auto focus

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tea2085

Senior Member
Is there a way to check the accuracy of your camera's auto focus? I have a 3300 and I swear the pictures my 10 yo son takes withe his new 119 dollar pentax have more clarity than my camera. I have the kit lens and a Tokina 12-28
f4 wide angle lens. A lot of my pics have poor focus. I use back focus now exclusively but the traditional "push the button halfway down" method produced poor focus as well. Paul
 
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480sparky

Senior Member
First, check to see which focus point is being used by the camera. Nikon has free software on their site that will show you this.
 
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Don Kuykendall_RIP

RIP :(
tea2085 said:
Is there a way to check the accuracy of your camera's auto focus? I have a 3300 and I swear the pictures my 10 yo son takes withe his new 119 dollar pentax have more clarity than my camera. I have the kit lens and a Tokina 12-28
f4 wide angle lens. A lot of my pics have poor focus. I use back focus now exclusively but the traditional "push the button halfway down" method produced poor focus as well. Paul
Click to expand...


What focus mode are you using? There are a lot of different modes and some are just for very specific scenes. Make sure you are using the correct one for for how you are shooting. Also when you are using BBF it should be set of AF-C. So when you are focusing on a stationary object you will focus and then release and the recompose and shoot. I personally use the single spot focus and then I can pick the object that I want to make sure it is focus the best.

I had a problem with my wife's shots being out of focus 2/3s of the time with her D7000. She does not use BBF so it is the half press method. Every time I would check to see what the problem was with focus it would be perfect. I finally figured out that when she would take a photo whe would just look through the viewfinder and push the button all the way down without giving the camera time to focus.

One other thing you might want to check is your shutter speed. The best way to use the reciprocal rule is that the shutter speed of your camera should be at least the reciprocal of the effective focal length of the lens. You will need to modify that a little since you use a DX camera. With the DX camera you need to change that to 1.5 or even twice the shutter speed. say you are using a 50mm lens then you would need to use at least 1/75th sec or as close to that as possible. Bot sure about the D3300 but many of the DSLRs have Minimum Shutter speeds that can be set under the AUTO ISO settings, Some have only the speed but a few of the newer ones have a AUTO setting under minimum shutter speed. If yours has that I would suggest that you use it.
 
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tea2085

Senior Member
Thanks Don and Sparky, I will use this info in future shoots. I have to digest what Don said about shutter speed!! Paul
 
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aroy

Senior Member
tea2085 said:
Is there a way to check the accuracy of your camera's auto focus? I have a 3300 and I swear the pictures my 10 yo son takes withe his new 119 dollar pentax have more clarity than my camera. I have the kit lens and a Tokina 12-28
f4 wide angle lens. A lot of my pics have poor focus. I use back focus now exclusively but the traditional "push the button halfway down" method produced poor focus as well. Paul
Click to expand...

Here is how you can check the AF accuracy. Use these camera settings

. ISO 100 (not Auto)
. Mode "A"
. Aperture Wide open, For kit lens use 55mm at F5.6
. AF Area Mode - Single point
. Focus Mode - AFS
. Metering - Matrix
. Select Centre AF point
. If you have a garden or a back yard, mount the camera on a tripod and point it to a fence or a chair or a table. If you do not have a tripod, set the camera on a stable surface - flat table or a chair
. If using a fence set the camera at an oblique angle and focus using half press at an edge.
. Once satisfied with the focus press the button fully.
. If you want to negate camera shake, use burst mode to shoot 6 or 8 frames in a burst.

Now check the images in your computer. If the camera if functioning properly then the edge you aimed at should be in focus. If the sharp focus is away from the edge you aimed at, then the AF is off.

One way to get sharper pictures is to use faster speed - 1/250 or more and smaller aperture F8 or more, but that requires more light, (flash if there is insufficient light) or high ISO.
 
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