Lots of Focus Points

[Raid]

<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language: EN-US;"]<o><span style="font-family: Calibri; font-size: small;"]</o>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language: EN-US;"]<span style="font-size: small;"]<span style="font-family: Calibri;"]With the impending release of the 1D X with its lots of focus points. There has been a lot of discussion about how good this will be. From all of the information I have gleaned from books, articles and even professional photographers, they have all talked about using a single focus point. <o></o>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language: EN-US;"]<o><span style="font-family: Calibri; font-size: small;"]</o>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language: EN-US;"]<span style="font-size: small;"]<span style="font-family: Calibri;"]Well at the risk of highlighting my ignorance, when do you use lots of focus point?<o></o>

[Dr Croubie]

On my 7D, with its glorious number of 19 AF points, I generally only ever use the

[Richard Lane]

<p class="MsoNormal" style="margin:0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language:EN-US;"]<span style="font-family:Calibri;font-size:small;"]
<p class="MsoNormal" style="margin:0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language:EN-US;"]<span style="font-size:small;"]<span style="font-family:Calibri;"]With the impending release of the 1D X with its lots of focus points.... From all of the information I have gleaned from books, articles and even professional photographers, they have all talked about using a single focus point.
<p class="MsoNormal" style="margin:0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language:EN-US;"]<span style="font-family:Calibri;font-size:small;"]
<p class="MsoNormal" style="margin:0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language:EN-US;"]<span style="font-size:small;"]<span style="font-family:Calibri;"]....when do you use lots of focus point?

I'll make an attempt to clarify what I thinkis happening depending on which article you read, some of the reviewers use the term "single AF point" and that confuses people with "single center" AF point. There are two ways of selecting AF points; one is by letting the camera decide called "Automatic AF Point selection," and the other way is by "Manual Point selection" in which you decide which point to select.


People can let the camera choose between "a lot of AF points" when using Automatic AF point selection, that is when the camera decides which sensor points it should use, but that is very unreliable since the camera is technically guessing what you would like to focus on. The camera usually focuses on the forward most subject in the frame or the subject with the most contrast. Most people except for beginners will never use this setting.


I'm less familiar with the new 1D X focusing system, but hopefully I can clarify what the confusion may be, when you're reading about the AF specs. For example, on the 1D MKIV, when choosing Automatic AF point selection (letting the camera choose the points) with an f/2.8 Lens, the camera will only choose amongst 19 points for Camera decided AF point tracking, however when the photographer selects a "single point AF selection manually," that means that they have chosen where to start the tracking process amongst the 45 points that are available (this becomes more accurate since you will pick the correct point that benefits your subject regardingthe compostional starting point.Theuserwill now have45 points to choose from ("also a lot") for tracking (39 of those points are cross sensitive and 6 are horizontal sensitive) when using an f/2.8 lens.


I think the terminology confuses people, since "single point manual point selection" sounds like there are less points available to you (because of the word "single") as oppossed to Automatic AF selection, however, remember that this single point is just where the AF starts but you also haveother points (45 points) availableto choose from when compared to Automatic AF point selection (19 points). A better term than single point, would be "manual point selection," but since it's AF and not manual focus, they sometimes call it "Single Point" AF Manual selection. Single point AF manual selection does offer"a lot" of AF pointsfor AI Servo tracking.


Another term is "the single center point"when someone chooses this,they are in fact limiting the focus point to onesingle "center point" only, which on lower camera models is the most accurate, however, when you go up the Canon line to the more expensive models like the 1D MKIV, then the 39 cross sensor points are still very accurate for AI Servo tracking, plus you have more points availableto choose from.


So when you're reading these articles note the difference between "Single point AF manual selection" and the difference between "Single center point selection" and "Automatic AF Point selection".


I hope you got mypoint.


Rich

[neuroanatomist]

I think Rich's explanation is excellent. To summarize, most photographers use 'single point' in that they select which AF point to use, rather than letting the camera do that for them. Generally speaking, having more points is better for AI Servo tracking of moving subjects. Having lots of points could make manually selecting a point slower, e.g. 5 presses of the joystick to get from center to side, but previous 1-series bodies have have C.Fn options to limit the number of available points for manual selection, and likely the 1D X will have similar options.

[Rocco]

To expand on what neuro said, using a single point is great for portrait work, macro work, etc. Especially when using a shallow depth of field. i.e. using a single af point to focus on the eye of your subject. Like him, I also use more points for fast moving subjects like wildlife (never know when they

[bob williams]

Raid, The two big reasons I like the idea of "lots of focus points" are as follows:


1. When you select a focus point, it doesn't have to be the middle one---the more focus points you have the more likely you are to have one that falls where you want on the subject, such as an eye. More focus points normally offer greater frame coverage (although this hasn't always been the case, for the 1DX they have spread more focus points over a wider area of the frame--acoording to he literature.


2. When shooting sports, wildlife or fast moving subjects, I like using zone focus where the camera selects the point based on the zone or area of the frame you are trying to keep on the subject. The more points you have, the larger or more variety of zones will be available.


hope this helps

[Raid]

Thanks everybody


I have never attempted to use lots of focus points before, I will give it a try and see what happens.

[Richard Lane]

Raid,


The goal is not to arbitrarily use lots of focus points at once, it's more about selecting the right point or points for better precision and tracking composition. The goal is to only have the camera focus on your subject while ignoring the other components in the frame.You'll have lots of focus points to choose from by using "single point" AF manual selection. You can choose these points by using the multi-controller or the manual AF point selection button (in the back of the camera). I'm not sure which camera you have. Once you select your point, then you'll want to have that point locked onto your subject while you try to track it.


Once you understand this concept, then you can add "extra" focus points to your single point selection. You can add these extra surrounding points; above, below and to the sides of the single point that you had selected manually. These points will take over the focus if your single point should temporarily lose your subject. I highly recommend this feature when tracking difficult subjects.


As Bob has mentioned, the 7D also has zone AF which will allow you to pick a certain zone on the sensor for it to AF on your subject. So.., as long as you keep your subject in that zone then you'll be fine.


If you're interested I can go into more detail. Just let me know if you have any questions.


Rich

[Raid]

Thanks everybody


I have never attempted to use lots of focus points before, I will give it a try and see what happens.

[neuroanatomist]

More focus points normally offer greater frame coverage (although this hasn't always been the case, for the 1DX they have spread more focus points over a wider area of the frame--acoording to he literature.

This subject comes up quite frequently. In fact, one of the (or at least, one of my...) chief complaints about the 5DII's Af system is the relatively inadequate spread of the AF points. Canon advertised the fact that they have the same lateral spread as the 1DsIII, but conveniently omitted the fact that the vertical spread was much less (a full 'row' of points less), meaning the 'corner' points of the 5DII come no where the rule of thirds.


A common question is, "What does the relative spread of AF points look like?" On the web, I ran across a file which has scaled versions of the focus screen representations of the AF points for the 1D IV, 5DII, and 7D. I took that file, and added in scaled versions of the points for the 1DsIII and the 1D X:


[img]/cfs-file.ashx/__key/CommunityServer-Components-UserFiles/00-00-00-35-15/xD_5F00_Focus_5F00_Screens.jpg[/img]


The 1D IV 7D are about tied for the broadest spread in both dimensions (relative to frame size). The 1D X has the same lateral spread as the 1D IV and 7D, and slightly less spread in the vertical dimension (about half a row shorter). The 5DII is in blue, and you can see the narrow spread relative to the other xD bodies.


The above image is pretty busy. But, if you click the image, you'll get a download of a layered pdf file. If you open that in Photoshop (CS, even Elements, I tried as far back Elements v6), you'll see each of the xD bodies' AF points in a separate layer of the file, along with a layer showing a rule-of-thirds grid. You can toggle them on and off as you like to compare the spreads.


Enjoy!


--John