Decoding photo speak - help please!

[slr_newbie]

Ok, just a quick question today:

In reading a book about my camera, it says in reference to focusing on an object / selecting focal point:

"... reframe the image while retaining the focus (and exposure) that has been set."

How does one "reframe" the image? I assume that just means that if I lock in my focus that I can pan my camera to the left or right to include / exclude immediate surroundings while retaining the focus on the original focal point? I assume you must maintain the same distance to the original focal point?

This concept just confuses me a bit ... someone care to explain it to the newbie?

[engstrom]

You are correct, you can lock the focus by holding the shutter release button halfway down (unless you've changed the controls on the camera), then move the camera to reframe the shot. Be careful though, for critical focus you will actually be focused slightly behind the subject if you do this. The farther the subject is away from you the less you'll be able to tell about the slight focus shift.

[saber]

Engstrom and you are right. By halfway pressing the shutter release button you can reframe your image. But beware, if you use the reframing often the point you focussed on gets out of focus. More likely if you use a wide open aperture (smaller F-stop, like f2.8), due to the smaller depth of field.
I always use my multiple focus-points on my Rebelxt, that is beter than reframing while holding down the shutter release button.

I hope you understand this...

regards,

Frank

[Comanche]

Hi Anne - Frank and John are all correct. Like Frank, if I have time, I will go to the controls on my 30D (you didn't say what camera you use) and I can pick any one of the nine different points for the focus to work with. That assures a good, constant focus.

However - the problem with doing that is time. If you have time, use the single focus point you wish to use, but if you have to act quickly, you can always keep your camera set on using just the center focus point. Then, if you have one subject quite close to the camera, and another at a different distance away, you just focus on the subject you want in sharp focus, keep your finger on the shutter release button so it stays in focus, then recompose your shot to include both subjects.

Try it, just for the fun of it. Maybe your dog is nearby. Using just the center focus point, focus on the dog, then keep your finger on the "trigger". then move the camera so your shot now includes one of the dog's toys laying on the floor. Now press the shutter release the rest of the way down. The dog will be in focus, and the toy will be in the shot but out of focus.

That's what I did in this case. I focused on the teacher, then shifted slightly to include the kids in the background. I could have done what Frank suggested, but I didn't have time to fiddle with the camera.



Good luck - let us know how it works out.

[venchka]

Another area where autofocus lenses and cameras never meant for manual focusing can lead to perfect focus of the wrong part of the picture.