basic advice with a d300 on focusing please

evilonion

evilonion

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Dave Peacock
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i have recently upgraded to the d300 and its quite a big step up from using my sony a200.

One thing im finding issue with is focussing with the 2.8 lens i bought.

in low light i had to shoot at 2.8 and sometimes a bit above as light was pretty abysmal...
what i found to be an issue though is the focus point... i tried all different settings but say if i shot a person at a 45 degree angle from a distance, the shoulder or side of face would be in focus but the eyes wouldnt...

maybe 1 in 10 shots would have the correct focus point.

Wasnt an issue with my kit lens as the f number was high enough to keep everything in focus, but when shooting with a limited range what would your advice be?
i was considering manual focus but then to be able to see if an eye is in focus at a distance is pretty impossible for me...
 
It depends on what focus mode you're in and where the camera focused.

I would have use a single focus point on the eye if you're not using it already, and see if it is focussing where you expect it to. The LCD should show where the camera focussed when reviewing images, if the focus point(s) is on the eye and the eye is out of focus, then something is wrong.

If you're using the dynamic (I think) focus mode were multiple focus points are used. then the camera could be focussing on a part of the person which is closest.

Also make sure you're not on continuous focus as well. You never know. ;)
 
only have a D5000

but for static shots i choose AF-S and single focus point
the OK button chooses the centre focus point only.....HTH?
 
what lens are you using. the main thing is to focus on the eye, then if its not in focus the lens could be front or back focusing.

also try getting used to focusing with the rear af buton as you can leave it in afc mode all the time and still focus lock by simply removing you finger then the shutter button will just keep firing without adjusting focus untill you start pressing the af button again.
 
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It sounds like you are using auto focus point select. That will almost always choose the closest part of the subject ie the shoulder, and at f/2.8 there is not enough depth of field for the whole face to be sharp.

If that's what you're doing then there are a couple of options but I think the best one is to select centre-point AF and then use focus-recompose technique. That is, get focus on the area you want sharp - always the nearest eye in a portrait - and lock the focus there by holding first pressure on the shutter release. Then when you recompose the shot as you want it, the focus will stay on the eyes.

Have a look here to see how much depth of field you've got www.dofmaster.com You just need to input your camera (for the fomat), focal length, f/number and distance. Everything you ever wanted to know about depth of field is on that site (and quite a lot more that you maybe didn't ;) ).
 
HoppyUK said:
If that's what you're doing then there are a couple of options but I think the best one is to select centre-point AF and then use focus-recompose technique. That is, get focus on the area you want sharp - always the nearest eye in a portrait - and lock the focus there by holding first pressure on the shutter release. Then when you recompose the shot as you want it, the focus will stay on the eyes.
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Sorry to disagree, especially when the OP has not replied with the settings that were being used, and I know focus and re-compose has been discussed before, but if you have a large number of focus points spread out over the viewfinder why not use the focus point that is on the point of focus that you want? The plane of focus changes, sometimes significantly if the object in focus is at the edge of the frame, when you focus and re-compose, add to that a lens with a wide aperture like OP has, and it could be a recipe for OOF images.

I know you're very experienced Hoppy, and may get excellent results using focus and re-compose, but surely focussing across the the scene being viewed when having multiple focus points is one of the reasons to have so many focus points? :shrug: Another reason for so many focus points is to accurately track a moving subject of course.

Some people say use the central focus point because it is a more accurate 'cross' type focus points on many cameras. If a non 'cross' type doesn't focus accurately, then yes, used the cross type to see if it is any better, but the normal focus points can't be that bad most of the time, and you should get to know the situations when 'cross' type focus points would be more beneficial to use.

The D300 has 15 'cross' type focus points out of the 51 points, so if the focus and re-compose is because of 'cross' type focus point, any of the central 15 focus could be used, hopefully a point that may be closer to the subject to minimise camera movement.
 
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redhed17 said:
Sorry to disagree, especially when the OP has not replied with the settings that were being used, and I know focus and re-compose has been discussed before, but if you have a large number of focus points spread out over the viewfinder why not use the focus point that is on the point of focus that you want? The plane of focus changes, sometimes significantly if the object in focus is at the edge of the frame, when you focus and re-compose, add to that a lens with a wide aperture like OP has, and it could be a recipe for OOF images.

I know you're very experienced Hoppy, and may get excellent results using focus and re-compose, but surely focussing across the the scene being viewed when having multiple focus points is one of the reasons to have so many focus points? :shrug: Another reason for so many focus points is to accurately track a moving subject of course.

Some people say use the central focus point because it is a more accurate 'cross' type focus points on many cameras. If a non 'cross' type doesn't focus accurately, then yes, used the cross type to see if it is any better, but the normal focus points can't be that bad most of the time, and you should get to know the situations when 'cross' type focus points would be more beneficial to use.

The D300 has 15 'cross' type focus points out of the 51 points, so if the focus and re-compose is because of 'cross' type focus point, and of the central 15 focus could be used, hopefully a point that may be closer to the subject to minimise camera movement.
Click to expand...

Disagreeing is fine :) I said it was only what 'I think' would be best for the OP, without making it sound too confusing and adding an additional stage to the process that I think is unnecessary. I certainly wouldn't worry about it in this case, and here's why.

There is no danger of focus-recompose as I have described it shifting the focusing distance significantly - that really only happens when you are are shooting a real close up of a face at f/2 or something, and lower. From the OP's descripion he has several inches of DoF (shoulder to ear) which is not enough for the case in point but plenty to cover the one or two cms you might lose through focus-recompose error.

And the method you are describing is also focus-recompose, becasue whichever focus point you choose, none is likely to be exactly over the eye you need sharp, so there is still going to be an element of recompose about it.

However, I agree with all the comments you make. And I'm sure the OP will find that extra information useful :)
 
Thanks for the reply folks.
My settings varied as I tried things out.

The camera was in mode p as conditions changed a lot and I'm not fast enough to use m yet.
The focus used was 3d for some but this was tricky so I used auto and pointed the focus point at the persons face.

From a distance though the focus square covered most of the face.
Should I be using the bottom setting (spot focus?)

The other issue from a distance was when I pointed the focus at the hands. The square covered the whole hand but the wrist was in focus not the fingers.
Almost every shot of the people holding hands has the fingers out of Focus and the wrist crisp focus.

I have arranged to photograph 3 people over the weekend and next week to help me get over this problem so any advice on what setting I should use would be great.

I will be using a sigma 18-50 2.8 when I shoot them (was using the nikon 70-200 2.8 with the problem).

Thanks for the link hoppy, although I'm not quite sure what to make of it? Using the guide it said I had a dof of around 60cm. Does that mean that from my focus point 60cm around that point should have been in focus? I've never quite understood how to work out those guides...

Sorry if this post is hard to read, I'm currently using my iPhone so I can't see what I've written :)
 
Just to add I've found the help fantastic so thankyou all for taking the time to write what you have :)

It's suprising just how much I have to learn moving to a better camera. The a200 didn't have half the focus options etc and I've never shot with such a wide apperture lens before.
 
Without knowing what your exact framing was, I can only guess at what the DoF might have been, but if it was a typical kind of general head and shoulders, I'd say probably around 10-15cm. Which is what I would guess at, and it also fits with your should-to-ear estimate.

This is the page you want http://www.dofmaster.com/dofjs.html On the left hand panel, input your camera at the top, then the focal length, f/number and shooting distance. All your depth of field calcs are then on the right.

Depth of field varies according to format, which is why you have to specifiy the camera, and then by f/number and magnification. F/number is straightforward enough, and the lower the f/number the less DoF you get. Magnification is the size of the subject in the frame, and that is estimated by inputting both the focal length and the focusing distance. The bigger the subject, the less DoF you get.

However, if you change lenses, say to the 18-50, but then move your shoting distance so that the subject is framed up the same in the viewfinder, then DoF will also be the same at a constant f/number because the magnification won't have changed.

Since you're having a practise run, try both using the centre AF point as I described, and then also selecting the closest focus point to the bit you want sharp, as Redhed suggested. Pick whichever method suits you, and the subject. I tend to use focus-recompose with the central AF point for almost everything, but I sometimes change to another AF point, and if I was shooting sport maybe with servo AF tracking a moving target, then I'd probably switch to auto AF point selection - it depends on the subject and the situation. And also just the way you like to work.
 
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I normally use the centre focus point and back button focus to decouple focus and exposure lock. It works well for me and I rarely go back to the default setting.
 
Ooh, I think I mentioned that. ;) :lol:

Seriously, glad you've got it sorted. It would be a right pain if you had a dodgy camera or lens. :thumbs:
 
Yeah thanks :) I didn't realise it was there.
I figured the continuous bit was to do with the 3d tracking etc.

Wasn't until I went to manual focus that I found the switch!
Typical :D
 
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