[Schellamo]

Does anyone here use it? I've just discovered it not long ago, and now I feel like I've mastered it, I absolutely LOVE it!

My focus and exposure have been totally spot on using this technique...



I've been totally chuffed with it, and it makes for a lot less post processing too!

[smarti77]

I'm not familiar with the term "back button focusing". Can you explain the method?

You're right though, the exposure for skin tones on these looks great. The focus on the eyes also stands out. Have you done much post processing on these?

[Paul.R.Lindqvist]

Its means you have one button to engage the af, the shutter just activate the metering.
On nikon its called "af on" button. Its useful if you want to focus and then recompose, just push the af button and then recompose and press the shutter.(since the shutter wont engage the af) Or if u want to meter (spot) diffrently from the af brackets.


/Paul L.

[Schellamo]

On my camera (canon 350D) you have to change it in the menu to back button focusing (although, I don't know what its actually called...) For me, it means that I can push the shutter half way to get my exposure reading (so I point it at something that's about 50% gray- in this instance the grass) then recompose press the back button to focus, then release and if I want I can recompose again and press the shutter down all the way to take the shot. It sounds complicated, but once you've had a little bit of practice its easy and just as quick.
I find it good, because I usually press the shutter half way down, then wait for the right 'moment' but I find it annoying on my 50mm because it is always 'searching' for focus (the whole time I have my finger on the shutter). This way I can set the focus and then wait for the moment without it 'searching' or changing the focus while my finger is pressing the shutter half way.

I hope that makes sense.

These shots have minimal post processing, a little sharpening and colour boost is all.

[smarti77]

Funny how different brands have different names for the same thing. I often try the method described but wonder if I'm metering on the right object (I wouldn't have thought grass would be a good 'grey point'). If I bought a professional 'grey card' would this give me the right exposure every time???

[Paul.R.Lindqvist]

If you use a grey card it will give you a right exposer for a subject that is neutral grey. (given you have the light falling onto it, as the camera see it.

Usually i just spot meter on the subject to ensure i get the right exposure on the subject. Metering of the grass just ensures that the grass will rendered as if it was neutral grey. As for being a good grey point or not depends on how hot it been i guess. LOL



/Paul L.

[shuttertalk]

Interesting topic Schell...

I came across this function a while back but dismissed it because I'm used to the old compose, half press and then full press to shoot. But I guess it sort of makes sense because AF and metering are 2 separate functions and sometimes you want them to be independent of each other...

Maybe I'll try using it - might get some taking used to though...

[NT73]

On my 350D you can lock the Aperture by 1/2 pressing the shutter, and then while holding the shutter, press the lefthand button (of the two) at the right hand side at the top/back (the demagnify one) and then you can let go of the shutter and recompose and just focus.
( Aw shucks)
Where is this other button?

I'm going to look through the manual.:/

[Wedding Shooter]

That second shot is lovely - very nice isolation of the subject.

[Schellamo]

NT, now you've gone and got me all confuzzled!

I think the reason I like it is because it stops the 50mm from 'searching' which it is prone to do sometimes (and drives me mad) so I get more accurate focusing. Especially when you take into account what Paul said about not needing to meter off anything but the faces (it was a lovely overcast day, so I think that's why this worked anyway) and of course a gray card would be better than grass, but I don't have one, and don't plan on getting one.

[NT73]

Locking the shutter and metering when the shot is taken, is probably better than vice versa as the light can change in seconds, whereas the subject doesn't normally move, unless its a train or plane or bus or...
in which case you would want to lock the metering and focus on shooting.

Ah well horses for courses, as they say. Nice to be able to do both.

I used a focus lock button on the panasonic most of the time, and your babies are pretty. All babies are pretty till nappy changing time.

[Banded Drake]

I know the 20 d has the same feature but i dont use it . I have been focusing manully ( with the new camera ) so i can focus on what i want . By holding the shutter button half down and watching the focus points ( i think the XT has 7 points and the 20 D has 9 ) . I always try to stay with eyes in portraits , is this kind of the same approach ? just not in auto focus?

BTW , my film camera has " eye control " which would follow your eye at 3 different points , i do miss this with my 20 d

....... Shawn

[NT73]

I would imagine that is correct Shawn. We focus automatically using the focus lights, and then lock it, by pressing the button. Then you can let go of all the buttons and shutter button. Recompose, and 1/2 press then just gives you metering for the light, it doesn't refocus. Good eh.
That set up is programmed in the menu. (somewhere in the parameter settings.... #4. I think on the 350D)
But if you use manual focusing you don't need it.

[Banded Drake]

I think i saw that in my book , but there are so many things to learn about it ( the camera ) that ill just stick with the way i have been doing it LOL . But it is good to know that i can do the same thing in auto focus .

Thanks ....... Shawn

[Schellamo]

NT, good point. In this case, I had a good overcast sky, so the light wasn't changing on me. I'm used to running around after a toddler who moves much faster than a train or bus or plane, I swear!!

[Paul.R.Lindqvist]

yup kids moves alot faster then the light usually change.

/Paul L.

[Wedding Shooter]

LOL - Kids are like greased lightning

[Kombisaurus]

I had a bit of a play with the "back button focussing" particularly with sports shooting in mind. And it works very well.

For the most part, continuous AF is preferred for sports shooting so the camera will adjust focus automatically to track the subject. This is fine while you are shooting the action and have a clear view of it. But its frustrating when somebody walks in front of you or you lose sight of the subject or something else happens which causes the camera to go hunting for focus losing you valuable time. Using the back button focussing; you can simply see the obstruction coming into view through the viewfinder and release the back button as it passes through the current AF point. The camera maintains its current focus point and when you press the button again picks it straight back up without the need to hunt. Many of the expensive Canon L telephoto lenses have buttons built into them for just this purpose.
The second problem of continuous AF is that you cannot focus and recompose at all - the camera simply re-focuses as you recompose. While shooting sports, I often see something stationary worth shooting (official, crowd, building, etc) and want to compose it away from the selected AF point. This isn't as much of a problem with the 30D (with its joystick to select the AF point quickly), but it was really annoying on the 350D. The back button focus trick also works great to eliminate this problem too.

But in the end I went back to the old way of shooting. I'm still really tempted to give it another go because once mastered I can see it would be very useful, but I didn't find it all that intuitive to shoot like that. I love the idea of it though.

And finally, something to ponder... think of the times when you hand your camera to a non-photographic friend to take a shot of you... it will confuse them a LOT.

BD brings up an interesting topic when he mentions he focusses manually. Manual focus is often overlooked with digital.. and there is some good reason for that with the smaller viewfinders making it more difficult to see when things are sharp. But its a great help that the (Canon) AF points light up when they get focus, even when manually focussing. This alone can make MF surprisingly handy. I'm sure other manufacturers do the same thing too.