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Thread: More focus points, good or bad?

  1. #1

    Default More focus points, good or bad?

    I've heard people saying D300 having 51 focus points being one of the major advantages over the lower end D90. (I believe similar statement exists for other brand also, so I pose this to the general forum.) I always use single point focus and always use the center focus point, so more focus points doesn't matter at all except the annoyance.

    I wonder if there are people agree with me. If not, what is your habit of focusing? I found switching focus points more troublesome than focusing then panning the camera. And the auto-selecting focus points is hard to control.

  2. #2
    Moderator Clown's Avatar
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    Default Re: More focus points, good or bad?

    it's necessary when the camera is mounted on a tripod and the subject you're trying to capture is off-center due to composition and you dont want to move the camera.
    plus the extra points help in subject tracking when you're on AF-C mode.
    sigh.

  3. #3

    Default Re: More focus points, good or bad?

    i haven't used a d300 so i don't know how the select af point mode works, that is what i use most of the time.

    but i find 11 on my system more than sufficient, if i have to focus on anything on the sides it means something is really wrong.

  4. #4

    Default Re: More focus points, good or bad?

    Quote Originally Posted by Clown View Post
    it's necessary when the camera is mounted on a tripod and the subject you're trying to capture is off-center due to composition and you dont want to move the camera. plus the extra points help in subject tracking when you're on AF-C mode.
    True. It's troublesome to pan on a tripod. Changing focus point is much easier.

  5. #5

    Default Re: More focus points, good or bad?

    Quote Originally Posted by night86mare View Post
    i haven't used a d300 so i don't know how the select af point mode works
    Oh, It's just pressing the up, down, left or right keys. It's easy to change af points, but panning is even easier.

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    Moderator Clown's Avatar
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    Default Re: More focus points, good or bad?

    actually if you're using extremely shallow DOF lenses (like the 85 f/1.2), focussing and recomposition will almost ensure your subject is out of focus. thus the need for off center focus points.
    sigh.

  7. #7

    Default Re: More focus points, good or bad?

    Quote Originally Posted by Clown View Post
    actually if you're using extremely shallow DOF lenses (like the 85 f/1.2), focussing and recomposition will almost ensure your subject is out of focus. thus the need for off center focus points.
    yes, that is for sure.

    it is already bad enough for say, 50mm f/1.4 wide open.

  8. #8

    Default Re: More focus points, good or bad?

    Quote Originally Posted by wuyongzheng View Post
    Oh, It's just pressing the up, down, left or right keys. It's easy to change af points, but panning is even easier.
    but scrolling through 51 points?

    i mean, certainly it won't be a scenario where i have to press 50 times to get from one point to the other, but i suppose at least 9 times in a dynamic (rather than static) situation would be painful!

  9. #9
    Senior Member wildcat's Avatar
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    Default Re: More focus points, good or bad?

    Quote Originally Posted by night86mare View Post
    but scrolling through 51 points?

    i mean, certainly it won't be a scenario where i have to press 50 times to get from one point to the other, but i suppose at least 9 times in a dynamic (rather than static) situation would be painful!
    I've had the same question for a while already and am glad someone asked it. I also use a centre point for focusing only and after focusing on subject, move the camera around to compose. So have always wondered why I would need 51 points of focus which may not be focusing on what I really want to focus on

    Isn't it faster (before the subject moves not only out of focus but arrgh... out of sight) to use the centre focus and move the cam then snap? Or does having 51 points of focus also help the centre focusing system to focus faster (somehow I don't think so but am not sure).

    Another question I have is, when there are 51 points of focus, how does the camera know which one of these to use? On my camera when I half press it (when not using the centre focus), it will tit tit tit and show a couple of focus points. But when I release and half press it again, it chooses different couple of focus points again. Like that, isn't it the camera deciding where to focus rather than where I want it to focus?
    Last edited by wildcat; 19th August 2009 at 03:17 PM.

  10. #10

    Default Re: More focus points, good or bad?

    I have not extensively use a system with a lot of AF points like 1D/1Ds but I don't see how it can be a full benefit (for me at least) unless it's all closely clustered. Cuz, am thinking if it's too sparse, wouldn't there be a chance of it focusing on wrong subject / place during AI Servo (i.e. AF-C) causing the intended subject to be off-focus?

    Perhaps for me, what I prefer is just accuracy and speed of AF than points...

  11. #11
    Moderator Clown's Avatar
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    Default Re: More focus points, good or bad?

    yes of course its faster to focus and recompose.
    but the high number of focus points are for the purpose of tracking your subject in nature and sports photography, and also in situations when you are not supposed to move the camera at all but your subject is off-center.
    sigh.

  12. #12

    Default Re: More focus points, good or bad?

    More focus points also require faster/smarter AF alogorithms or else you'll get random AF locks.

    But yes, it helps compose things easier when you have more points to select.

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    Default Re: More focus points, good or bad?

    I know a few people swear by the 51 point thingy but I really didn't get to find out what's the advantages they are enjoying coz I didn't asked. For me who is using mainly manual lenses, the cluster is really more of a hindrance than assets.
    651D90 Mk II cameller™ ...... "Ai Camel Mai ?"

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    Senior Member Big Kahuna's Avatar
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    Default Re: More focus points, good or bad?

    Depending on situation, for fast action, I prefer 11 points......51 points is more suitable for static object

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    Default Re: More focus points, good or bad?

    I've tried the 51-point system on a D700 and it tracks very very well. I'm actually very impressed (and that's coming from using a 1DII before too). I used to shoot with center point only, and now I still do (with a 9-point only 5D), but when I had the 45 points on a 1DII, it made everything a whole lot easier.

    Yes, these 45/51 point systems are a lot more accurate even though there are more points.

  16. #16

    Default Re: More focus points, good or bad?

    51 AF points on the D300 and 15 cross ones clustered in a 3x5 column. if u are using af tracking, it will so much better than using 1 single af point. just cos u dun use it doesn't mean its useless. thats the funniest comment i see here.

    the d90 only has 1 center cross af point. 1 vs 15. no brainer really.

  17. #17

    Default Re: More focus points, good or bad?

    It depends a lot on what one shoots and how one works and how configurable the AF system is.

    For me it's a no brainer - the more the merrier and I can always limit the number of selectable points if need be. You can't ever expand if there aren't enough points to begin with. Shift, focus and recompose is often a compromise in accuracy, and under certain circumstances, simply not an option.

    When working in manual focus with electronic focus confirm like when working with TSE or PC-E lenses, or chipped adapters, having more points means that I can select, with a lot more precision, exactly where and what I want in focus. Moving the camera/viewfinder is exceedingly counter-productive when working with technical lenses and results in gross inaccuracy. Having 45 or 51 points to select from made that a breeze and it worked (for me) even with moving on the streets candids. I've also used that for running/jumping kids shot with TSE lenses.

    Another important factor related to an earlier comment is that AF performance depends a lot on how well one understands how the AF system was designed to think and react. Sometimes, it's not a matter of having 45 or 51 AF points and that would guarantee near-perfect results say in high-speed sports photography even in bright daylight. Under different circumstances and lighting, I need to tailor the way my AF points behave in order to increase keeper rates.

    I'm not sure about the D700 and how many micro-processors it uses for what functions, but on the whole, I find AF a lot more aggressive on Nikon's upper end bodies as compared to Canon's. Sometimes, I wished I had that aggressiveness and sometimes, not. NO, this is NOT a brand war so please DON'T make it one! What I do know is that on Canon's famed 1D2 body, the AF is highly configurable and that body uses two micro-processors instead of one to handle AF and other camera functions separately = faster performance and responsiveness. What I do know about the D700 is that it's quite a bit easier to manual focus on the groundglass using the stock screen from firsthand experience and that the AF works quite wonderfully from what I hear!

    TS, if you really want to know more, try and find the technical papers usually written by outside engineers and consultants about how a particular camera's AF system works in real life. As for your original question, only you can decide what works better, and not, for you and under your own circumstances and such. Assuming a fair degree of understanding has been reached, buy your next camera suited to YOUR needs instead of what's the latest and greatest or what others say.

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    Default Re: More focus points, good or bad?

    Quote Originally Posted by wuyongzheng View Post
    I've heard people saying D300 having 51 focus points being one of the major advantages over the lower end D90. (I believe similar statement exists for other brand also, so I pose this to the general forum.) I always use single point focus and always use the center focus point, so more focus points doesn't matter at all except the annoyance.

    I wonder if there are people agree with me. If not, what is your habit of focusing? I found switching focus points more troublesome than focusing then panning the camera. And the auto-selecting focus points is hard to control.
    More of cos is better. Reason being i can select the point i want which is closest to the part i'm focusing on with as minimal recomposition as possible, cos sometimes recomposing can cause focus to be out.
    Canon EOS 5D, 24-70 f/4 L IS, 50 f/1.2 L, 70-300 f/4-5.6 L IS, 600EX-RT. Sigma 12-24 f/4.5-5.6 EX.

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    Default Re: More focus points, good or bad?

    you should try to use fast lens(50f1.4, 85f1.4...etc) wide open focus and recompose, see the result then you will know why more is better.

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    Senior Member limwhow's Avatar
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    Default Re: More focus points, good or bad?

    Quote Originally Posted by Clown View Post
    actually if you're using extremely shallow DOF lenses (like the 85 f/1.2), focussing and recomposition will almost ensure your subject is out of focus. thus the need for off center focus points.
    Quote Originally Posted by night86mare View Post
    yes, that is for sure.

    it is already bad enough for say, 50mm f/1.4 wide open.
    Yeah... now that you both mention it. I found that to be the case for my 50mm f/1.4 too.
    One of the experienced photog ever pointed out that to me. But it really took me some time to realise my own stubborn-ess.
    And that is why nowadays when I use lenses wide open, I tend to keep scrolling through the AF points to off centre.
    But when I do this, what problem do I get? I realise that the Spot metering or Partial metering becomes inaccurate because my subject is focused off-centre, but the centre of the VF is metering another spot away from the subject...

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