Focusing - recomposing.

[Dan1502]

I tend to use the different focus points on my 50D quite a lot and without looking it up believe it works in a similar way to the 7D but with less points (9 I think). I'm meaning to set the joystick to allow easier changes of the focus points but haven't got around to it yet. In fact the one thing I would like about a 5DII or similar is the increased number of points to aid composition as I often find even using the focus point closest to the point I want I still have to recompose slightly. The next thing I want to try with landscape shots is hyperfocal distance but I have to get my head round it properly first.

 

[The23rdman]

Same as Ryan, I don't use the tracking. I'm generally shooting reasonably static subjects but there is enough movement between them and me to get it wrong so I use the (11 from memory) AF points and just shift to the closest on to the eye and place it on the eye I want in focus. That's for shooting portrait/head shots.

For things like groups I'll just use the central one and shoot with enough DOF to get everyone sharp and if I have enough focus for the people behind then I know I'm OK for the foreground too.

The only time I'd conside switching to continuous is for a couple coming down the aisle at a rate of knots but I usually ask them to take it steady to allow me plenty of shooting time and not had a problem with them running yet

Ali, this is the exact method I use Ali, but find the 40d still requires me to recompose.

 

[The23rdman]

Well I'd take a lot of those opinions with a pinch of salt Dean, and I can only speak from experience of using it. I wouldn't be using the 7D if half of the opinions you read were accurate or based on experience of the camera, which often isn't the case.

I've a friend with one so I'll see if I can get hold of some shots to compare.

 

[ryanyboy]

The trouble with the 40D and many "lower end" (now I'm in trouble) cameras is the low number of focus points to choose from. With the higher end cameras you get more focus points and therefore greater scope to put the eye (or whatever) where you want it.

Of course it's still not perfect. Until they make a camera with focus points across the whole of the view finder we're always going to be limited to a degree.

 

[markrichardson]

The trouble with the 40D and many "lower end" (now I'm in trouble) cameras is the low number of focus points to choose from. With the higher end cameras you get more focus points and therefore greater scope to put the eye (or whatever) where you want it.

My problem is no so much with the number of focus points as with the apparent quality - but again I suspect that this is a 5d2 issue.

I think I'd be content with 9 if they were spaced as I'd like - one centre, one at each of the rule of thirds intersects, and one half way between each of the rule of thirds intersects.

 

[Jamieconverge]

i only really do portraits so i always just select a focus point manually, often going all over the grid! d300 has 51 to choose from and i never have a problem not having one in the right place. to be honest ive never used the tracking or auto point selection modes, i find it plenty quick and accurate enough to select my own, though im rarely shooting anything that moves much! i tend not to come away with any missed focus shots in a portrait shoot too.

with my previous cameras (d2x/d2h) i used to mostly use centre and recompose for ease. i really couldnt go back to using a camera with fewer focus points now a days.

 

[The23rdman]

The trouble with the 40D and many "lower end" (now I'm in trouble) cameras is the low number of focus points to choose from. With the higher end cameras you get more focus points and therefore greater scope to put the eye (or whatever) where you want it.

Of course it's still not perfect. Until they make a camera with focus points across the whole of the view finder we're always going to be limited to a degree.

It's not a lower end problem as much as a Canon problem. The equivalent Nikon body has more points to choose from.

 

[markrichardson]

It's not a lower end problem as much as a Canon problem. The equivalent Nikon body has more points to choose from.

I'm not convinced it's as much about the number of points as the quality of focus on the non-central points - certainly on the 5d Mark 2 (unless as I suggested earlier, it's a technique problem).

 

[desantnik]

I never use focus and recompose. Always use single focus point on the eye for head and shoulders type shots OR for other static things, yes, I use the Ken Rockwell all (51) the focus points and keep refocusing (quickly) until I get a pattern locked of a suitable coverage.

That being said, all of that is only possible because the D300/D700/D3 has so many focus points...

As an aside:

I've heard too many bad opinions on the 7d's iso performance to really consider it.

Well I'd take a lot of those opinions with a pinch of salt Dean, and I can only speak from experience of using it. I wouldn't be using the 7D if half of the opinions you read were accurate or based on experience of the camera, which often isn't the case.

I'd heard a lot about it too... then I saw what one of the MotoGP media togs had done with his last weekend... stunning (when coupled with many thousands of pounds of long prime) BUT by his own admission not as good as a D3... (IQ this is not, necessarily ISO - it was a blazing hot weekend). Colour rendition looked a bit out on the red (Ducati) bike of his shot too, but it was a stunning image none the less straight off the camera. So 7D is perfectly capable.

 

[trencheel303]

I skipped through the thread, but... from what I gather, you're not happy with the 40D so you want a move to Nikon.

Have you tried a 7D or a 1 series? I have no complaints about AF now and by the looks of it neither does CT.

To answer the question, I have two seperate focus buttons, one is the * button which I use on all 45 AF points and the other is the centre point (or 'selected focus point') button which I have permanently assigned to centre point, and with a custom function, set to focus when I press and hold it. So basically, I have a choice of whether I want to focus using all the AF points, letting the camera choose which, or just centre point only, simply by moving my thumb to each button. It's an incredibly useful feature to have and has completely eliminated sprackling with different AF points, and I now actually trust my camera's AF. I only need to recompose if what I am focussing on is outwith the focussing elipse.

One tiny niggle of the 1Ds is that all the focus points are clumped in the middle. I don't know if Nikon's system has them more spread out though, if I remember the 7D I tried had them a little more spread out.

 

[CT]

I'd heard a lot about it too... then I saw what one of the MotoGP media togs had done with his last weekend... stunning (when coupled with many thousands of pounds of long prime) BUT by his own admission not as good as a D3... (IQ this is not, necessarily ISO - it was a blazing hot weekend). Colour rendition looked a bit out on the red (Ducati) bike of his shot too, but it was a stunning image none the less straight off the camera. So 7D is perfectly capable.

There's no doubt you've a very valid point there Kemo Sabe- the 7D performs it's best coupled to top end glass without a doubt.

I shoot at 800 ISO most of the time and don't think twice about using 1600 ISO, but I think it's generally accepted now by most people that the high ISO performance is good. The thing which completely mystifies me is that the word on the street now is that the low ISO performance is pants. I've taken numerous shots in various light at 100 ISO and simply can't see a problem.

 

[kaz10]

I tend to use centre for my bird photography unless I haven t much room and want for instance a portrait shot then i will move wherever i want it then and then use the custom functions you can set for my flight shots using some or all the points

 

[mrtoad]

my first port of call is a spot reading on the subject
this entails centreing the camera on that area..
if it isnt too far from the main point of focus...and i am usually using wide angle in daylight
it doesnt present a problem
if there is a greater variation then i load in the settings on manual or use the +/- exposure part on the camera to achieve the desired exposure when recomposed

a lot of hassle but i cant think of anything more useful

on a long focal setting i will defo use manual exposure settings and set the camera to manual focus...

 

[desantnik]

The thing which completely mystifies me is that the word on the street now is that the low ISO performance is pants. I've taken numerous shots in various light at 100 ISO and simply can't see a problem.

Hmmm what about if you look at blue skies - the D300 has a fair amount of colour noise at ISO200 if you pixel peep at blue skies.

Can't say it bothers me at all mind you!

 

[LongLensPhotography]

For me it is usually centre-point AF and recompose as it works great for me, even at f/1.8! 1Ds mk2 works a treat with all AF points, but 40D can be hardly trusted with the centre one. 40D works well enough with 17-85mm f/5.6 for most amateurs and this is all Canon had intended. I was considering Nikon but as I have 1-series now that would be completely pointless waste of money.

P.S. Noise is a thing of a past with Lightroom 3.

 

[cowasaki]

A vote for using both techniques.

 

[CT]

Hmmm what about if you look at blue skies - the D300 has a fair amount of colour noise at ISO200 if you pixel peep at blue skies.

Can't say it bothers me at all mind you!

Can't say I've noticed any, I'll have to do some tests.

 

[redhed17]

I've always used the nearest focus point to where I want to focus. That's what the they are there for after all.

As has been pointed out, using the central focus and recomposing may knock the focus off, especially at wider apertures.

Yes there are different types of focus points with the cross type being better, but the normal vertical focus points should be good enough most of the time (imho) especially if the subject is still and in good light as in a studio environment.

Focus point coverage. The D300(S) may have the same focus system and number of focus points as the D700/D3(S)/D3X but the coverage of the focus points in latter cameras is smaller across the frame, and I think that is the same for most 'full frame' cameras compared to the APS-C sized sensor cameras. Possibly forcing the user to keep their subjects more central. :shrug:

 

[menthel]

Dean , if you want to swap to Nikon, just do it! You are cluttering up the forum with all of these threads trying to make excuses to yourself why its a good idea!

 

[trencheel303]

Focus point coverage. The D300(S) may have the same focus system and number of focus points as the D700/D3(S)/D3X but the coverage of the focus points in latter cameras is smaller across the frame, and I think that is the same for most 'full frame' cameras compared to the APS-C sized sensor cameras. Possibly forcing the user to keep their subjects more central. :shrug:

It's because as you say the focussing system is the same, but the sensor is bigger, meaning the focussing area in the VF appears to be smaller. As far as I know the same applies for canon's 1 series cameras, the 1D with its 1.3x crop factor will appear to have a larger focus area than the 1Ds, but since the 1D is designed for action shots, this isn't a bad thing!

I doubt it's anything to do with forcing the photographer to keep subjects central, it's just a side effect of the larger sensor decreasing the apparent size of the focus area.

 

[redhed17]

I doubt it's anything to do with forcing the photographer to keep subjects central, it's just a side effect of the larger sensor decreasing the apparent size of the focus area.

I know trencheel303 which is why I mentioned it.

Everyone was just saying that all the AF systems were the same and I was just pointing out the differences between Full Frame and APS-C AF systems using the same AF system.

I should have said 'A side effect is possibly forcing the user to keep their subjects more central'.

A major re-design would probably be needed to make FF AF coverage the same APS-C cameras, and that would cost lots of money if it was indeed possible. :shrug: Using the same AF system across many cameras is obviously a way to spread R&D costs and the APS-C sensors is where the AF needs to work/fit because that is where the volume is. The FF professional cameras will almost always have the cutting edge AF first though, before it filters down the ranges.

But thanks for pointing out my poor writing.

 

[buckas]

centre point and back button focusing

 

[trencheel303]

centre point and back button focusing

on a 7D why?

 

[Lensflare]

There seems to be a bit of confusion over how the 3d tracking works in the Nikon system.

51 3d tracking uses all 51 focal points live at any one time and chooses the one nearest to follow the focus (jumping from one focus point to the next as the subject moves around the frame) and information from the colour reading trickery and distance info (the D part of the lenses) to focus. it uses a lot of mathematics to do this, and so is slower than other focussing methods - but is very accurate.

By limiting the number of focus points chosen, from the 51, to 21 or even 9, you can speed the focus tracking, because you are limiting the sums the camera has to do with the more precise information delivered.

By selecting "9" does not mean you have lost the use of the other 42 focus points, far from it. All you have done is told the camera to concentrate on the 9 focus points SURROUNDING THE ONE YOU HAVE SELECTED - that is why it speeds the focus up. Lock-on is the same however many you select. So even with just 9 chosen, you can still use all 51, just not all at the same time...as you select your focus point the "zone of 9" moves around with you.

If you have no idea of where your subject is going to be within the viewfinder and require the focus to track the subject, once you have hit it with your chosen focus point, then use all 51 (which can also use 3D, but doesn't have to).

If you can keep your camera more or less pointed at where the subject is going (so, linear movement that you can more or less keep up with to have it close to the focus point you hit it with) you can reduce the time taken to do the maths, and so speed up the focus tracking ...choose either 21 or 9.

For my powerboats, bikes, cars etc...9 is fine, because I can more or less keep the selected focus point on the subject, I have some idea of where it is going and only need a little bit of leeway around my selected focus point. I don't need the entire frame of focus points "live" all the time - that is just wasting time and energy on the ones the opposite end to where my subject is.

I hope that helps a bit with your choices. I always choose my focus point for the subject. Rarely do I use focus and lock, because the plane of focus changes with the angle of your view, so as you tilt the camera, you move the plane of focus and your focussed distance is likely to not coincide with your subject.

Try this to see what I mean. Put a can of beans on a stool. Sit or lay down below the can of beans. Now focus and shoot using both methods and see how the zoneof focus moves quite dramatically in your frame due to the angle of view - at an angle like this magnifies the effect and so makes it easier to visualise and to actually see the difference.