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Controlled Focus

1414 Views 6 Replies 5 Participants Last post by  NE
How would I set up my camera so that it will focus on only a plant/fish/area and blur everything else (read: algae :mrgreen: ) around it? At the same time, how do I focus on my desired object? Usually, when I shoot, the camera just focuses (places some rectangle) on random things, instead of the object that I want for it to focus on.

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What kind of camera?

With the typical point and shoot camera you want to do two things. First and foremost is shoot in portrait mode. This is the part of the dial that has a framed shot of a person on it. That will get you the shallow depth of field you're looking for (Focused on target and anything in front of or behind is blurry).

The other thing you probably want to do is put your camera in macro mode which is used for close up focusing. This may look like a framed flower on some cameras.

It's a Canon PowerShot A80. I shoot in manual mode with flash turned off, macro mode turned on. I did the white balance thing. I fiddled around with various Exposure settings and ISO speeds. I just have trouble getting it to focus on a specific object. I try to place the area/object of desire in the center of the view finder, but the camera just does its own thing and focuses on some other area. Do you have any experience with this camera and can offer some advice? How would I get the narrow depth of field?

Oh, there's this (focus?) option where you are able to choose: Evaluative, Center Weighted Average, or Spot. Any thoughts on that?

Thank you very much.
to set the camera to just using the center focuspoint:

press menu button (in take picture mode)
set AiAF to off.
Return by pressing the menu button again.

Edit: Not available in Auto mode use P or some other mode (Tv,Av or M).


From what I see here this camera has both Focus Lock and Manual Focus. Both will help you to focus exactly on what you want, even if it is offcenter.

Focus Lock is a setting that you have to set using the Menu of the camera. Usually pressing the shutter release button half way down locks the focus on whatever object the camera has focused at the moment. If you hold the button half way down and point the camera somewhere else it does not try to refocus.

The Autofocus on any camera can encounter situations in which it will have trouble. Reflections, dark objects, or fine mesh would be the simplest examples - the camera cannot decide what exactly to focus on. I have noticed that the aquarium glass, especially if shooting under an angle, also poses a problem for Autofocus sometimes.

In my opinion using Manual Focus in macro mode is the best choice (if you can see well or are not too tired).

cS said:
How would I set up my camera so that it will focus on only a plant/fish/area and blur everything else (read: algae :mrgreen: ) around it?
As simple as setting your Aperture up and down.


f/2.8 - short depth of field (* face of fish in focus while rest of the body blurred)

f/11 - long depth of field (* face and body in focus)

Applied your aperture settings to your plant photography and you should get desired effect.

There is also good old PhotoShop. If you need tips, let me know.
I shoot, the camera just focuses (places some rectangle) on random things
This camera has Artificial focus inteligence and if you dont turn that off the camera chooses which focus point (1 or more of 9) it will use by it self,
you can shut off this behaivour as in my previous post but i forgot to write that you must use another mode than AUTO (in AUTO the camera always use the AiAF).
Or use manual focus (also not available in AUTO) by pressing the flower twice.
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