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Thread: I S

  1. #1

    Default I S

    Hi sorry, just wondering whats the difference between IS and Non IS lenes.
    ok stupid question but i'm considering getting a 70-200 L f4 lens but just can;'t make up my mind to get the IS or non IS version. the price difference is quite alot but just wondering how much does it affect the image quality.
    mostly using for travelling purposes will the non IS lens be affected by minor handshakes?
    If yes how much would it be affected?

  2. #2

    Default Re: I S

    imagine u want to shoot at 1/20 @ 200mm. will ur hand be able to keep still after u have been walking for hours? The IS allows you to do so. It detects that there is vibration and cancels it out when u trying to shoot at lower shutter speed. but note that IS does not freeze ur subject. so if ur subject moves faster than ur shutter speed... ur subject will still appear blurred.

    on top of that, the IS version actually is more dust and water resistant which is not in the non-IS version

  3. #3

    Default Re: I S

    mmm but how much more significant is the reduction in vibration...
    is it very significant?

  4. #4

    Default Re: I S

    impossible to say how significant unless you test it yourself, really.
    anw, IS is highly recommended. cos you never know when you will need it.
    and pls don get the wrong idea, i'm not trying to say you can't withstand long shutter speed handheld.

  5. #5

    Default Re: I S

    its roughly around 3-stops.

  6. #6

    Default Re: I S

    Never doubt IS. It can indeed help you by way of a few stops.

    "Stop" means the minimium shutter speed required by Non-IS for blur free, which is 1/(focal length x FLM) , divided by half. Many stops means many divison by two.

    For example, let's say you're shooting with a 50mm F/1.8 . Using the thumb of rule, u need minimium 1/50 shutter speed for a blur free picture but if let's say it's not possible(i.e low lighting) and you could only get less than that. It's where IS comes in. A 4 stop IS means u can technically shoot at 1/3(50/16 , 2power4 = 16) with the 50mm with guarentee(not 100% though) without having blur.

    Cheers
    Last edited by eosdigital; 8th October 2008 at 11:07 PM. Reason: paiseh, maths rusty liao lol
    Canon EOS 30D , EF 17-40mm F4L USM , EF-S 55-250mm F/4-5.6 IS

  7. #7

    Default Re: I S

    Quote Originally Posted by eosdigital View Post
    Never doubt IS. It can indeed help you by way of a few stops.

    "Stop" means the minimium shutter speed required by Non-IS for blur free, which is 1/(focal length x FLM) , divided by half. Many stops means many divison by two.

    For example, let's say you're shooting with a 50mm F/1.8 . Using the thumb of rule, u need minimium 1/50 shutter speed for a blur free picture but if let's say it's not possible(i.e low lighting) and you could only get less than that. It's where IS comes in. A 4 stop IS means u can technically shoot at 1/3(50/16 , 2power4 = 16) with the 50mm with guarentee(not 100% though) without having blur.

    Cheers
    Hi guys, sorry if anyone feels that I'm hijacking the thread.

    But is IS worth 3-4 stops for real? Say on a 55-250 Lens, at 250mm, is the IS really as good as at least 3 stops? 3 Stops is a huge amount, 8 times slower shutter...
    Looking for Canon 100mm F2 USM :)

  8. #8

    Default Re: I S

    Take and give abit. IS is more effectively to say abt 1 stop. 2 Stop theres chance to blur and 3 stop is chance to get sharp pic. 4 Stop is possible to get a decent pic. It works better on tele lens though.

  9. #9

    Default Re: I S

    Quote Originally Posted by ombre View Post
    Hi guys, sorry if anyone feels that I'm hijacking the thread.

    But is IS worth 3-4 stops for real? Say on a 55-250 Lens, at 250mm, is the IS really as good as at least 3 stops? 3 Stops is a huge amount, 8 times slower shutter...
    I would die without IS on my 55-250. Well, sort of.
    Meow!

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