Please help - need advice about FOCUS

[CLN]

I've been feeling frustrated with focus issues. All of my shots seem soft. So I did a little test.

I focused on the number 16 using my center focus point and BBF. Looks to me like it actually fell on the #1 of 15.




ISO 800
1/1000 sec
f/1.4

RAW file, unsharpened

I tried this with a variety of apertures (from 1.4 up to 5), and also with a couple of my outer focal points.

In all cases the focus fell somewhere between the 13 and 15 - definitely not on the 16.

Was holding very steady (but at 1/1000 should be fine right?).

Is this what they mean when they say your focus falls "behind"? How do I compensate for this? Or is there something wrong with my camera/lens?

I'm shooting with a D90 and a 50mm 1.4 lens.

Genuinely appreciate any suggestions or comments. I guess I should swap out the lens and see if I still have this problem. I'll do that, but the baby is awake now so might be awhile. Thanks again.

[Henry Wilt]

Have you cropped the picture? because It does look like the edge of the ruler at the 15 mark appears to be dead centre. If not, try "this focus test" to make sure everything is accurate before you worry about getting your lens checked.

[RecurrentNerve]

Try going into your menu and turning on the manual focus rangefinder. This tells you if your point of focus is in front of or behind the subject. So, turn it on, use autofocus as normal, then flick to MF and check the rangefinder (it uses the exposure meter in your viewfinder). A tripod will probably be useful.

[sk66]

Assuming you didn't make any focusing mistakes, this is what is called "back focus", and a pretty bad case of it as well.

Three things to do to isolate "the problem":
Instead of using autofocus and center point, select the focus point you wish to use to avoid reframing/refocusing errors.

Try manual focus to determine if it is a lens issue.

Try tripod liveView mode to determine if the focus sensor is out of alignment.

[Aegea]

Also, have you tried this test with other lenses? That might identify whether it's a lens or camera issue.

Leon Goodman's site My Photography discusses focus issues in depth in the context of a D70, but is still applicable to D90's.

[MrJones]

you can't really test this issue while holding the camera in hand.
you need to use a tripod to keep it in place and steady cause each movement of your body backward or forward, even the slightest) will throw you off focus.

do a controlled test and come back with the results.

[dakwegmo]

Originally Posted by CLN

Was holding very steady (but at 1/1000 should be fine right?).

It would only be fine if you can be sure you're not moving at all from the time the camera locks focus through pressing the shutter until the camera actually records the image. It's definitely possible you moved 1 cm or more during that process, so you need to do this test with the camera on a tripod. Or at the very least, sitting on a stable surface like a table or counter top.

[sk66]

Originally Posted by dakwegmo

It would only be fine if you can be sure you're not moving at all from the time the camera locks focus through pressing the shutter until the camera actually records the image. It's definitely possible you moved 1 cm or more during that process, so you need to do this test with the camera on a tripod. Or at the very least, sitting on a stable surface like a table or counter top.

Don't know how I missed that...If hand held, the "problem" is almost certainly the user...

[Aegea]

Well, the OP did say he repeated the test with different apertures, etc., so it may perhaps not be user error. But, definitely, a tripod should be used.