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10-18-2010, 12:30 AM   #1
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OS on Sigma telezooms

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

10-18-2010, 01:06 AM   #2
hcc
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QuoteOriginally posted by guillermovilas Quote
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
The lens OS is redundant with the camera SR (shake reduction).

There is an interesting article on in-camera image stabilisation vs lens OS:
Image Stabilization Test: Olympus E-520 SLR Body - SLRgear.com!

The outcome: "The bottom line on the [camera]'s IS system is that it turned in a superb performance, very much on par with the best lens-based IS systems we've looked "

In your case, your camera has already IS (the SR system); you do not need an OS-lens and you would better off by getting the non-OS lens if the optics is identical to the OS-lens.

Last edited by hcc; 10-18-2010 at 06:10 PM.
10-18-2010, 02:53 AM   #3
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QuoteOriginally posted by guillermovilas Quote

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 .
I stand to be corrected on this, but I understand it's ok to leave IS on when using a monopod; off on a tripod
10-18-2010, 03:08 AM   #4
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Hi,
IMHO main difference betweeen SR and OS - speed. You have to wait a little for SR (half press shutter), but OS is efficient all the time. If you shoot action, OS might have some advantage (I mean not to miss a shot while waiting for SR on).

Regards,
A.

10-18-2010, 04:27 AM   #5
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Also, depends on which body you use. The Sigma OS may give you a stop or 2 more then the SR. Newer bodies probably not as much.
10-18-2010, 05:23 AM   #6
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If you're doing manual focus for any reason, then the in-lens os will also stabilise the image in the viewfinder, making it easier to nail the focus.
10-18-2010, 11:37 AM   #7
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In one of the other threads on the subject, posted that I like to use the in-body SR so I can see how steady I can get first. If the image is stabilized in the lens, you won't know how good you are.

Also, you'll need to get in the habit of switching off the OS if you change lenses as there is a warning about possible lens damage otherwise.

And, if you like accurate exif data, OS will not show in the SR field, much like off-camera flash during a long exposure.

But, I use a monopod with mine.

And the lens in in fact silent when focusing, which takes some getting used to after all this time with screw-drive...
10-21-2010, 02:23 PM   #8
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Well after testing both Sigmas 120-400mm and 150-500mm in my local shop , i found that both lenses produced equivalent optical results , neither lens producing sharper pictures no better AF one over the other and this handheld with body stalilisation.

What made me choose the 120-400m is ergonomics , it is better in hand , better balanced and the zooming ring was smoother and easier to manipulate .

Allthough i would have liked the extra 100mm reach , the 120-400mm really was the better choice for me , it`s big but still not too big,no problem using it handheld , the 150-500mm really felt too massive.

10-21-2010, 05:06 PM   #9
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QuoteOriginally posted by guillermovilas Quote
Well after testing both Sigmas 120-400mm and 150-500mm in my local shop , i found that both lenses produced equivalent optical results , neither lens producing sharper pictures no better AF one over the other and this handheld with body stalilisation.

What made me choose the 120-400m is ergonomics , it is better in hand , better balanced and the zooming ring was smoother and easier to manipulate .

Allthough i would have liked the extra 100mm reach , the 120-400mm really was the better choice for me , it`s big but still not too big,no problem using it handheld , the 150-500mm really felt too massive.
Well done. The hand test in the store is the best test that you can do. Congratulations for your choice and happy shooting.
10-21-2010, 11:51 PM   #10
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QuoteOriginally posted by hcc Quote
Well done. The hand test in the store is the best test that you can do. Congratulations for your choice and happy shooting.
Yes you are right , the more you read posts the more you get confused sharpness issues are not consistent , everyone tends to defend he's own choice but how many actually had the possibility to try them both out side by side and check the results on a big 27' screen.

I did for an hour and could see the real end result and choose which is best for my purpose
10-25-2010, 06:20 AM   #11
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anyone know if a tamron 70-200 updated lens is in the wind ?...how often to Tamron update their line up
10-25-2010, 08:35 AM   #12
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QuoteOriginally posted by hcc Quote
The lens OS is redundant with the camera SR (shake reduction).

There is an interesting article on in-camera image stabilisation vs lens OS:
Image Stabilization Test: Olympus E-520 SLR Body - SLRgear.com!

The outcome: "The bottom line on the [camera]'s IS system is that it turned in a superb performance, very much on par with the best lens-based IS systems we've looked "

In your case, your camera has already IS (the SR system); you do not need an OS-lens and you would better off by getting the non-OS lens if the optics is identical to the OS-lens.
The linked test/comparison is irrelevant to the subject, unless you can find a good side-to-side test of Pentax SR vs. Olympus in-body stabilization. (I'm not sure if this is possible due to the differing crop factors, which may in fact affect the relative benefit of in-body stabilization vs. lens-based stabilization.)

The general rule of thumb I've seen is:
In-body stabilization tends to do better for shorter focal lengths. Lens-based IS tends to do better for longer focal lengths. Even the article you linked comments on this aspect - "was about as good as that of one of the best lens-based IS systems we've tested, namely that of the Canon 70-200mm F/4L IS. And at shorter focal lengths, it did better."

The OP is looking at lenses with significantly longer focal lengths than tested. (400-500mm actual focal length - longer than even the EFL of the lenses tested.)

Also keep in mind that in-lens stabilization is not just about stabilizing your shot - lens-based IS stabilizes your viewfinder image, making it easier to frame the shot AND making the autofocus system's job much easier. I have a Sigma 18-250 with OS - the OS really helps with focusing.

On the other hand - I don't know about the 150-500, but for the original 50-500 - the non-OS Bigma was EX grade glass, while the BigmOS is NOT EX-grade glass and numerous reviews say that there is a clear image quality difference (not just a naming/designation difference.)
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