Focus problems found today, way to improve?

asiona1

Hi all,

Thanks heaps for all ideas towards my 12-24mm f4 lens, which I took with D90 today for St Patrick Parade.
It was pouring during the parade, luckily I have got some pre-show photos.
http://www.flickr.com/photos/119756785@N06/

I found one major problem in my photos: seems like the focus is background rather than the people.
ie. DSC_0038, 0042, 0074, 0128.
I used single focus point and I did move the single focus point among the 11 points in the viewfinder to suit the position of the subjects - people.


Is this a right way of doing it?
OR shall I just position central focus point on the subject + half way depress shutter to lock focus + twist camera to compose the frame?

Maybe the above question sounds stupid, but out of focus really annoys me.

Thanks heaps

Pistnbroke

if you are using single centre focus pint AF-S then you put the central point on the main point of interest (what you want in focus) half press to focus and then re frame your shot and hit the button. If the central point goes say between two people and focuses on the background then you have a shoot through as I call it and that sounds like what you have .

asiona1

if you are using single centre focus pint AF-S then you put the central point on the main point of interest (what you want in focus) half press to focus and then re frame your shot and hit the button. If the central point goes say between two people and focuses on the background then you have a shoot through as I call it and that sounds like what you have .

Is this the most common way of focusing or is this working well for non moving subject?
How about for landscape, is single center focus working well or other focus method works better.

ThanksPistnbroke

Msmoto

Focus techniques vary among photographers and the subject. For stationary objects, using one of the focus points in AF-S as described by Pistnbroke, recomposing is common. When there is motion the AF-C will allow the camera to continually refocus as the subject moves, but one must maintain the focus point exactly where one wants the sharp plane to be.

Practice is how we figure this out. For a parade, I would be using the AF-C, and moving my focus point all over in order to have the composition and proper focus as I desired.

Pistnbroke

I dont think thats quite right ..if you are in AF-C and 3d mode and you put the central focus point on an object the focus point will follow it where ever it moves ...But does a D90 have AF-C 3d ??

Paperman

It's really hard to miss focus on a 12-24mm lens - let's say in the ultrawide range at least. You should have 1m to infinity depth of field as long as your focus point is " NEARBY " and not at the far end. I never shoot other than single point AF and I would still do this for this kind of photography but if you are not good in following where your camera focuses then maybe you should switch to multipoint AF . The camera is mostly likely to pick up the nearest points making it hard to miss focus in wide angle.

asiona1

It's really hard to miss focus on a 12-24mm lens

1.It's really hard to miss focus on a 12-24mm lens
Do you mean this lens is easy to focus throughout the range?

2.You should have 1m to infinity depth of field as long as your focus point is " NEARBY " and not at the far end
Is Nearby meaning i need to focus on something in the foreground to get 1m to infinity in focus rather than focusing to the far distant because the later can blur the front or Middle of the field?

3.I never shoot other than single point AF
Do you shoot landscape with single point AF as well?

Thanks for all the info guys coz i just started using this lens, therefore would be a very steep learning curve.

Any recommdation of article or books regarding use of this lens?

Paperman

1. I did say " in the ultrawide range at least " . I based it on simple Depth of Field rules.If you play with a DOF calculator (online) at 12-18mm range for 2-3 meter distances, you will see how deep a focus area can be obtained.

2.Exactly . If you focused by mistake to infinity ( instead of a near subject ) in the case above, you would get less DOF and probably miss the focus on a subject 2 m away. You always have more DOF past your focus point ( towards infinity ) than between the focus point and the camera .You are "wasting" the DOF if you focus too far away.

3. I can say I only shoot landscapes and always use single point AF. The AF point is 95% of the time somewhere 3-5 meters from the camera or nearer ( assuming the frame starts from 2-3 meters from my feet and goes all the way to infinity ) . At f8, it provides enough focus between 1.5m to infinity.

asiona1

Thanks guys, these details are very useful.
I will try some more shots over the weekend to get more practice and probably more questions to come.

Plus, i m going to a camera club on Thursday night. Looks like i m quite serious now. haha

Vipmediastar_JZ

you can purchase a lens calibration tool if your camera has fine tuning or you can follow this tutorial to see if it helps. I will try this out later today too along with the datacolor lens align tool. If the problem persists contact nikon for evaluation of your photos.

NSXTypeR

Maybe I'm pixel peeping here, but I think I've been missing focus with my D7000.



It's true that I've only gotten my D7000 for 3-4 months by the time this photo is shot, but there are times when the AF is unreliable- it will get close to focusing, it will indicate that it has focused, but is clearly missing focus once you get back.

That being said, it is usually unreliable in darker conditions, such as when I took that shot of the Buggati above. Am I being too hard on my equipment, especially when I have a slow kit zoom?

In this case with the Buggati was with the 18-135, but I've also had issues with long distance focusing with the 105mm Macro AF-S VR.

Are there any D7000 owners that can give me pointers on this? Is this a user error issue or do I just don't know my camera well enough?

Any comments would be welcome on this, because the D7000 can clearly produce very sharp images, I'm just trying to see where I can make up for these issues.

There are so many variables to think about that my head is spinning.

spraynpray

@NSXTypeR: First, a question: Where did you focus on this shot? I only ask because the centre of the shot is on the middle of the bonnet and so there is no edge for the AF to use - I'm thinking you may have moved the focus point or focused and recomposed?

Anyway, I believe your shot is as sharp as it could have been and the apparent out of focus is the D7000's ISO noise. I have one and I know it's noise limitations very well. The exact same shot with a D7100 would have been crispy.

If you want to avoid that 'sh*t' moment when you get home and view shots large, instead of leaving your embedded jpeg settings at the factory or sharpened positions, actually back off the sharpness a little so you are more critical when chimping. That is all good unless you shoot jpeg, if you do, leave it at factory or better still click the sharpness up one. If you want a shock followed by some expense, borrow a D7100 and compare Hi ISO performance.

@Vipmediastar_JZ: asional doesn't need a lens alignment tool for a 12-24, he just need to learn DoF. You can be so relaxed when using an ultrawide that you can (and I often do) turn autofocus off and just use manual.

NSXTypeR

Honestly, I don't remember where I focused- I took this photo over a year ago. I'm pretty sure I left in in AF-S, and used the center AF point. I'm sorry if that doesn't help, but I often sometimes missing AF for no reason at all.

I was wondering if there were tips you guys have on better AF practice or AF settings you guys use on a D7000.

Thanks again!

WestEndBoy

@Vipmediastar_JZ: asional doesn't need a lens alignment tool for a 12-24, he just need to learn DoF. You can be so relaxed when using an ultrawide that you can (and I often do) turn autofocus off and just use manual.

Thus my two wide angle manual focus lenses. I don't miss auto-focus at all. However, the 50mm 1.2 starts to get tricky when I shoot it below f/2.8.