How Many AF Points Do You Have ??

[dje]

Well, I only have 9 on my T3i/600D . (and only the centre one is a cross type). But I seem to be able to get by, at least with the type of photography I do (landscapes, cityscapes, some wildlife).

More up-market cameras have a lot more AF points(eg the 7D has 19 points and the 5D Mk III has 61 points)

So my question is – when and how do you use all these extra points ?

My usual technique is to use manual AF point selection and always use the centre point. This means that I have to point the camera so that the centre point lies on the object I wish to use as my focus point, lock in the focus and then re-compose the shot. If I’m using a tripod, I might consider keeping the camera fixed and selecting an AF point other than the centre one but generally I don’t bother. I suppose this might be a circumstance however where the larger number of AF points would be handy ?
If I’m using a tripod under low light conditions, more often than not I use manual focus. (Using the magnified Live View mode)

I never use automatic selection of the AF point as there is too much uncertainty with this for me.

I would be most interested to hear about the techniques that others use.

Dave

[Glenn NK]

I really don't know (could check), but it doesn't matter because I have only the centre one active.

Because most of my photography is either macro or landscape, AF is actually not much use. To clarify, I use a manual focus 24TSE lens for landscape, and AF is pretty well useless with macro (20 focus stacked images demand manual focus).

Glenn

[rtbaum]

I'm finding that really is dependent on what type of photography; General landscapes - center weighted, macro - manual, super telephoto - center point or manual. I really can't remember for sure how many AF points the D90 has, it was a great sales point though

[ofer4]

Dave -

I'm using a Pentax K-r, which (I believe) has 11 AF points. I tend to use the center point most often, as well. However, I think one of the benefits of having more points is that each individual point gets smaller. Therefore, even if you rely on the center alone, the chances are lower for that center "point" finding something else within its region on which to focus. I have encountered many situations where my subject ends up out of focus because AF locked onto something else within the focus region. The "points" are typically (much) larger than the little squares in your viewfinder.

Ryan

[Inkanyezi]

I don't use a DSLR, but have been using mirror-free cameras for some time. My present camera is the Olympus OM-D, and I am unsure whether there are any "AF points" in that camera. I use varying strategies for focusing, mostly including choosing a point where to focus, anywhere in the viewfinder or on the screen. I hardly ever let the camera choose where to focus. Most convenient is to use the flip-out touch screen and choose the focusing point by pointing with a finger, whether using AF or focusing manually.

I don't think that a multitude of discrete "AF points" would be a great help in choosing where to focus, and I have had bad experience letting the camera choose where to focus, so I prefer to choose my focusing point myself, position as well as size. If there were no choice, I would prefer one single small point.

[dubaiphil]

Well cross point focus points are generally more accurate. I'm pretty much always using my centre point and then recomposing. I lock focus on the part of the subject that I want, hold the AF-On button with my thumb, recompose and click. Much easier for me.

Unless I'm using a prime lens wide open, in which case the recomposing can mean that the focal plane has moved slightly and I miss focus - then I'll rely on an off centre cross point focus point.

So in total my camera has 51 point autofocus. Very very occasionally I'll use 3D tracking, or 51 point, or even 9 point with fast moving objects. 99% of the time I'm just using the one point.

[davidedric]

I'm pleased to read this thread. I'd been feeling a bit inferior with my 9 points and hardly ever using them - and with no idea how I'd manage 51. I use the same technique as Phil.

[Shadowman]

I had only 3 AF pts on my first DSLR (still use it) and 11 on my mirrorless and new DSLR.

[Mark von Kanel]

got 39 of the little blighters i think but like yourself i use the center one mostly, changing them is easy enough with the thumb but i dont tend to think about it much its easier to focus and re compose. Kind of makes you lazy though, i really must practice manual focus more often...

[Clactonian]

It's not what you've got but the way you use it!!
If you are using single point focus then the ability to focus using an off centre point without recomposing can be useful. Similarly if you are using some of the more sophisticated focus modes such as closest subject, then more focus points can be of benefit. The same applies when you are focus tracking a moving subject in the appropriate mode, the more focus points the better the chance of maintaining focus. Well it sounds convincing anyway!!

[stelin]

I am blessed (cursed??) with lots.
I tend to use centre point in general, manually select where appropriate with static objects, (particularly posed people), and a variety of different modes when shooting planes, birds in flght, cars etc.
Just using the centre point only when shooting birds in flight is nigh on impossible unless you have the reactions of a fighter pilot.
Steven

[northlondon43]

I simply love threads like this where I have no idea what you're talking about but you do it with such gusto :-) p.s. I have 7.5 million AF points, erm that's a lie

[Colin Southern]

I've got 61 on my 1Dx, but how many that are actually available depends on the lens that's attached.

In reality, having that many gives 2 advantages:

1. More to choose from, so that I can get better compositions (and good focus) (eg still keep an AF point on a model's eye, but place them in a different part of the frame), and

2. AF assist points are closer to the primary point, again, assisting in getting good focus.

[dje]

Thanks everybody for your comments, it's interesting (and somewhat re-assuring) to see what others do.

2. AF assist points are closer to the primary point, again, assisting in getting good focus.

Colin you refer to AF assist points which is a term I haven't heard before - are these different to AF points ?

Dave

[davidedric]

Just using the centre point only when shooting birds in flight is nigh on impossible unless you have the reactions of a fighter pilot.

I'm no Top Gun, but that's the way I try to do it. I'm starting a thread in "Nature and Architecture" to ask the experts their advice.

But, just for the record, taken using the centre point

[jcuknz]

If I want it I have an infinite number of posssible target areas with my touch screen ... though in practice I have only done that once in the past year. Far more important is the size of the target area and once again I believe I have a much smaller area than most/any other camera which I believe is valuable if you want to use AF in a similar manner to MF and critically pick the point you want to focus on ... once again practice doesn't always match the theory ... the doe/hind's head in an adjacent thread is sadly not only B&W but not really sharp. Panasonic G3 has this feature but the GH2 doesn't that I have found as yet.

[stelin]

I'm no Top Gun, but that's the way I try to do it. I'm starting a thread in "Nature and Architecture" to ask the experts their advice.

But, just for the record, taken using the centre point

If you have a nice big slow bird not too far away then it works nicely.
For faster/smaller/further birds taking less of the frame, I don't find that it does.
(Nice image but a little fuzzy)

[Colin Southern]

Thanks everybody for your comments, it's interesting (and somewhat re-assuring) to see what others do.



Colin you refer to AF assist points which is a term I haven't heard before - are these different to AF points ?

Dave

Basically they're just regular AF points - but - they may or may not be ones that are user selectable, depending on the camera. eg the 20D had 15 points (off memory), but only 9 were selectable.

On the 1Dx one can tell the camera what it wants to do; for example, when I got the 1Dx I was disappointed at the number of OOF shots in my first studio shoot ... for that shoot I'd selected single point spot AF and the camera was just getting it plain wrong too often. What I use now is normal AF (not spot AF) with surrounding 8 AF points to be used as assist points. Basically what it means is the selected AF point is still "the boss", but like a good boss, it'll confer with those around it, and if they all think the "boss is wrong" then it'll probably "go with the majority" whereas if most agree with the boss then it probably made the right choice in the first place.

Since then I've not had any AF problems.

[Colin Southern]

(Nice image but a little fuzzy)

At a guess I'd say it's been heavily cropped - the levels pushed hard in PP - and not sharpened optimally (if at all).

[dje]

Thanks for the explanation Colin.

but like a good boss, it'll confer with those around it, and if they all think the "boss is wrong" then it'll probably "go with the majority"

I never had a boss like that !!

Dave