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Old Oct 4, 2010, 9:39 AM   #1
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Default Nikon D5000 focus help

I have a Nikon D5000 with the kit zoom and basic lens. I keep having a problem getting the focus "spot" on... especially when action is coming to me. I try manual and automatic. Here's a sample of what I'm talking about... Name:  princess.jpg
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Name:  race.jpg
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Name:  shatner.jpg
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All three pictures were from the same spot, same lens (70-200). I don't know if I'm fighting the movement, lens shake, narrow DOF or a combination of all of them.

An example of what happens under full daylight...
Name:  horse.jpg
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Is there a setting I should have that will "track" when using auto iris? Any other tips (aside from getting a new lens, which I would love but don't have the $$ for)?

Thanks
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Old Oct 4, 2010, 10:11 AM   #2
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Crap. I should have put this in the Nikon Dslr forum. Sorry.
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Old Oct 4, 2010, 10:13 AM   #3
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I moved it for you.
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Old Oct 4, 2010, 11:05 AM   #4
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The second photo, which appears about right to my eye, says that its focal length is 55mm. That's quite an accomplishment with a 70-200mm lens...
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Old Oct 4, 2010, 11:17 AM   #5
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A Nikkor 55-200mm f/4-5.6G IF-ED DX AF-S VR lens was used from what I can see of metadata interpretation using EXIF readers.

These are actually better than I would have expected using a lens that dim at that type of venue.

Part of the problem is slower shutter speeds (down to 1/250 second for the first and third images posted, even though they were taken at ISO 3200, which isn't fast enough to freeze all rapid movement).

I'd use AF-C (Continuous AF) to increase the percentage of keepers. But, a brighter lens (wider available apertures, represented by smaller f/stop numbers) would be desirable for those types of photos in those conditions, so that you could get faster shutter speeds to reduce blur from subject movement.
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Old Oct 4, 2010, 11:46 AM   #6
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Quote:
Any other tips (aside from getting a new lens, which I would love but don't have the $$ for)?
About the only other significant change you could make (other than using AF-C to help keep subjects in focus), is increase your ISO speeds even more (i.e., use ISO 6400 versus ISO 3200) if you're zooming much (since your lens gets dimmer as you zoom in).

But, increasing ISO speeds will increase noise (and loss of detail from noise reduction). So, it's a matter of balance/compromise (more blur using lower ISO speeds, less blur with more noise using higher ISO speeds), and there are trade offs either way.

If you zoom in much with that lens, you'll have a widest available aperture of f/5.6 (very dim for taking those types of photos in a stadium at night).

IOW, your lens is probably the primary limiting factor, and settings won't get around that part, as it can only let in so much light. A lens capable of maintaining f/2.8 throughout it's focal range would be a more desirable approach. f/2.8 is twice as bright as f/4 (the widest available aperture your lens has at it's wide angle zoom position) allowing shutter speeds twice as fast for a given lighting/ISO speed.

f/2.8 is 4 times as bright as f/5.6 (the widest available aperture you have with your lens when zoomed in towards it's longer end), allowing shutter speeds 4 times as fast for a given lighting and ISO speed.

If you can get close enough to keep from zooming in much (staying towards the 55mm end of the lens), that would give you an available aperture of f/4. But, if your subject is not occupying a large enough percentage of the frame (because you're not zooming in enough or not close enough), you won't get a lot of detail/pixels representing your primary subject.
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Old Oct 4, 2010, 12:20 PM   #7
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I'd love to get the $$ for a 2.8 lens, but wondering what that will do with my DOF? It should make it even smaller (narrower?), right? So wouldn't I still have problems?

Or is this more a problem of simply slow shutter speeds (which the 2.8 lens would help me increase)?
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Old Oct 4, 2010, 12:30 PM   #8
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I think you're probably seeing some of both. If you use AF-C (continuous Autofocus) and are careful of your focus point (and I'd probably set it to the Center AF point), that should help with any focus issues, since the camera's predicative AF algorithms will try to anticipate speed/direction of movement (although DOF will be narrower with a wider aperture, your desired focus point should be sharper).

A brighter lens will also help your camera's Autofocus Sensors to "see" better for faster and more accurate focus (even if you do decide to stop down the aperture some as needed for better DOF, since the camera will always focus with the aperture wide open, stopping it down to the aperture you set when it actually takes the photo).

But, 1/250 second is on the slow side for freezing any subject movement (as in the first photo in that set, where the waving hand is blurred from subject movement).

Also, if you underexpose your images and brighten them later because your shutter speeds are too fast for the lighting, aperture and ISO speed being used, you'll end up with more noise (and/or loss of detail from noise reduction), and will typically see "muddy" looking shadow detail, because the camera is just not getting enough light.

For shots "under the lights" at night, you really want to be using a lens with f/2.8 available throughout the zoom range. For example, a Nikkor 70-200mm f/2.8 AF-S VR lens (or on the budget end, a Sigma 70-200mm f/2.8 HSM lens), using ISO 3200.

I'm surprised the photos are turning out as well as they did using the lens you have on it.
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Old Oct 4, 2010, 12:41 PM   #9
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Thanks Jim.
Quote:
Originally Posted by JimC View Post
I'm surprised the photos are turning out as well as they did using the lens you have on it.
I'll take that as a compliment that I'm doing something right.
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Old Oct 4, 2010, 12:49 PM   #10
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IOW, I wouldn't complain about those results using the lens you have.

If you can't afford an f/2.8 zoom, try using AF-C and be careful of your focus point for a higher percentage of keepers. Carefully panning with any subject movement so that the subject is as stationary as possible within the frame (versus moving across the frame if you don't pan with the subject) can also help improve your percentage of keepers.
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