| Author | Thread |
|
|
02/14/2005 12:55:50 PM · #1 |
Hi there Gang -- I have some concern about my 10d, and I'm trying to rule out user error. It doesn't always focus where it says it has. What I mean is that the "little red square" turns on, highlighting a point on the composition. When I view the composition on the computer, the part that's actually in focus was closer to the camera that the part that was indicated.
This is a HUGE drag when doing portraits: the nose is sharp, but the eyes aren't, even though the indicator was positioned on the eyes.
Generally speaking, this is a lot more noticeable when shooting close, using lenses open, as the DOF is short -- it's totally not an issue with stuff that's further away. Heaven forbid I should try using autofocus on a Macro shot using extension tubes.
Is there a way for "Joe Average" to test to see if the focusing mechanism is working correctly?
|
|
|
|
02/14/2005 01:08:05 PM · #2 |
That's a normal problem you get on a new camera until you manually select the Centre focus (can't remember how at the moment). Selecting Centre focus means that in any mode other than green square, the camera focuses on the centre of the screen, you can recompose the shot from there - instead of all the little dots focusing on all sorts of stuff.
BUT, in Auto mode (green square) it always picks what to focus on for you using all the red dots (the problem you're having now): you just have to pay special attention or just don't shoot in auto.
Message edited by author 2005-02-14 13:12:16. |
|
|
|
02/14/2005 01:33:56 PM · #3 |
What you have to keep in mind is that the actual focusing area is larger than the square. If the nose is a higher contrast area then it will focus on the nose over the eye if they both fall in the focus area.
Here is a focus test you can do. Focus Test There are numerous other tests online but they all rely on the same principals. Some front/back focusing is common.
Message edited by author 2005-02-14 13:37:30.
|
|
|
|
02/14/2005 01:36:45 PM · #4 |
I don't think that's what he's saying. All sorts of issues here. Which lens? The 10D has had backfocus problems with some lenses, most noticeably the 70-200 F4L. You may need to get your system calibrated by Canon. Also, its autofocus system isn't the best, in comparison to the 1-series or the 20D. If you're shooting at 17mm, for example, the focus doesn't often lock correctly. On my 17-40 I need to zoom to 40mm to focus lock and then zoom back out to compose. You can only do this on a parfocal (focus plane doesn't change when zooming) lens. My 50mm 1.4 also has issues finding good focus quickly, and often misses a bit.
Are you recomposing after focusing? At really wide apertures the focal plane of a lens like a 50 1.4 or an 85 1.8 will be very thin, and as it is not planar (the focal plane on lots of lenses is shaped in an arc) the focus will be off if you move the camera.
Try using autofocus and then manual focus. Also try different lenses. If there's a consistent focus error with a specific lens, it's likely that you're in need of a calibration.
|
|
Home -
Challenges -
Community -
League -
Photos -
Cameras -
Lenses -
Learn -
Help -
Terms of Use -
Privacy -
Top ^
DPChallenge, and website content and design, Copyright © 2001-2025 Challenging Technologies, LLC.
All digital photo copyrights belong to the photographers and may not be used without permission.
Current Server Time: 09/14/2025 11:08:23 AM EDT.
