your house then you'll probably have the camera on a tripod, where there's no need for stabilization. So I don't see where it would matter. I'm also not completely convinced that the supposed "gain" you get with in-camera stabilization is worth 20% extra (yes, it would be nice to see a stabilized view through the viewfinder when using a 300+ lens).
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Old Oct 19, 2010, 6:14 PM   #5
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I can't remember exactly where I read this - possibly in a dpreview piece - but, with current technology, in-body image stabilization theoretically hits its limits at about 500mm. So, if you're leaning toward the 120-400mm, I don't think I'd bother with the OS at a 20 percent premium - even if it's a bit better than body-based IS. As for the 150-500, I can't imagine handholding that very often. So, again, OS might not matter. I think that's 2-and-a-half votes for passing on OS in this case.

Last edited by Biro; Oct 19, 2010 at 6:21 PM.
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Old Oct 20, 2010, 2:25 AM   #6
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Quote:
Originally Posted by Biro View Post
I can't remember exactly where I read this - possibly in a dpreview piece - but, with current technology, in-body image stabilization theoretically hits its limits at about 500mm. So, if you're leaning toward the 120-400mm, I don't think I'd bother with the OS at a 20 percent premium - even if it's a bit better than body-based IS. As for the 150-500, I can't imagine handholding that very often. So, again, OS might not matter. I think that's 2-and-a-half votes for passing on OS in this case.
Quite right
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Old Oct 20, 2010, 9:24 PM   #7
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I believe they are both right about not worrying about IS. If you want, take a look at my post of 'macro handholding a 6 pound lens' or something of that nature..

I shot those images with the tamron 300 sp 2.8 on an IST, no camera or lens stabilization and though I wouldnt reccomend it, due to the heft, the images came out rather sharp. I am getting used to not having Image stabilization while my K20d is in repair. This makes me doubt whether IS is really needed, especially if a tripod is used, and as others stated, you arent going to want to shoot a big lens like that handheld frequently as the trouble of hauling and mounting a tripod sure beats the pain of having to handhold the weight.
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Old Oct 21, 2010, 11:47 AM   #8
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It's my understanding that Amateur Photographer Magazine did a test in their January 21, 2010 issue comparing stabilization systems, including body based systems using models like the Pentax K7, Sony A550 and Olympus E-620

For the Pentax and Sony models, they included tests using the Sigma 50-200mm f/4-5.6 DC OS lens, to compare the effectiveness of body versus lens based stabilization with the same lens, measuring number of shots that were sharp at various shutter speeds, measuring the increase in resolution each stabilization system provided.

Apparently, the Sigma OS system in the 50-200mm f/4-5.6 DC OS performed better than Pentax SR (Shake Reduction), but it was beaten by the SSS (Super Steady Shot) system in the Sony A550. Here's a post in a thread about it:

http://forums.dpreview.com/forums/re...ssage=34339511

Of course, you may see different results with the longer Sigma lenses you're looking at (you'd probably need to take each camera body/lens combination on a case by case basis).

If you plan on shooting with tripod anyway (leaving stabilization turned off), then I'd try to figure out which lens has the best optical performance (as chances are, there are some differences between them in that area due to changes needed to allow for in lens stabilization). But, I don't know of a major review site that's tested all of them using the same cameras and methodology for comparison purposes.
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Old Oct 21, 2010, 12:35 PM   #9
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Quote:
Originally Posted by mtngal View Post
I would think that at the shutter speeds you need for cars and bikes, that any type of stabilization wouldn't be very important.
Well... a common technique used when panning with moving cars is to set your shutter speed much slower than you normally would, in order to enhance the feeling of motion.

Otherwise (with shutter speeds set too fast), you will freeze the wheels on the vehicles as well as the background. With slower shutter speeds, you can get blurrier wheels and background to enhance the feeling of movement (while keeping the vehicle sharper by carefully panning with it so that movement across the frame is minimized).

Quote:
If you are panning you should turn off in-camera stabilization, don't know if that applies to in-lens stabilization also.
I've seen it reported that Sigma's newer lenses with OS (Optical Stabilization) will automatically detect panning and only correct on the opposite axis. See the second paragraph on this Sigma lens review page at dpreview.com for one example. But, I don't know if that applies to all Sigma OS lenses or not:

http://www.dpreview.com/lensreviews/...p5-6p3_os_c16/

"...it also detects when the camera is panning and automatically switches to operating in one axis only..."

I've seen the same thing reported about Konica Minolta's body based stabilization (and Sony's body based SSS in their dSLR models should use the same technology, only improved with newer models). See the Anti Shake section on this Maxxum 7D review page:

http://www.dpreview.com/reviews/konicaminolta7d/

"...and can also detect a panning movement and only compensate for movement on the opposite axis..."

Nikon's in lens VR system does the same type of thing (automatically detects panning and only compensates for the opposite axis). If you go to this flash presentation about VR and click on the "Nikon Original VR Features" choice at the top of it, you'll see a Tab labeled "Panning" that explains their approach.

http://imaging.nikon.com/products/im...y/vr/index.htm

Tamron's VC lenses use a similar approach, allowing them to work while panning. For example, you'll find this in the description for some of their VC lenses:

"...With Tamron’s VC stabilizer panning is possible without annoying motion delay in your viewfinder and without having to change-over to a special mode..."

http://www.tamron.eu/en/lenses/overv...f-macro-2.html

Some (but not all) of Canon's IS lenses also allow for panning via a "Mode 2" switch selection on the lens. See this page about it:

http://www.usa.canon.com/content/Can...on/index5.html

I don't know how the Pentax SR system handles it.
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Old Oct 21, 2010, 9:38 PM   #10
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Interesting about being able to use anti-shake with panning. I don't know about the K7's owner manual, but previously the manual suggested that you not use SR when panning. I never remember to turn it off the few times I've tried panning and didn't notice any problem with leaving it on.

From your references, it sounds like having the OS in the sigma lens could then be very useful for motor sports - very good to know. In that case, I take back my comments about the OS gain being worth enough to cover the 20% extra. It very well might be the best solution - the OS gains during panning could potentially make up for a possible slightly less sharp optically lens. Sounds like time to go look at all those scientific lens reviews, then sharpen your budget pencil.
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