Having some problems...

[djtyrrell]

I am having some problems with the focusing or depth of field or something that is affecting the quality of my pics. Spot in the centre is perfectly in focus and then even a couple of inches out of the centre will be out of focus, im only being picky because i don't want to leave my camera on auto all the time want to learn how to use it properly. Here is an example pic...

If you look at the control button it is already out of focus ...its starting to get annoying lol any help cheers

Stu

 

[Torus34]

Your photograph shows the result [perfectly normal, by the way] of using a large lens opening. The depth of field range becomes very narrow. If you choose a camera setting which will result in a smaller lens opening [bigger f number], the depth of field will widen.

A simple discussion of the relationship between f stop, shutter speed and DOF can be found at

http://www.thephotoforum.com/node/36

While the article is aimed at the film camera user, the relationship is true of all cameras which have adjustable lenses and shutters.

 

[djtyrrell]

so is it just the fact that i have a wider lense on it? or is it so to say just not helping? Cheers

stu

 

[fmw]

so is it just the fact that i have a wider lense on it? or is it so to say just not helping? Cheers

stu

No, you need to study up on depth of field. The lens focuses on a single plane. How much is or is not in "acceptable" focus beyond or in front of that plane of focus depends on the aperture, the subject to camera distance and the focal length of the lens. Torus was saying that, if you stop down the lens to a smaller aperture, more keys will come into acceptable focus. If you stop down enough, the whole keyboard will look sharp. Why not spend some time reading up on depth of field. TPF has many posts on the subject. Search away.

 

[djtyrrell]

arr right i get it now (sorry bit slow 2day) ok thanks guys i will have a play and see what i can do! Cheers

Stu

 

[The_Traveler]

TO add to other excellent responses

A classic exercise is to set the camera on a tripod (or in a fixed position on a flat surface) with a row of dominos extending away from the lens. Focus (manually) somewhere midway along the row and then take a set of pictures at different f stops.

You can clearly see the effects of f stop on dof.
The effects of the f stop are more pronounced the closer the point of actual focus is to the lens.

 

[djtyrrell]

oh that is a great tip, i am going into town today to pick up a tripod so i will give it a go and come back tonight with some results!! thanks all again!

Stu