need help please, question about DOF

[gail]

Hi all I'm wondering what setting do I use to get all the picture in focus? Like if I want no DOF. Like when I focus on something the background will be blurred a bit. I want all in focus. I'm confused really hope you all understand what I'm trying to say ha. :roll:

And how do I get a more of DOF? more blur? Some times I want to blur the back ground out completely but I can't get it to work for me. What I'm trying to say is when I focus on something that will be in focus and the rest of the pictures will have a blur to it.
Camera I am using is DRebel. with 75-300 lens and EF 50mm f/1.8II

For example this pic of the kittens.

4... kittens and the 1 kitten to the right the little black one is blurred so if I want all 4 kittens in focus what setting would I use?
Could it have been the lens I was using?

http://photos.imageevent.com/gailsgallery/miscthisandthat/websize/kittens.JPG

And here for example the horse.
I want more of the background blurred but I played around with it and never could get more blur to it. So what am I doing wrong? :oops:
:oops: I feel embarrassed to have to ask this but I know some of you can help me out. Please go easy on me. I'm still learning. :oops:

I was using the Canon 75-300 lens for theses shots and setting was in P mode. And I also tried Av. and moved the aperture up and down from like 5.0 up to 22 ...I wanted more DOF in the background on the house pic. I wanting to have more of a blur behind the horse. Can someone help me here? I would greatly appreciate it very much. Thanks
http://photos.imageevent.com/gailsgallery/miscthisandthat/websize/horse.JPG

I'm going out tomorrow to take some more shots of my granddaughter and I wanted to learn how to do that. Cause I want to be able to just get focus on her and have all in behind her blurred out. Thanks :)

http://photos.imageevent.com/gailsgallery/samantha/large/12.JPG

And in the pic of my granddaughter. I would have liked to had more blurred, DOF" behind her also.
Thanks I'm sorry to be so much TROUBLE...I will do better next time I promise. :P :roll:

[Olegis]

I would suggest to read this article (http://luminous-landscape.com/tutorials/understanding-series/dof.shtml) from Luminous-Landscape.com, it has great explanations on this topic.

[Vinny454]

Basically if want all the kittens in focus, you need a smaller aperature (larger F stop number). If you want the backround of the horse more blurred, then you want a larger aperture (lower F stop number)

Here is link to a site you should bookmark. Great info.

http://www.luminous-landscape.com/tutorials/understanding-series/dof.shtml

Vince

[Vinny454]

I would suggest to read this article (http://luminous-landscape.com/tutorials/understanding-series/dof.shtml) from Luminous-Landscape.com, it has great explanations on this topic.

You beat me to the punch as I was typing out the message. It's the same link Gail.

Vince

[gail]

Thanks olegis, for the article. Maybe this will help me to understand it a bit more.

[Olegis]

3 minutes, Vince 8)

[Aylwin]

Generally speaking, the lower the aperture number, the more blurry the background gets. So if you want to increase the blur, reduce the aperture number. Av mode is probably the best for this.

So for your grand daughter's photos (and even the horse if you can get close enough), I suggest you use your 50mm and start from f/1.8. You'll get very limited DoF so remember to focus on the eyes.

For the kittens, then it's the reverse: increase the aperture number.

[Jesper]

Cute little kitties !!!!! :D

Here is an online depth-of-field calculator:
http://dfleming.ameranet.com/dofjs.html

You enter your camera type, focal length you're shooting at, the aperture and the subject distance (the distance to the subject you're focussing on) and it will tell you the near and far limit of the range that will be "acceptably sharp".

For the kittens, you want a larger depth-of-field, so you should use a smaller aperture (larger f-stop number). You can put the camera in Av mode and choose the aperture, and let the camera choose the appropriate shutter speed to get a good exposure. Note that if you "stop down" (use a smaller aperture), the shutter speed will be slower. If it becomes too slow, you'll get motion blur. To avoid this, choose a higher ISO setting or use flash.

For the portrait, you want a smaller depth-of-field, so you should choose a larger aperture (smaller f-stop number). If you want to get more background blur, you can also try making the distance between the subject and the background larger (if the subject is close to the background, the background will inevitably be more in focus than when it's further away).

If you have your camera in Av mode, you can use the depth-of-field preview button (at the bottom of the lens mount, at least on the 10D) to get a preview of how the DOF is going to be. Note that if you press and hold the button, the viewfinder will get darker (if you've stopped down). Normally if you look through the viewfinder, you are looking with the lens at max. aperture. The DOF preview button stops down the lens (what normally happens at the moment you press the shutter release button), so that you can preview what the DOF is going to look like in the photo.

[Littlenose]

If you have your camera in Av mode, you can use the depth-of-field preview button (at the bottom of the lens mount, at least on the 10D) to get a preview of how the DOF is going to be. Note that if you press and hold the button, the viewfinder will get darker (if you've stopped down). Normally if you look through the viewfinder, you are looking with the lens at max. aperture. The DOF preview button stops down the lens (what normally happens at the moment you press the shutter release button), so that you can preview what the DOF is going to look like in the photo.

Thanks for this Jesper... until I read this i didn't fully understand the DOF button :D