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Thread: auto focus points + image stabilizer inquiries

  1. #21
    Moderator Octarine's Avatar
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    Default Re: auto focus points + image stabilizer inquiries

    Quote Originally Posted by dingaroo View Post
    Talking about handholding technique, do you find it irritating when people are using the dSLR and hold it like a P&S?
    To each his own. It looks silly, indeed. But I find it more irritating when somebody asks me to help taking a picture with a flimsy PnS where I don't know how to hold properly, let alone operate these tiny buttons. But it's funny to see: the cam has recognized 4 'eggs' in a group of 6 people
    EOS

  2. #22

    Default Re: auto focus points + image stabilizer inquiries

    Quote Originally Posted by Octarine View Post
    Why do you think you need lenses with IS? There are many good lenses available without any IS, be it Canon or 3rd party lenses for Canon mount. Even Canon L lenses (professional grade lenses) of shorter focal length don't have IS. Reason: for shorter focal length (up to 50..70mm) there is no real need, it's easy to handhold. General rule of thumb: shutter speed should be faster or equal to "1 / focal length". For the kit lens it means: faster or equal 1/50s at its longest end. Pretty easy to achieve in daylight, also considering the low weight of the lens.
    For longer lenses there are also affordable models with IS in Canon line-up, e.g. EF-S 55-250mm f4-5.6 IS.
    hi bro. pardon me for my ignorant. can you pls explain in simple layman terms or give an example on your comments "General rule of thumb: shutter speed should be faster or equal to "1 / focal length". For the kit lens it means: faster or equal 1/50s at its longest end"

    thanks in advance

  3. #23

    Default Re: auto focus points + image stabilizer inquiries

    E.g your lens is 18-55mm, to get a stable shot, your shutter speed must be (1/focal length)s. Meaning if you are zoom in at 55mm, you need at least 1/50s of shutter speed to avoid blur pic. There is no such shutter speed of 1/55s so it's either 1/50s or 1/60s if you wanna be safe.

  4. #24
    Moderator Octarine's Avatar
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    Default Re: auto focus points + image stabilizer inquiries

    Quote Originally Posted by rockdhop View Post
    hi bro. pardon me for my ignorant. can you pls explain in simple layman terms or give an example on your comments "General rule of thumb: shutter speed should be faster or equal to "1 / focal length". For the kit lens it means: faster or equal 1/50s at its longest end"
    There is a point when laymen terms become imprecise and misleading. Since you venture into photography I strongly suggest that you make yourself familiar with the very basic photographic terms. Shutter speed and focal length are among them. Without it's nearly impossible to explain things, unless we start using things like "that numbers there on the round cylinder poking out in from your cam.. yeah, the one you point to your gf face"...
    Read the Photographic notes for newbies as first reference. See what the shutter does, then the term 'shutter speed' becomes clear. Focal length is the most important parameter of the lens and defines what you see in the picture. The rest is basic Maths.
    EOS

  5. #25

    Default Re: auto focus points + image stabilizer inquiries

    Quote Originally Posted by tecnica View Post
    E.g your lens is 18-55mm, to get a stable shot, your shutter speed must be (1/focal length)s. Meaning if you are zoom in at 55mm, you need at least 1/50s of shutter speed to avoid blur pic. There is no such shutter speed of 1/55s so it's either 1/50s or 1/60s if you wanna be safe.
    thanks bro. thanks for the clarification. truly appreciate it.

  6. #26

    Default Re: auto focus points + image stabilizer inquiries

    Quote Originally Posted by Octarine View Post
    There is a point when laymen terms become imprecise and misleading. Since you venture into photography I strongly suggest that you make yourself familiar with the very basic photographic terms. Shutter speed and focal length are among them. Without it's nearly impossible to explain things, unless we start using things like "that numbers there on the round cylinder poking out in from your cam.. yeah, the one you point to your gf face"...
    Read the Photographic notes for newbies as first reference. See what the shutter does, then the term 'shutter speed' becomes clear. Focal length is the most important parameter of the lens and defines what you see in the picture. The rest is basic Maths.
    thanks for pointing out that link. i have already read and i knew about what shutter speed is, focal length, aperture. it's just those equations that i wanna make myself clearer so as to reduce any mistakes in future

  7. #27

    Default Re: auto focus points + image stabilizer inquiries

    Quote Originally Posted by rockdhop View Post
    thanks bro. thanks for the clarification. truly appreciate it.
    No worries man, sharing is caring!

  8. #28

    Default Re: auto focus points + image stabilizer inquiries

    hey you from hardware zone right? lol. how's ur gt ava?
    actually hmm the required situation when IS comes in, is when you zoom far right?and shutter speed is slow,and aperture is wide?

  9. #29

    Default Re: auto focus points + image stabilizer inquiries

    Quote Originally Posted by rockdhop View Post
    hey you from hardware zone right? lol. how's ur gt ava?
    actually hmm the required situation when IS comes in, is when you zoom far right?and shutter speed is slow,and aperture is wide?
    Yup, I quit cycling and sold my bike some months back, money all go to camera liao.

    IS is always working regardless of focal length unless you switch it off. What it does is to give you 2 to 3 stops more of shutter speed, my 18-135 is reviewed and rated up to 4 stops.

    Eg, you are at say 18mm, you will need to have at least 1/20s shutter speed right? with IS enabled, you can stop down to maybe 1/10s(1/15s, 1/13s, 1/10s), that's 3 extra stop of shutter speed. Now you will ask, why do I need to stop down since I can do 1/20s easily? Well, with the extra stops of shutter speed, you allow more light to enter the camera, hence you can have the option of not bumping up your ISO which will translate to less noisy pic.

  10. #30

    Default Re: auto focus points + image stabilizer inquiries

    Quote Originally Posted by tecnica View Post
    Yup, I quit cycling and sold my bike some months back, money all go to camera liao.

    IS is always working regardless of focal length unless you switch it off. What it does is to give you 2 to 3 stops more of shutter speed, my 18-135 is reviewed and rated up to 4 stops.

    Eg, you are at say 18mm, you will need to have at least 1/20s shutter speed right? with IS enabled, you can stop down to maybe 1/10s(1/15s, 1/13s, 1/10s), that's 3 extra stop of shutter speed. Now you will ask, why do I need to stop down since I can do 1/20s easily? Well, with the extra stops of shutter speed, you allow more light to enter the camera, hence you can have the option of not bumping up your ISO which will translate to less noisy pic.

    thanks for telling me that. so having more stops = allowing closer gap against the 1/focal length theory right? and having slower speed also allows better image quality right?

  11. #31

    Default Re: auto focus points + image stabilizer inquiries

    Eh, I dun understand your question..

  12. #32
    Moderator Octarine's Avatar
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    Default Re: auto focus points + image stabilizer inquiries

    Quote Originally Posted by rockdhop View Post
    thanks for telling me that. so having more stops = allowing closer gap against the 1/focal length theory right? and having slower speed also allows better image quality right?
    No, still not clear. Back to math, Primary 5 I guess
    Example: Shutter speed is given as 1/60s. In maths terms this is a common fraction. Now, put opposite that a common fraction built from 1 / focal length (in mm). For 55mm focal length you get 1/55. Neglect the units, just put both fractions together and form an equation (or inequation, depending on result).
    Shutter speed: 1/60
    1/focal length: 1/55
    The guideline says: shutter speed must be faster (as Maths term here means: smaller) then the term "1/focal length" to avoid blur images due to camera shake. Or: if you have a given focal length (example: 28mm wide angle prime) your slowest shutter speed for handholding can be 1/30s. Verstanden? - Some people incorporate also the crop factor of 1.6x (Canon): 55mm*1.6 = 88mm = shutter speed of 1/100s at minimum.
    Next: IS and the additional stops. (I presume you know what 'exposure stop' means.) With a lens equipped with IS you can afford to lower the shutter speed by 3 or 4 stops (depending on the lens).
    Neither shutter speed nor IS has anything to do with image quality, unless we talk about blur due to handshake. Some images require 1/1000s shutter speed, others need Bulb exposure of minutes.
    EOS

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