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Are you a singly focused individual?


Carabosse 18 41.5k 270 England
8 Jun 2011 6:44PM
When autofocus cameras first began - on 35mm film compacts - it was customary to have a single AF point... positioned at the centre of the viewfinder image.

Over the years the number of AF points has expanded and even compacts have the number of AF points in double digits. I have gone along with this over the years without a great deal of thought, I must admit. But the acquisition of a Micro 4/3 camera has caused me to look again at the issue of using AF points, because the AF system is different from that in a DSLR. I am now experimenting with, once again, a single centred AF point both in the M4/3 camera and the compact . And I feel all the better for it! Grin

Does anyone else feel accuracy can be better using a single AF point? And why exactly do we need a large number of AF points?
8 Jun 2011 7:03PM
I've always used the central, single AF point then half pressed the shutter button and recomposed if necessary. The alternative is to let the camera do it (which may not always work with the image you have in mind) or press the AF point button, choose your AF point, set it then shoot. By this time the perfect image may have gone. I'm used to my way, it nearly always works, its faster and I believe the central AF point allows a more precise focus.
darranl 11 318 England
8 Jun 2011 7:08PM
I find it useful to use the other points either when on a tripod or if using continuous auto focus.
Gaucho 19 2.8k 2 United Kingdom
8 Jun 2011 7:18PM
90% of the time I use single focus. As chrelen says it's the more accurate focus point and in any case, after a lifetime of using film cameras with split screen, manual focussing, I'm much more comfortable with it.
Malcolm
mikehit 11 8.0k 13 United Kingdom
8 Jun 2011 8:16PM
Single point for me, too. I am starting experiment again with the 'zone' focussing when shooting birds in flight but that is the only time.

In what way is the M4/3 focussing different to a DLSR?
User_Removed 17 17.9k 8 Norway
8 Jun 2011 8:24PM
Single point - and re-compose for most of my stuff.
Carabosse 18 41.5k 270 England
8 Jun 2011 8:27PM

Quote:In what way is the M4/3 focussing different to a DLSR?


It uses contrast detect rather than phase detect.

Interesting that people finding greater accuracy most of the time with single-point AF. I agree that for 'grab shots' of whatever sort, multi-point could be better... but even then I'm not 100% sure.
strawman 17 22.2k 16 United Kingdom
8 Jun 2011 11:18PM
I tend to pick a single point, but it is not always the same one, so I want centre of the frame, and then ones positioned on the thirds. For things in motion it can help to have a cluster of AF points around the main ones so you can still track if you have not kept the AF point correctly centred, so the AF locks on a point then follows the subject. With multi-point it can be a problem of what catches the Af systems fancy, normally the closest point of high contrast.

Re contrast of phase type I think with fast response situations the phase system has an advantage as it can (within a reasonable range) calculate how out of focus and in which direction the lens is miss-focused, while a contrast system has to move the lens to look for direction information and then it can struggle to work out how far out of focus it is so it tends to focus in an iterative manner (or more so). But on static subjects it is far more likely to get it precisely correct.

With SLRs do you not find yourself doing a double half tap, where you half press the shutter for initial focus then another half press to be certain/optimise it. Or is that just me when working in single shot AF.

The system I would love to see is the hybrid one, where you use phase detection for way out of focus situations then switch to contrast for detailed focus. I have heard of camera sensors with phase detectors buried with the pixels. In fact the SLT devices from Sony have the potential to have hybrid focusing, but so far they have not implemented it. Perhaps the A77 (if it ever gets to market) will have it. Suddenly SLT would have a killer feature. I guess the problem is the processing power required.
keith selmes 17 7.4k 1 United Kingdom
9 Jun 2011 12:01AM
Using an M4/3 camera with those low cost high quality vintage lenses - they're all manual you know Wink

With AF I just thought mult focus points were a complication I didn't need to learn about.
Carabosse 18 41.5k 270 England
9 Jun 2011 12:05AM

Quote:Using an M4/3 camera with those low cost high quality vintage lenses - they're all manual you know


I've been practising with MF on the M4/3 using "focus assist". Haven't yet decided whether it actually does assist, or is just a nuisance. Lol! Wink
ade_mcfade 17 15.2k 216 England
9 Jun 2011 12:10AM
I usually just do teh centre spot AF

was doing some 1-2-1 tuition yesterday and he kept getting the wrong things in focus.... then realised he'd got all 9 focus points active and it was picking the wrong things. if you've got high contrast things in the background, the outer AF points usually find them Sad
cats_123 Plus
17 5.0k 30 Northern Ireland
9 Jun 2011 7:20AM
Have tended to shoot with `Dynamic' focus (3 points on my D60) but I really find the wheel control is in an awkward place (top, controlled by right thumb). It would be great if I had some left hand control!! Sad.

So I'm going to try out single point for a while Smile

This thread has also made me look at the Menu more closely, and I've even found where to set to B&W!!!!! (after all this time!!! Wink) so watch out in the B&W group !! Wink
franken Plus
18 5.2k 4 United Kingdom
9 Jun 2011 8:08AM
I only use a single af point on my Samsung compact. (centre spot)

I would say that I use single af on my Slr for about 90% of the time as well. (centre spot) I find the accuracy of focusing is in my hands and not what the camera thinks it should be.

Easy to focus on what you want to be sharp and then recompose. Or about a third into the scene.

I find that most of my images are sharp where they should be using this method.


Ken
Gaucho 19 2.8k 2 United Kingdom
9 Jun 2011 9:36AM
One other method I use on my D90, which some may be aware of, is setting the AEL/AFL button to Autofocus On and Aoutofocus Continuous. This means you can focus continuously as long as you press the button or focus release and recompose. Some call it back focus and though it takes some getting used to, it is very useful. Here is an explanation for Canon users.

Malcolm
BigRick 15 2.1k 3 United Kingdom
9 Jun 2011 9:55PM
about 99% of the time i use single point focus.... and move it around the frame depending on orientation of shooting or subject matter.

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