Multiple Focus Points

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  • #3427
    Profile photo of Dennis Crabtree
    Dennis Crabtree
    Participant

    After a break of many years from photography I notice our digital cameras now have multiple focus points.  I think this feature has led to many of my shots being poor because the main part of the subject is out of focus.  I believe this is because the camera has focused on the closest part of the scene to the lens.

    My camera has small red lights in the viewfinder to indicate the point or points that have found focus but I find it hard to concentrate on them and compose the shot as well.  In the old days I only had one focus point, (in the middle of the viewfinder) and that seemed to be perfectly adequate.

    I’m now about to start shooting with only the centre focus point active as I’m sure this will make my life easier with a higher success rate re’ focusing.

    Questions:-

    a)  Why do we have multiple focus points?

    b)  How do other members manage their focus points?

         Your answers and views will be much appreciated here please and not on a postcard.

     

    #3428
    Profile photo of D. Williams
    D. Williams
    Participant

    Individually setting the focus point depending on the shot  has become a habit to me now Dennis and has made a massive difference to the number of sharp shots I get particularly where people are involved and in street shots. I am now quite fast at doing it but it took a while.

    The more off centre the point of interest,  busier or more blurred the background the more important it is.  I also change the FP depending on if I am shooting in portrait or landscape placing the dot on the part of the image I want in focus ie the subject and not the BG.  With a portrait format  people shot this will probably not be the top point but one down on either side placed on the nose or eyes of the subject depending on their place in the frame. I constantly check and adjust.In some recent portraits a central focus point would have hit the subject in the neck area and the eyes would have missed out. I do think it is unusual to have your main point of interest bang slap in the centre of the image.

    I find it also helps as I often shoot in poor light at f2.8 – 4 to get a faster shutter speed and I need to make sure the face / subject is the sharpest bit.  It is one of the first things I check and adjust before taking a shot these days. I mainly shoot in Manual.

    I can see our pro’s raising their eyes to the heavens at this lot … but it works for a relative beginner like me! :wink:

    #3429
    Profile photo of
    Anonymous

    On the contary my dear Watson—-er delete–Williams—you have your system well worked out  and all credit to you–sound excellent and it works for you well. In other words–you know what you are doing.

    #3430
    Profile photo of D. Williams
    D. Williams
    Participant

    I am sort of getting there Ken but lots to learn yet.  Twelve months ago I was still using auto settings and the odd creative auto.  It has taken this long to get my head around the more manual settings and how and when to apply them.  Mainly thanks to Meg and Pete drumming it in to me.

    I don’t know what you shoot and what mode you shoot in Dennis or which metering option you choose ie evaluative / spot / centre weighted etc.  That can also make a huge difference.

    The rest of the gang will be able to give you some sound advice I am sure.  There are lots of different ways of achieving the results you want and we all have to find the one which suits us best.

    #3431
    Profile photo of Dennis Crabtree
    Dennis Crabtree
    Participant

    Interesting, I did do a bit of reading up on http://www.cambridgeincolour.com/ and it seems that the majority of people use the centre focus point the majority of the time.  For most of my shots I use Av mode with ISO set to auto but limited to a max of 400.

     

    I then adjust for the highest f number while maintaining an acceptable hand held shutter speed this I feel should result in crisp clear shots (my favourite).

     

    I haven’t experimented with metering mode yet but have come to realise that before pulling the trigger I should consider using the following in this order:- AE Lock, focusing on the point of interest then re composing the shot while the shutter button is half pressed.

    #3432
    Profile photo of Ian McNab
    Ian McNab
    Keymaster

    For most hand-held work I use only the central focus point. I focus on the important element, lock the focus, and recompose to get the composition right (or as near right as I can, not being Cartier-Bresson!). Locking focus on my Nikon DSLR is easy with the rear focus button – just press it once, and it’s locked till you press it again, regardless of how many time you release the shutter. I shoot mostly Manual mode + spot metering on the DSLR to get total control; but it’s slower, of course.

    For street work with the X100, I tend to use Aperture priority, with AutoISO set to raise the ISO if the the shutter speed would drop below 1/100 (a value that’ll freeze motion for most street shots); but, to avoid excessive noise, the max ISO is set to 3200, above which the shutter speed will start to drop. This lets me concentrate on faster composition in the simple, quick way that’s essential for street photography.  For the same reason, I often use range focussing on the street: focus manually, and lock the focus at 8 feet; set aperture to f/8; that’ll ensure things between about 5 feet and 20 feet are in focus without having to bother with autofocussing repeatedly – just compose and shoot: the classic street technique!

    #3433
    Profile photo of Ian McNab
    Ian McNab
    Keymaster

    Why so many focus points?  Well, one reason is to enable cameras to select where to focus automatically, though, as Dennis said in the first post above, this can be risky!

    Another reason may be that the “centre-focus and recompose” technique can put the recomposed image out of focus under some circumstances, in particular with wide apertures when the main, off-centre subject is only a short distance from the camera and the focal length is longer than about 50mm full-frame equivalent.  This is because under those circumstances the depth of field is very narrow, so rotating the camera through an arc by recomposing can take off-centre subject out of the plane of focus.  Keeping the camera still, and selecting the right focus point avoids this problem.  (In practice, it’s only a problem in some very limited circumstances, as I described, where there’s too little latitude.)

    #3435
    Profile photo of D. Williams
    D. Williams
    Participant

    Very interesting Ian.  I have not got into using AE lock myself but it is on my to do list.  I do sometimes change metering modes depending on the subject but mainly use evaluative at the moment as it seems to give me the best results for what I shoot. My success rate went up when I switched to it. I do mainly shoot people though.

    As the info below, which is from the Canon site explains it is the most common used amongst canon users and the default setting in auto modes.  As it works around the selected focal point and I select that by hand and then also reads the rest of the scene my hope is that I am getting the best results I can.  However in certain circumstances (landscapes etc) I would be better of changing to another method especially if I get my head around AE lock.  I never go above an ISO of 800 handheld unless I absolutely have no option as I personally rarely get a really sharp shot.  I can’t really use a tripod on the hoof which is a shame as it would make a difference.

    I think the answer is always to experiment.  I suspect that your way is best Ian as I have only a fraction of your knowledge and experience but  have arrived where I have by trial and error.

    From Canon USA

    Evaluative: Metering is directly linked to, and concentrated on, the area around the active AF point, whether you’ve focused on something in the center or off-center. Light values measured at the active AF point are compared with light values measured from the metering segments across the remaining areas of the scene, and the camera’s metering system attempts to provide an accurate exposure based on that comparison. This metering pattern is often effective when photographing people, but may not be quite as effective when photographing snowy landscapes depending on other elements in the scene. Note that because Evaluative Metering is linked to active AF points, focusing on a different subject may result in a very different exposure — even within the same scene. Note: In the simulated viewfinder, Evaluative mode is shown with the left-most AF point active.

    Spot: The most selective metering option, it reads exposure information only from the single exposure zone in the center of the frame (approximately 3% of the total picture area)

    Partial: Similar to Spot Metering, but covers a slightly larger area, reading only the cross-shaped central five metering zones (approximately 10% of the total picture area) — some shooters think of it as a “fat spot”

    Center-weighted Average: This metering mode averages the exposure for the entire metering area, but with greater emphasis on the center metering zones. Unlike Evaluative metering, it does not compare brightness readings from different parts of the scene; it simply reads overall brightness.

    Even though Evaluative metering is by far the most commonly-used system by EOS users, when using one of the EOS Creative Zone exposure modes (M, Tv, Av, P, or A-DEP), you can select from any of the metering modes offered on your camera. If you prefer to shoot in the Basic Zone exposure modes (Full Auto, Portrait, Landscape, Close-up, Action, etc.), the default mode is usually Evaluative.

    #3437
    Profile photo of Ian McNab
    Ian McNab
    Keymaster

    Dee >>> I wasn’t referring to AE – the exposure lock, but to what, on a Nikon, is called AL – the focus lock. Locking the focus just means the focus doesn’t readjust if you take your finger off the shutter and then press it again.

    As for exposure metering, I do use the equivalent of ‘Evaluative’ metering on the Fuji X100, as I’m normally in Aperture Priority mode, and compensate for the meter using Exposure Compensation. (Remember, the meter is trying to expose everything as if it were overall mid-tone grey; but snow scenes, or black cats on a pile of coal, aren’t!   We famously see the result of relying on evaluative metering when the loving new husband photographs his beautiful wife against a glorious sunset and turns her into a black silhouette.  Should have added a stop or two on the Exposure Compensation!)

    If you spot meter, and set the exposure manually, you correct for this sort of metering error as you adjust the settings by exposing the young lady’s fair skin about a stop above what the meter is saying, or her white wedding dress a couple of stops over.

    #3438
    Profile photo of D. Williams
    D. Williams
    Participant

    Aaah sorry for the confusion Ian. I do also use exposure compensation these days and try a couple of test shots in the given light if I have time. So much to learn and remember in this game.

    I will try focus lock. Manually selecting the points is my normal method as I said and I can change them in about a second but your way sounds interesting and I will read up and give it a go. Anything for consistent results.  Hope all this is helping and not confusing you Dennis.

    Wish this damn bug would go away and leave me alone! 🙁

    Taken with manual focus point on / between the eyes ish.  I don’t think a centre focus point would have  givem as good a result  in this case.  Am I right Ian.  Not sure now.

    Close up

    #3439
    Profile photo of Peter Robinson
    Peter Robinson
    Keymaster

    Hello again. Remember me? Sorry I’ve been AWOL for a few weeks. This is an interesting topic. Like Ian, I use the the center focus point to focus and hold my shutter button half way down to lock the focus, then recompose my frame. Like Ian says you can lose critical focus if your using a wide aperture and have to recompose far from the point you focused on. Another problem with this technique is that if your subject moves it will be out of focus. So if you follow D’s technique it should be quicker after you’ve changed the focus point and more accurate as you dont have to recompose as far. It would also be easier to reset the focus.  I think the shot above proves how well it works.
    If I’m photographing something moving towards or away from the camera I switch from Canon’s ‘One Shot’ focus setting which locks the focus when the shutter is pressed, to ‘A1 servo’ which will follow the subject. Then I have to keep the centre point on the subject so I may not get the composition I want.
    The other issue is the exposure that Ian has already explained. I like his street photography technique which enables him to shoot accurately and quickly. Like Dennis says, if I think the camera won’t give the correct exposure based in the centre focus point I take a exposure reading from a ‘grey’ area first and lock it with a button on the back of the camera with my thumb, then set the focus by half pressing the shutter. Then I cross the fingers I’ve got left!

    #3451
    Profile photo of D. Williams
    D. Williams
    Participant

    Who are you and what have you done with Pete? :lol:

    Actually I think it was you who brought manually setting individual focus points to my attention and it has been a huge help.

    #3595
    Profile photo of D. Williams
    D. Williams
    Participant

    My point on this using the portrait to illustrate was that it would be best to get into the habit of either locking focus and recomposing or setting an individual focus point as I do rather than rely on any kind of automatic central focus point.  Just use which method is easiest for you personally and soon it will become a habit.

    #3596
    Profile photo of Ian McNab
    Ian McNab
    Keymaster

    Dee >>> re your March 10 6:06pm post, no I don’t think centre focus alone would have done it.  I always use centre focus to lock focus on the important thing (in your portrait, I’d have gone for the eye nearest the camera / centre of the frame:  her right eye, here) and then RECOMPOSE to get the composition right.

    I find it just too fiddly to scroll up/down/across manually to the correct one of the 51 focus points the Nikon D300s has!  I accept it’s probably easier with less-sophisticated Canon cameras 😉 😉 😉

    #3597
    Profile photo of
    Anonymous

    I do not see the point of re-ajusting exposure for “spot metering”.Spot metering is the one tool to give really accurate exposure of a given subject.Any need to fiddle about then spot metering is the wrong exposure mode. The single white flower against a black background or vice versa   and the subject will be perfectly exposed. Bride in white dress and groom in black suit–spot metering is not the mode. Portrait–spot meter the face for correct exposure of the skin to be spot on.All other modes are a bit ifish and average–spot metering is to give spot on exposure for a specific point. Regarding focussing modes, automation has made something simple  –complicated. On both my Leica V-Lux and Panasonic  the manual focus is easiest, as the manual focus button is under the thumb of left hand cradling the camera. Aim at subject to be in  focus and press manual button -then however much I wave the camera about to compose– the subject will be in focus.  Just done an extreem test on a ten point font letter at four meters away –with 450mm tele setting  in room lighting and the manual button gave me sharp focus in a split and could read the print dead sharp.

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