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Photography Question 
J M. Cunha
 

Focus seems off in Nikor lens 55-200mm vr


 
  Eleanora Cockatoo
Eleanora Cockatoo
Cockatoo, 55-200mm Nikor vr lens.
© J M. Cunha
Nikon D40x Digital...
 
  Rainbow with a Beak
Rainbow with a Beak
Sun Conure, 55-200mm Nikor vr lens.
© J M. Cunha
Nikon D40x Digital...
 
 
I have started doing some parrot photography lately. One problem I keep running into is that my Nikon D40x's 55-200mm lens seems to focus on one area. I can't get a general ("dynamic?" focus (where everything in an area is in focus). I also am having a hard time getting it to focus directly on the eye. For instance, if I put the "focus square" in the section containing the eye, it might still do the strongest focus on another section within that square--even if it's a close-up... I've included an image as an example.

Is there a better portrait lens for this? I do have an 18-55mm lens but it doesn't zoom enough...

Any help would be sooo much appreciated! Thanks!!!


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1/13/2008 8:20:03 PM

 
Gregory LaGrange
BetterPhoto Member Since: 11/11/2003
gregorylagrange.org
  I see some pixelation in the photos, so those aren't the best example to show.
But there is always one area of focus, more accurately called a plane of focus. You're wanting more depth of field, which technically is the area that appears in focus, but you always call it in focus.
If your aperture is wide you may not get the eye in focus if the bird tilts it's head slightly once you have your focus set. And it's amplified with longer focal lengths. For wider depth of field, smaller apertures.
If you need to use auto focus, your best results would be to compose the shot as you want it shot, and activate only the focus square that's in the area that the eye is. That is, if you were using the center of the viewfinder to focus, and then repositioning to frame for the shot.


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1/14/2008 2:56:53 AM

 
J M. Cunha   Thanks for your response. Re; pixelation--I'll try to go back and redo the images from the original cut. These were saved a few times in .jpeg as 'samples'.

Now, about the focus... could you explain a bit about the aperture?

"If you need to use auto focus, your best results would be to compose the shot as you want it shot, and activate only the focus square that's in the area that the eye is. That is, if you were using the center of the viewfinder to focus, and then repositioning to frame for the shot."

I need to use autofocus because the birds move so quickly. It's difficult to "compose the shot" and have time to MF. When I focus the square on an area that includes the eye, it often focuses harder on some other bit than the eye--the feathers in front of it or whatever.

Is there a lens that has a more general focus where everything in the pic would be "in focus" for example?

Thanks so much for your response--it's very helpful.


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1/14/2008 4:39:02 AM

 
Jon Close
BetterPhoto Member Since: 5/18/2000
  Wide open aperture, f/4-5.6 on your 55-200 lens, is going to give very shallow depth of field. To have greater depth of field (more of the bird in focus) you need to select smaller aperture of f/8 or f/11. The smaller aperture cuts the amount of light reaching the sensor, so to keep the shutter speed high enough to avoid blur from motion you'll need to use flash and/or set higher ISO to compensate.


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1/14/2008 7:52:13 AM

 
Gregory LaGrange
BetterPhoto Member Since: 11/11/2003
gregorylagrange.org
  Very wide angle lenses have just about everything in focus.
Aperture is like the pupil of your eye. Opens and closes down to regulate the amount of light. The effect it produces on the look of the photo is as the opening gets smaller, it makes the area behind and in front of the point of focus appear sharper and in focus.
The smaller the aperture, the greater the area. So it's deeper into the field of view that's in focus.
What also affects that is focal length, and how close you are to what you're shooting. So even with a very small aperture, if you are very close to something, like a few inches for a flower, the depth of field can be half an inch or even less.
If you use a long focal length, the depth of field can shorten to a small area even though you are far away.
Try your own experiment by finding something to take a picture of outside, anything stationary like a fire hydrant. Frame it at the short end of your zoom lens so that it fills the frame, top of the object at the top of the frame, bottom of the object at the bottom of the frame.
Then shoot it again at the long end, framing it the same way. All done at the same aperture. Then compare the two pictures.
You can practice focusing yourself to get better at it. Or you can do what many people do, use the continuous auto focus and just take a massive amount of pictures to increase the chances. Then delete the rest.


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1/14/2008 11:36:34 AM

 
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