Focus Point and DOF

  • Thread starter Thread starter RobbieW
  • Start date Start date
R

RobbieW

Guest
Hi,

When I take landscape photo's I struggle to get the whole image sharp and in focus. I know this partially comes down to my DOF settings, but when taking photos where you want the whole image to be sharp and in focus what do you focus on?

Hope this isn't too daft a question, I still prefer to use the auto focus points.

Thanks for any help and advice
 
Something about 1/3 of the way into the photo would be best if you dont want to go thru the whole hyperfocal distance discussion again. then you wont waste loads of focus.
 
Janice said:
Something about 1/3 of the way into the photo would be best if you dont want to go thru the whole hyperfocal distance discussion again. then you wont waste loads of focus.
Click to expand...

Thanks will try that,

I think I had better search for the hyperfocal distance discussion then cause its a big word and thats all I know about it
 
Things appertaining are here!
 
This is what you need to do (Tripod mount the camera manual focus and use a small F stop) you cant go wrong.
 
Yes but the point that you focus plays a part in how far back you get... so not losing any.

Just sticking it on a small aperture is a bit hit and miss ... depends where you focus.
 
The way I do it, firstly I use autofocus, but use my focus points individually to focus on a part of the scene roughly into 1/3 I want in focus.
The 350D has this function where you can chose one of the seven focus points individually.

Secondly I'll shoot at F22, meaning the depth of field is wide.

Most lenses have their 'sweet spot' at around f8 so you may lose a touch of quality shooting at f22, and of course your shutter speed will be slower, so a tripod may be needed.
 
PapaLazarou said:
This is what you need to do (Tripod mount the camera manual focus and use a small F stop) you cant go wrong.
Click to expand...

That's just a bit too simplistic. Even with a small aperture you still need to focus at or around the hyperfocal distance which as others have said is around 1/3 of the way into distance .
 
Sorry going to ask a question which you may think is a little silly :cuckoo:

I have a 7 point af camera (350D), whats the best way of focusing on something a third of the way in, without getrting it in the middle focus point.

Does that make sense?
 
Either turn off AF and focus manually...

or...

Using the Single Shot Focus Mode, (not Servo) select a single AF point. Focus on the point you wish to focus on. Press the Focus Lock Button with your right thumb. The focus point is now locked as long as you keep the button depressed and you can recompose your shot as you wish and take the shot.
 
I'll try and give you a rough example, in this image, the red arrow is (approx) the central focus point. By chosing this it's really too far away to get everything in focus (the near bushes will be OOF).
About a third of the way in is the yellow arrow, so I would use my selective focussing point until it was focussed on the area around the yellow arrow, which would give me a DOF that covers all the scene (at f22).
Not sure how the selective focus points work on a 350D (I only know it has this facility)

focus.jpg
 
That's a really great explanation. Thanks for that :thumbs:
 
Good man, Les
Thanks for spelling it out to us simpletons :thumbs:
 
I did mention this little free download on another thread, but with the Barnack software you can type in your focal length and aperture then the program will give you your Hyperfocal distance and DOF.

Here is the link http://www.stegmann.dk/mikkel/barnack/

Barnack is a program for learning about the intrinsic camera parameters and their effect on the hyperfocal distance, depth of field, field of view, et cetera.

The hyperfocal distance (hfd) is the focus distance that maximises the depth of field; range: [hfd/2;infinity]. E.g. if the hyperfocal distance is 5 m, then everything from 2.5 m to infinity will be in focus.

barnack_screenshot.png
Click to expand...
 
whiteflyer said:
I did mention this little free download on another thread, but with the Barnack software you can type in your focal length and aperture then the program will give you your Hyperfocal distance and DOF.
Click to expand...

Thanks for that, I don't understand it but I will study it hard :D
 
You must log in or register to reply here.
Back
Top