benefits of IS, help.....

i know there have been tons of thread about to IS or not to IS. but i have a question about IS.
i've heard people say that IS will give you 2 stops of IS, but what does that mean?
and ive heard how it will allow you to shoot 2 stops faster, and i dont quite understand that?

so i was wondering if u could explain this, thanks.

Each stop of IS equates to half of the shutter speed required to get a steady shot. Using the 1/focal length rule for a 300mm lens you would need a shutter speed of 1/300 (or 1/500 for a 1.6 crop camera) or faster to eliminate camera shake. With IS you simply divide the required shutter speed by 2 for each stop. So 2 stops gives you a shutter speed of 1/75. Here is a post from the Sigma 150-500 thread to show an example of how IS/Os helps.

In2Photos wrote in post #6043255
I have one more to share from last week to show off the OS on this lens.

I was shooting some birds at a local park when I saw this squirrel in the very dense shade next to a walking trail. The EXIF is as follows:

MKII, 500mm, no crop, OS mode 1, ISO 1600, f/6.3, 1/13s

That is about 5 2/3 stops! This image is a JPEG straight from the camera so it has had no PP, but I did play with it later and once I added a little contrast in cleaned up well. (click for full size)

HTTP response: NOT FOUND | MIME changed to 'image/gif'

When it says 2 stops lower, the shutter speed can be slower. However, the longer its open the more chance of it blurring due to the movement of your hand while holding the camera, this is where the IS kicks in it sort of counters the movement of the camera (not the subject) to keep the image steady. The more stops, the better the IS I think, but if you use a tripod then the OS isn't really necassary as the camera is always still anyway.
Theres my begginers explanation, hopefully it helps

2 stop IS will allow you to use 2 stops SLOWER shutter speed than without IS, and still be able to handhold the lens without handshake coming into play.

Let's pick the 70-200 f2.8 IS lens for instance. Assume we are shooting at 200mm

On a crop body, the rule-of-thumb shutter speed for handholding the lens would be.

1/(Focal Length x crop factor) = 1/(200 x 1.6) = 1/320

So 1/320 is the slowest speed you should be using to prevent handshake from causing blur...this is WITHOUT taking IS into consideration. YMMV.

Now enter the 3 stop IS system this lens has. This means you can use up to 3 stops SLOWER shutter speed than usual. So...

1/320 -> 1/160->1/80->1/40

So you can use 1/40 instead of 1/320, which may or may not be useful. It won't be useful when trying to stop subject motion b/c 1/40 is just too slow to do that. But it's great for shooting static subjects, indoors, etc...

mackidbrendan wrote in post #6043602
i know there have been tons of thread about to IS or not to IS. but i have a question about IS.
i've heard people say that IS will give you 2 stops of IS, but what does that mean?
and ive heard how it will allow you to shoot 2 stops faster, and i dont quite understand that?

so i was wondering if u could explain this, thanks.

In2Photos wrote in post #6043618
Each stop of IS equates to half of the shutter speed required to get a steady shot. Using the 1/focal length rule for a 300mm lens you would need a shutter speed of 1/300 (or 1/500 for a 1.6 crop camera) or faster to eliminate camera shake. With IS you simply divide the required shutter speed by 2 for each stop. So 2 stops gives you a shutter speed of 1/75. Here is a post from the Sigma 150-500 thread to show an example of how IS/Os helps.

ok i understand it now. so if one was buying a telephoto lens for outdoor daytime sports and would be able to always shoot over 1/500s (on a crop camera) would the IS then not be nesessary?

No...well, it's always nice to have the option that you can turn off as opposed to just never having it!

mackidbrendan wrote in post #6043679
ok i understand it now. so if one was buying a telephoto lens for outdoor daytime sports and would be able to always shoot over 1/500s (on a crop camera) would the IS then not be nesessary?

mackidbrendan wrote in post #6043679
ok i understand it now. so if one was buying a telephoto lens for outdoor daytime sports and would be able to always shoot over 1/500s (on a crop camera) would the IS then not be nesessary?

IS can still help as it will steady your image in the viewfinder. But I prefer to shoot sports without IS/OS as the lens can take a little time to steady the image and you might miss your shot. A monopod is usually more useful for sports than IS, IMO.

Are you sure sports are the only thing you'll end up shooting with this lens ? Once you have a telephoto you'd find ways to use it and many times you'd wish you had IS. It's not such a big price premium to pay for a very convenient feature.

One more thing to add regarding IS. It will stabilize your hand but not stabilize your subject. It allows you to get shots you would not get otherwise but if your subject is moving it will not prevent subject blur.

The 70-200 f4 IS lens have even 4 stops system.

nicksan wrote in post #6043687
No...well, it's always nice to have the option that you can turn off as opposed to just never having it!

ya for sure, as long as you can afford it

In2Photos wrote in post #6043698
IS can still help as it will steady your image in the viewfinder. But I prefer to shoot sports without IS/OS as the lens can take a little time to steady the image and you might miss your shot. A monopod is usually more useful for sports than IS, IMO.

ya thats what i have heard. and i would probably be using a monopod anyways. so the IS would not be necessary.

Amamba wrote in post #6043781
Are you sure sports are the only thing you'll end up shooting with this lens ? Once you have a telephoto you'd find ways to use it and many times you'd wish you had IS. It's not such a big price premium to pay for a very convenient feature.

well i was looking at the 300 2.8 but i cannot afford the IS version so i was looking at the non IS one. it probably wont be just for sports but i can afford the extra 1500$ for the IS

mackidbrendan wrote in post #6044204
well i was looking at the 300 2.8 but i cannot afford the IS version so i was looking at the non IS one. it probably wont be just for sports but i can afford the extra 1500$ for the IS

You might want to read this thread:
https://photography-on-the.net/forum/showthre​ad.php?t=543806

While the non-IS version has great IQ there is the possibility that if something happens to the lens it could not be fixed.

Isn't "stops" a silly term that makes almost no sense when applied to the effectiveness of IS ... almost.

Aperture settings are called f/ stops. They represent particular stopping points on the f/ curve. A change of one f/ stop doubles or halves the light reaching the film. Since doubling or halving the shutter speed has the same effect, then the word "stop" has been applied to shutter speed changes too. One stop faster is to double the speed, for instance.

Now IS enters the picture and allows you to shoot at a lower shutter speed, but how much lower? 3-4 Stops, of course .

My 70-200 f/4 IS is great for shooting sports. I shoot with IS off. For non moving subjects, I'll turn IS on and enjoy the expanded shutter speed range.

The kind of sports I shoot often involve panning, to follow the movement. Then IS mode 2 comes in handy, as it will still stabilize the vertical movement, but leave the panning alone.
The mode 2 setting is available on some lenses for manual selection, and some other will detect it automatically.