Focus lock and recomposition?

badboy1984

badboy1984

Messages
2,529
Edit My Images
No
I'm currently using a Nikon DSLR system and was wondering who uses focus lock recomposition instead of selecting the AF point on the view finder?

Reason i ask is i use to select the focus point manually myself and recently i start using focus recomposition because one of my lens doesn't focus well on dark subject so it force me to focus the brightest spot on the subject and then move my camera around for the composition i want.

Do we all use this method to fast focus then move the camera around? Select AF point can be pain sometimes .....
 
My son uses Nikon I use Canon, all my life I have focussed and re composed from Film to DSLR.

I and he only use the centre focus point anyway, when you have focused you leave the finger on the release and re compse and click, done.

Couldn't be easier !
 
I'm the same as JSER. I couldn't be bothered with fiddling around with the AF point before shooting.
 
Same as above but with BBF, 'shutter' button for exposure, handy for spot metering. Control is everything ;)
 
roseway said:
I'm the same as JSER. I couldn't be bothered with fiddling around with the AF point before shooting.
Click to expand...

The only one I enjoyed using was my Canon EOS30E, eye controlled focus, that was good, but I have grown up on split image, to me still the best, and one central point is best to me.
 
I program one button for focus lock, and another for exposure lock. It's a bit three fingered, but when you get the hang of it, you have a lot of control, and it is as quick as you like

I use a single focus point, and generally spot metering
 
Richard King said:
I program one button for focus lock, and another for exposure lock. It's a bit three fingered, but when you get the hang of it, you have a lot of control, and it is as quick as you like

I use a single focus point, and generally spot metering
Click to expand...

Surely your focus is locked with a finger kept on the release, all you then have to do is move and re compose, is that not easier, I have never used the focus lock.
 
it is more to do with separating the focusing from the shooting... my way, there is no chance I will squeeze the trigger too hard. That suits the way I shoot - sometimes I compose and meter 30 seconds before I shoot
 
Richard King said:
it is more to do with separating the focusing from the shooting... my way, there is no chance I will squeeze the trigger too hard. That suits the way I shoot - sometimes I compose and meter 30 seconds before I shoot
Click to expand...

Ah I see, so no real difference just as we are all different, there are different ways.
 
JSER said:
Ah I see, so no real difference just as we are all different, there are different ways.
Click to expand...

Yep. Its a fling back from the manual focus days, when you metered, focused, composed, shot
 
Is good to Know lots of *** use thus method instead of selecting focus point. It make life my easier, worry *** composition rather than select point then miss the shot.

Cos my lens doesn't hunt well at very dark or extreme poor lighting so centre focus then recompose will help me alot since the illumination light on the Nikon camera only work on centre focus.
 
I don't know about the D7000 (the OP's camera), but my D70's focus points behave differently to each other. The central one responds to both horizontals and verticals and works better in low light, whereas the outer points only have horizontal or vertical detectors.

Something to bear in mind.
 
Another method I've used occasionally is to half press the button to focus, then release it and flick the AF/MF switch on the lens to manual focus. After that you can take as many shots as you like without the focus point changing.
 
roseway said:
Another method I've used occasionally is to half press the button to focus, then release it and flick the AF/MF switch on the lens to manual focus. After that you can take as many shots as you like without the focus point changing.
Click to expand...

A nice way to get soft images!
 
roseway said:
Another method I've used occasionally is to half press the button to focus, then release it and flick the AF/MF switch on the lens to manual focus. After that you can take as many shots as you like without the focus point changing.
Click to expand...

I think you need to read your camera's manual for the focus lock button :)

I use back button focus. This separates exposure from the focus and allows you to lock focus very easily whilst continuingto shoot.
 
duttytd said:
A nice way to get soft images!
Click to expand...

Nonsense. I've only used this method occasionally (with a camera which didn't have a focus lock button). Using centre spot focus, I focused accurately on the point I wanted to be the centre of focus, then flicked the AF/MF switch to ensure that the lens stayed focused on that distance. The camera was on a tripod at the time. It worked very well, and the images were properly in focus, exactly as I wanted.
 
roseway said:
Nonsense. I've only used this method occasionally (with a camera which didn't have a focus lock button). Using centre spot focus, I focused accurately on the point I wanted to be the centre of focus, then flicked the AF/MF switch to ensure that the lens stayed focused on that distance. The camera was on a tripod at the time. It worked very well, and the images were properly in focus, exactly as I wanted.
Click to expand...

Ah, you didn't mention the key word before that's why! TRIPOD
 
I am so glad I came across this thread. I spent the majority of last night reading my camera manual, which imho is terribly written. In any event I came across two sections that have me a little perplexed (thats quite easy).

1. Focus Lock
2. Exposure Lock

The thing that has me confused is whilst I know which buttons to press, there is no explanation as to why I might want to use these, in what circumstances etc.

I was planning to do some research during my lunch break today, but having come across this thread this morning thought I would just ask in here :)
 
Never used then amd never will.

If you depress the shutter button half way the camera focuses and meter reads, keep you finger half way locks both , you can then re compose the shot and press it all the way to take the picture.

Focus/meter lock "locks" both for a set time allowing you to do the same, what is so hard about keeping your finger on the shutter release baffles me, though I have grown up in the age of film and this is how we always did it.
 
lemonsprig said:
I am so glad I came across this thread. I spent the majority of last night reading my camera manual, which imho is terribly written. In any event I came across two sections that have me a little perplexed (thats quite easy).

1. Focus Lock
2. Exposure Lock

The thing that has me confused is whilst I know which buttons to press, there is no explanation as to why I might want to use these, in what circumstances etc.

I was planning to do some research during my lunch break today, but having come across this thread this morning thought I would just ask in here :)
Click to expand...
consider me shooting a bride and groom in the corner of a frame, outdoors. To the left is a big white building in the sun, the B&G are in the shade under a tree with leaves flicking about in front of them

If I expose for the brides face, then focus on her eyes, and reframe, I get a perfectly exposed and sharp shot (i.e. what I want to be is exposed properly, and sharp. The building to my left will probably be blown, but the black singe on it saying where they were, will be exposed OK

Here is what could of happened - Auto on the fly focus - might have caught a leaf in-front of the couple, not the couple itself. The metering might have taken to account the whole scene, and underexposed the man subject. If I was on spot metering, I might have caught a really dark bit of bark in the middle of the frame, metered that and over exposed everything

Essentially but selectively choosing what to meter from, and what to focus on, you make sure that the subject is in focus & exposed correctly. The problem with modern cameras is that the AF systems are now so good at responding to what is the closest that that flicking branch is very likley to be the thing it chose to focus on

Another thing (especially noticeable when shooting couples) is that often bang in the middle of a frame (another common metering / focus point) is often actually behind the couple
 
roseway said:
Another method I've used occasionally is to half press the button to focus, then release it and flick the AF/MF switch on the lens to manual focus. After that you can take as many shots as you like without the focus point changing.
Click to expand...

Yup - I do this too....
But there is one important caveat.
If you change the focal length on a zoom lens, then you need to refocus.

On my long lens I now use back-button focussing, well worth the hassle of learning.
 
JSER said:
Surely your focus is locked with a finger kept on the release, all you then have to do is move and re compose, is that not easier, I have never used the focus lock.
Click to expand...

Richard King said:
it is more to do with separating the focusing from the shooting... my way, there is no chance I will squeeze the trigger too hard. That suits the way I shoot - sometimes I compose and meter 30 seconds before I shoot
Click to expand...

Richard King said:
consider me shooting a bride and groom in the corner of a frame, outdoors. To the left is a big white building in the sun, the B&G are in the shade under a tree with leaves flicking about in front of them

If I expose for the brides face, then focus on her eyes, and reframe, I get a perfectly exposed and sharp shot (i.e. what I want to be is exposed properly, and sharp. The building to my left will probably be blown, but the black singe on it saying where they were, will be exposed OK

Here is what could of happened - Auto on the fly focus - might have caught a leaf in-front of the couple, not the couple itself. The metering might have taken to account the whole scene, and underexposed the man subject. If I was on spot metering, I might have caught a really dark bit of bark in the middle of the frame, metered that and over exposed everything

Essentially but selectively choosing what to meter from, and what to focus on, you make sure that the subject is in focus & exposed correctly. The problem with modern cameras is that the AF systems are now so good at responding to what is the closest that that flicking branch is very likley to be the thing it chose to focus on

Another thing (especially noticeable when shooting couples) is that often bang in the middle of a frame (another common metering / focus point) is often actually behind the couple
Click to expand...

if you're doing all that why not just switch focus off on the shutter button and use only the back button instead
 
Something that I am wondering here with focusing and recomposing. If you are shooting at very wide apertures, f/2.8 and f/1.4 for example, doesn't that affect the sharpness of the spot you are trying to focus? With the DOF being so thin at these apertures I wonder how you get around it.

Unless of course we are talking about shots that DOF are not so paper thin.
 
zulupentax said:
Something that I am wondering here with focusing and recomposing. If you are shooting at very wide apertures, f/2.8 and f/1.4 for example, doesn't that affect the sharpness of the spot you are trying to focus? With the DOF being so thin at these apertures I wonder how you get around it.

Unless of course we are talking about shots that DOF are not so paper thin.
Click to expand...

Practice, practice and a little bit more of the same. No matter how you focus you'll never nail a f1.4 full frame shot if your wobbling about all over the place.
 
JSER said:
Never used then amd never will.
Click to expand...

Potentially you are losing out

JSER said:
If you depress the shutter button half way the camera focuses and meter reads, keep you finger half way locks both , you can then re compose the shot and press it all the way to take the picture.
Click to expand...

If your subject moves, you will lose focus.
If the light on your subject changes your exposure will be wrong.

JSER said:
Focus/meter lock "locks" both for a set time allowing you to do the same, what is so hard about keeping your finger on the shutter release baffles me, though I have grown up in the age of film and this is how we always did it.
Click to expand...

The scenario's above are most often found when shooting something that moves and when you have click the shutter button that locks the focus - so if they move you need to refocus.

Lets say you use AI Servo. You can then half press the shutter and the focus will be tracked as your subject moves..... great you may think but the other issue is that as the subject moves so it is likely that the light falling on the subject will change.

When you half pressed the shutter it locked the exposure at that point. If the subject has moved from shade to open light and you take the shot, it will now be seriously over exposed.

This is why splitting the exposure and focus buttons makes sense.

If that is not how you shoot then fine you've no worries :)

Landscape photographer's for instance probably wouldn't need to use this. But wedding togs, sports togs etc can find this very useful.
 
boyfalldown said:
OK - the other posts were a bit confused. But why do you need focus lock then? Just take your finger of the back button and it stops AF - effectively locking it
Click to expand...

You don't really need focus lock if you use back button for focusing. As you say you just focus and take your thumb off the back buton. :)
 
zulupentax said:
Something that I am wondering here with focusing and recomposing. If you are shooting at very wide apertures, f/2.8 and f/1.4 for example, doesn't that affect the sharpness of the spot you are trying to focus? With the DOF being so thin at these apertures I wonder how you get around it.

Unless of course we are talking about shots that DOF are not so paper thin.
Click to expand...


Better then to use the appropriate focus point.

In situations like this focus, recompose doesn't work so well.
 
Alan Clogwyn said:
Practice, practice and a little bit more of the same. No matter how you focus you'll never nail a f1.4 full frame shot if your wobbling about all over the place.
Click to expand...

You are missing the point completely. Either you didn't read my comment in its entirety or you definitely do not really know what you are talking about.
Who mentioned about wobbling all over the place?
Please read again what I mentioned. It has to do with the DOF being paper thin at f/1.4 or even f/1.2 and focus and recomposing.

In this case Jim was the one who actually have given me an insight on it more on the exact issue I was wondering.
Thanks for that Jim, it makes more sense to me too. I had always wondered how on earth at such apertures one would focus and recompose. So I am not alone in thinking also that focus point in these circumstances is the only way to go

EOS_JD said:
Better then to use the appropriate focus point.

In situations like this focus, recompose doesn't work so well.
Click to expand...
 
zulupentax said:
You are missing the point completely. Either you didn't read my comment in its entirety or you definitely do not really know what you are talking about.
Who mentioned about wobbling all over the place?
Please read again what I mentioned. It has to do with the DOF being paper thin at f/1.4 or even f/1.2 and focus and recomposing.

In this case Jim was the one who actually have given me an insight on it more on the exact issue I was wondering.
Thanks for that Jim, it makes more sense to me too. I had always wondered how on earth at such apertures one would focus and recompose. So I am not alone in thinking also that focus point in these circumstances is the only way to go
Click to expand...


Alan makes a great point though Amin

Whilst you may think your hand is steady, in reality your hands and body move quite a lot - I think that is what he was referring to. So that can also indeed have a significant affect on the focus - When using very large apertures especally at higher magnification, you need to be VERY steady.

Manual focus may in fact be a better option in some cases too.
 
@Richard King - Thanks for the detailed response with example. It really helps me to understand why I might want to use this ( I think ).
 
Last edited:
lemonsprig said:
@Richard King - Thanks for the detailed response with example. It really helps me to understand why I might want to use this ( I think ).

So if I understand correclty and using your example the process would be somthing like this.

1. Zoom on the brides face and then lock the exposure
2. Focus on the eyes and lock the focus
3. Zoom out to recompose the entire shot to get the building and everything else in.
4. Take the photo
Click to expand...

Zoom out after you have locked the focus and if you then take the shot trust me, you will be way out of focus.

But hey, I am can't claim to be an experienced tog so please take this with a pinch of salt. I may be way wrong. I am just a newbie after all :)
 
zulupentax said:
Zoom out after you have locked the focus and if you then take the shot trust me, you will be way out of focus.

But hey, I am can't claim to be an experienced tog so please take this with a pinch of salt. I may be way wrong. I am just a newbie after all :)
Click to expand...

OK
this is all to do with geometry and optics

You are potentially confusing mixing 2 issues

- Off axis aberrations
- Curvature of field

Off axis Aberrations - How LCA, TCA, Pincusion/Barrel distortions, Coma are handled off axis, and rear their ugly heads in images are in essence the difference between good and bad lenses, but have nothing to do with the plane that is in focus

When you focus and recompose whilst the angle between you and the subject changes the distance between you and the subject, generally changes minutely. So to all intents and purposes the subject will still be at the same distance from the lens, and thus still in focus

However, what might happen, if the lens designer corrected heavily for a flat subject field, and chose harsh aspheric elements to do this that when you recompose, the subject will be out of focus. Its an easy thing to visualise... on a piece of paper draw a semi circle of say radius 10cm - that represents say 10M away. The centre of the circle represents the lens in your camera. Draw a line at a tangent to the circle - where the line touches the circle it is 10M away, as you move down the line away from where it touches, it is further away

The line represents a lens that is flat field focusing, the circle represents a lens that is focussing at a set distance from the lens i.e. a curved field

Remember the sensor is flat. Its pretty obvious that if you stood 1M from a subject, and focussed on it, and then moved the subject 20 M to the left it would be more than 1M away. Lens designers have the compromise on this pretty good now

However in the real world, with most modern lenses, if you moderately focus and re-compose, you will be well within the limits of the lens, and the image will be sharp

There is another option for the photographer too
- focus
- exposure
- compose
- touch up the focus with the focussing ring
 
Mike.P said:
Depends on the lens.

A parfocal zoom will keep focus all through the range.
Click to expand...

I did say I was a newbie didn't I? And obviously you came to the rescue.
All I know is my 70-200 f/2.8 would throw my focus way out if I locked focus, zoomed and then took the shot.

Hmm parfocal, don't know what type of lens that is, will have to leave that for my next lesson. Thanks for the clarification by the way Mike. Obviously you know your stuff :),
 
Half press the shutter button to get a single point AF point, hit an hold the back button, remove trigger finger, recompose, press the shutter button all the way, job done.
 
Richard King said:
Its pretty obvious that if you stood 1M from a subject, and focussed on it, and then moved the subject 20 M to the left it would be more than 1M away.
Click to expand...

More like subject at 6ft away with a 70-200 f/2.8 on a 5D MKII.
Oh and locking focus on the left eye and then recomposing it so you centralise it on the right eye. Would you still get the sharp focus on the subject's left eye?
 
You must log in or register to reply here.
Back
Top