focus and recompose or set the focus point

LCPete

LCPete

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Which is best :)
I have been setting the focus points after framing the subject but beginning to think that its unnecessary
Talking about zoo photographs with 100 400 lens static subjects 10 to 30 feet away normally on f 5.6
Pete
 
LCPete said:
Which is best :)
I have been setting the focus points after framing the subject but beginning to think that its unnecessary
Talking about zoo photographs with 100 400 lens static subjects 10 to 30 feet away normally on f 5.6
Pete
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Focus-recompose using the centre AF point is only a problem with a) close subjects, such as a tight head shot from a couple of feet or so, b) when also using a very low f/number, like f/2 or less, and c) when the subject is well off-centre.

TBH I think the problem is exagerated. In the examples I've seen, and quite a few have been posted up here from time to time, it's much more likely to be subject movement or camera movement after focusing. It's very easy for that to drift by an inch or two without being noticed.
 
Thanks mate :)
I did try it today at the zoo on a cheetah cub that was facing me and managed to miss the focus but it probably was because I was leaning forwards trying to get the lens against the fence
 
I've been doing focus and recompose for years, since my bridge camera and it works well if you and they don't move.

I've recently started moving focus points, but this was when the camera was on a tripod locked in position, which made life a lot easier.

If you change focus points, it means you have to remember to reset the focus point to the middle or move it, so its something to remember rather than just focus and then recompose.
 
Thanks Dale :)
focus and recompose will make life easier its very fiddly changing the focus points on the 550D
I got into the habit of setting the focus point on my 40D, its very quick to nudge the joystick but have been struggling do do the same with the 550D so focus and recompose is the way to go:)
 
I think that the truth is that people look too closely at images on screen these days. Years ago you'd never notice if the focus was an inch (sorry, 2.5cm) out in even a largish print but these days people view at 100%+ on screen and complain about every little thing.

I'm pretty sure that focusing and recomposing could potentially throw focus out in a percentage of shots but if you can avoid pixel peeping I'm also pretty sure that no one will ever know :D
 
LCPete said:
Thanks Dale :)
focus and recompose will make life easier its very fiddly changing the focus points on the 550D
I got into the habit of setting the focus point on my 40D, its very quick to nudge the joystick but have been struggling do do the same with the 550D so focus and recompose is the way to go:)
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Mine is pretty easy to adjust, but it is also very easy to forget to set it back (even though it is a single button to reset to centre on the D3100).
 
Depends what i'm shooting. If i am going to be repeating the same sort of shot, lets say a motorsport event and panning the same way for a while, then i will change focus point.

If i am shooting a subject that is always moving and different style / orientation can be captured then centre and recompose.
 
I am going to ask a bit of a simple question but I have always framed a pic then adjusted the focus point then taken the pic.

I have read the term focus and recompose but am still struggling to get my head around what it actually is. Need someone to explain it in laymans terms to me!

From my understanding you use centre focus point, set up the focus to the object then move the camera to frame the pic then take the pic? Is this right?
 
ian-83 said:
From my understanding you use centre focus point, set up the focus to the object then move the camera to frame the pic then take the pic? Is this right?
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Yep, aim at object, button down halfway to focus and then re-aim.

Both methods work
 
I mainly Focus and recompose but have been thinking it may be better to use focus points.

I have a 50d and in the manual it states the center point is more accurate/sensitive than the other postions. How does this affect things?
 
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scottthehat said:
focus and recompose is bad practise and can cost you photos, try using narrow depth of field and you will see.
read this and it will save me explaining why.
http://visual-vacations.com/Photography/focus-recompose_sucks.htm
http://www.talkphotography.co.uk/forums/showthread.php?t=106421
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just read those links and it did make sense but does it apply for distances of say 30 feet away?

just found a depth of field calculator the depth of field at 30 feet is 0.45 ft at 350mm focal length and F5.6 so focus and recompose should be ok

but at a distance of 10 feet the depth of field is given as 0.05 ft not very much so I guess I would get problems with focus and recompose

but at that distance I would be more likely to be at a focal length about 150mm which increases the depth of field to 0.28ft
Just confused now ! :cuckoo:
but going back this week so will try both ways and see :D
 
I thought focal distance was in a curve, ie everything 6ft away was in focus, not that everything in a plane parrallel to the lens was in focus.

I will play with focus points more :)
 
Dale_d3100 said:
I thought focal distance was in a curve, ie everything 6ft away was in focus, not that everything in a plane parrallel to the lens was in focus.

I will play with focus points more :)
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No, it's on a flat plane. If you photograph as wall square on, it should all be sharp, even though the sides are further away. It's part of rectilinear lens design.
 
Couple of snaps to put some reality on this. Best I can do quickly is this mannequin perched on top of the telly. To make it easier to see, I stuck a ruler under her chin.

The head is about three-quarters life size, so this would be a very tight portrait in real life. Camera on tripod, 50mm lens at f/1.8 on a 5D2, distance 53cm (21in) from lens to the nearest eye, focused with centre AF point. On the ruler, sharpest focus is around the 24cm mark.

Second pic is recomposed to the left, and the focus has shifted back to 21cm, which because the ruler is at an angle, equates to less than 1.5cm of fore/aft focus shift away from the camera. DoF calculates at just over 1cm at f/1.8.

Focus on nearest eye
IMG_7414.jpg


Recomposed, the sharpest point has moved slightly under 1.5cm away from the camera (about 3cm on the ruler)
IMG_7415.jpg
 
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Great example Richard and I know the thread has moved on but you're working with slim margins with those specs.

The OP is talking about f5.6 @ 100-400m at fairly forgiving distances.
 
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dinners said:
Great example Richard and I know the thread has moved on but you're working with slim margins with those specs.

The OP is talking about f5.6 @ 100-400m at fairly forgiving distances.
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Yes, absolutely. My point is really that it's only a potential problem in extreme circumstances like this, whereas one of the links posted by TheHat suggests that it's rather more of a general focus-recompose problem (at least the way I read it).

I use focus-recompose with centre point all the time, and never have any issues, as I think most people do. I'm aware of it though, so would take care in a close portrait situation for example. I still say though, when your DoF is measured in mms, it is subject movement and camera movement that's likely to be the main problem.

Edit: Also, you'd never shoot a portrait like that with a 50mm lens (on FF) would you? That's crazy close, like under 2ft away. If you move back and do it properly with a longer lens like a 135 f/2, the angle of movement in recomposing is very substantially reduced to the point that the problem pretty much goes away, and if you're using a 70-200 2.8 zoom, well, it's virtually non-existant.
 
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I've always used the various focus points, working on the theory that they are there for a reason, so I've always used them.

Very interesting thread and one that perhaps proves that we sometimes get a wee bit too worried about certain technical aspects of photography.
 
HoppyUK said:
Yes, absolutely. My point is really that it's only a potential problem in extreme circumstances like this, whereas one of the links posted by TheHat suggests that it's rather more of a general focus-recompose problem (at least the way I read it).

I use focus-recompose with centre point all the time, and never have any issues, as I think most people do. I'm aware of it though, so would take care in a close portrait situation for example. I still say though, when your DoF is measured in mms, it is subject movement and camera movement that's likely to be the main problem.

Edit: Also, you'd never shoot a portrait like that with a 50mm lens (on FF) would you? That's crazy close, like under 2ft away. If you move back and do it properly with a longer lens like a 135 f/2, the angle of movement in recomposing is very substantially reduced to the point that the problem pretty much goes away, and if you're using a 70-200 2.8 zoom, well, it's virtually non-existant.
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Richard, would you use focus/recompose shooting wide open or close to with a fast prime? I shoot indoors a lot so I'm pretty close to my subjects.
 
i suppose richard has a point that at 400mm f5.6 at 30ft away on a 1.6x crop would give less margian for error, so you can get away with it more so as the dof would be 11.2cm(although still not a great dof)
50mm at f1.8 on a 1.6x crop at 5 feet away is 6.28cm and at 2 feet away 1cm
 
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The23rdman said:
Richard, would you use focus/recompose shooting wide open or close to with a fast prime? I shoot indoors a lot so I'm pretty close to my subjects.
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It's only a problem at very close range, with very shallow DoF - the combination of a big angle of movement, like maybe 30 degrees in that mannequin shot, and very small margin for error. With greater distance, that angle is dramatically reduced and DoF substatially increased so the problem hardly arises, if ever.

However, if you do find yourself in a very close/shallow DoF situation, you have a few options. Using an outer focus point is one, though in the second mannequin shot, not many cameras have an AF point that far out, in which case you could use the nearest point and then instead of recomposing in camera as you'd ideally like, leave the composition as it is and crop in post. Might have to move back a tad to allow some space around the subject to do that.

Or manual focus, with the subject framed just the way you want it. This is easy if you have a FF camera (they have bigger, brighter focusing screens) and have changed the standard screen for one optimised for manual focusing (they show the true shallow DoF better). If you have a regular crop camera, that's rather more difficult, but possible with a bit of practise.
 
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The only downside I've ever encountered to using the focus points further away from the centre is that (depending on the camera) they are often linear (as opposed to crossed). Linear focus points rely on having a target that has a good contrast line that runs perpendicular to the focus point so you need to be careful to select a good target.
 
Thanks for going to the trouble to show that Richard:clap:
It does show that at the sort of distances that I am working with focus/recompose should be OK
I am normally 10 to 30 feet away from big cats at the zoo in this case it was cheetah cubs:)
If I assume that the focus shift at worst case like your example changes the focus by 1.5cm and the depth of field is about 10cm I should be OK
I will never be below F5.6 unless I win the lottery and get the 400 F2.8:D
Pete
 
LCPete said:
Thanks for going to the trouble to show that Richard:clap:
It does show that at the sort of distances that I am working with focus/recompose should be OK
I am normally 10 to 30 feet away from big cats at the zoo in this case it was cheetah cubs:)
If I assume that the focus shift at worst case like your example changes the focus by 1.5cm and the depth of field is about 10cm I should be OK
I will never be below F5.6 unless I win the lottery and get the 400 F2.8:D
Pete
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You're welcome Pete, though I'm not sure you're getting the angle bit ;)

When you're close, like under two feet with the mannequin, you have to tilt the camera a lot to focus-recompose with the centre point if you want the subject towards the corner like that. Let's say it's 30 degrees in that example, which is probably pretty close, and at 2ft for the sake of round numbers.

If you move back to 4ft with a 2x longer lens for the same framing, that angle drops to 15 degrees. A longer lens again at 8ft and you're at 7.5 degrees. The focus recompose error is now within the zone of depth of field, even at f/1.8.

You're shooting at 10ft, and at f/5.6 - no problem at all and the focus-rempose shift would be down to a few mm, almost too small to measure and, even if it mattered, you'd have trouble focusing to that kind of accuracy. It's the difference between focusing on the eyeball or the eyelashes!

Compare that amount of error to how much either you or the subject is likely to move, and it's clear where the most likely problem is.
 
HoppyUK said:
You're welcome Pete, though I'm not sure you're getting the angle bit ;)

When you're close, like under two feet with the mannequin, you have to tilt the camera a lot to focus-recompose with the centre point if you want the subject towards the corner like that. Let's say it's 30 degrees in that example, which is probably pretty close, and at 2ft for the sake of round numbers.

If you move back to 4ft with a 2x longer lens for the same framing, that angle drops to 15 degrees. A longer lens again at 8ft and you're at 7.5 degrees. The focus recompose error is now within the zone of depth of field, even at f/1.8.

You're shooting at 10ft, and at f/5.6 - no problem at all and the focus-rempose shift would be down to a few mm, almost too small to measure and, even if it mattered, you'd have trouble focusing to that kind of accuracy. It's the difference between focusing on the eyeball or the eyelashes!

Compare that amount of error to how much either you or the subject is likely to move, and it's clear where the most likely problem is.
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Ahh see what you mean now Richard :D
I went out today to try both to see if I could see any difference but it was peeing down and the big cats did not want to come out
I now see that for what I do focus and recompose will be fine and a lot easier than messing about with the focus point:)
thanks Richard for your help and everyone else too:clap:
 
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HoppyUK said:
It's only a problem at very close range, with very shallow DoF - the combination of a big angle of movement, like maybe 30 degrees in that mannequin shot, and very small margin for error. With greater distance, that angle is dramatically reduced and DoF substatially increased so the problem hardly arises, if ever.

However, if you do find yourself in a very close/shallow DoF situation, you have a few options. Using an outer focus point is one, though in the second mannequin shot, not many cameras have an AF point that far out, in which case you could use the nearest point and then instead of recomposing in camera as you'd ideally like, leave the composition as it is and crop in post. Might have to move back a tad to allow some space around the subject to do that.

Or manual focus, with the subject framed just the way you want it. This is easy if you have a FF camera (they have bigger, brighter focusing screens) and have changed the standard screen for one optimised for manual focusing (they show the true shallow DoF better). If you have a regular crop camera, that's rather more difficult, but possible with a bit of practise.
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I have played around with manual focus, but I'm just not quick enough with kids to do it effectively. I asked because I always use the nearest focus point and then crop if necessary. I may have a bit of a play with recomposing again and see what happens in practice.
 
The23rdman said:
I have played around with manual focus, but I'm just not quick enough with kids to do it effectively. I asked because I always use the nearest focus point and then crop if necessary. I may have a bit of a play with recomposing again and see what happens in practice.
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There's no question that getting anything that moves sharp is very difficult when DoF is shallow. Probably the favouite technique for that is to forget focus-recompose and just pin the centre AF point on the subject and hope that servo focus will track it. You need both a good AF system and lens for that.

There's another technique that I've just remembered, and that is to use manual focus and continuous shooting mode. Then while the camera is firing, move the focusing ring slightly back and forth around where your best guess at sharp focus is. You should get one ot two keepers.
 
I tend to just use the four focus points that are closest to where the intersecting 'rule of third' lines are in the frame and with the joystick on my 30d set to select focus points so I can change between them quickly without taking my eye from the viewfinder.
 
don't think it's been mentioned, but I'm sure I've read that the centre AF point is the most accurate for metering.... in which case focus and recompose would give the most accurate metering?
 
andrew720 said:
I tend to just use the four focus points that are closest to where the intersecting 'rule of third' lines are in the frame and with the joystick on my 30d set to select focus points so I can change between them quickly without taking my eye from the viewfinder.
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thats what I used to do when I was using my 40D , cant do that on the 550D
I've been using focus and recompose for a couple of weeks now with no problems :clap:
 
benners said:
don't think it's been mentioned, but I'm sure I've read that the centre AF point is the most accurate for metering.... in which case focus and recompose would give the most accurate metering?
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I have noticed that with some extreme subjects like Red Pandas which have white faces and dark red and black bodies that the (evaluative) metering can change from shot to shot , not completely figured out whats going on but the exposure turns out OK when I focus on the face
I guess spot metering would be the answer
 
Works a treat heres some examples from last week:)
Especially pleased with the Meercat
it was quite close and was at 400mm at F5.6
I focussed on his eye and recomposed
I did try moving the focus point to his eye to see if the was any difference but he moved :D
It shows that I may have missed the shot without focus and recompose
These little guys dont sit still for long :D
IMG_4566.jpg

The Lioness was at 285mm at F5.6 bigger subject and further away, focussed on face and recomposed
IMG_4742.jpg

The Lioness again focus point pretty much central shot is slightly cropped but I cant see any difference in focus
IMG_4724.jpg

Cheetah cub quite a distance at 400mm and F5.6
IMG_4410.jpg

the origanals were sharper than they look uploaded think I need to sharpen again after resizing for the web
Thanks for your help everyone :)
 
usually use the focus and recompose technique for things that are moving to grab a shot quickly. Will have to have a play using the different focus points for things that are more stationary
 
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