Auto Focus

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Berto

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Can someone help.

i have found when i am taking photos of moving cars that the focus just dosen't seem sharp enough. i have the shutter speed up high (so its not that) i have auto focus selected on the lens but is there diffferent modes of auto focus on the camera?

sorry for my lack of knowledge on this.
 
What camera?
They are not all the same. You may have the choice of single focus and continuous focus. Use continuous focus for moving subjects.
 
sorry forgot to add the camera.

Canon 1D MK11 N

As in AI Servo setting for continuous?
 
Berto said:
sorry forgot to add the camera.

Canon 1D MK11 N

As in AI Servo setting for continuous?
Click to expand...

Yes, if you have it set to AI Servo and use the centre focus point, the camera will continually re-focus on the object the focus point has fixed on to.

If you've not chose the centre focus point on your previous shots, that may be one of the reasons your out of focus :thumbs:
 
me back again.

i have now set the centre focus point on my camera. i have been thinking though sometimes the focus is out on the first shot.

i had a look through the custom functions and fond the following info

C.FN 19
Lens AF stop button function
0:AF stop
1:AF start
2:AE lock while metering
3:AF point:M Auto/Auto Ctr
4:AF mode: ONE SHOT AI SERVO
5:IS start

what should i select? or would this even make a difference?

again not sure what i should have selected here on this custom function.

C.FN 21
Drive speed priority AI SERVO
0: Disable
1:Enable

another custom function that may make a difference. i take it select one of the center points?

C.Fn 13
Number AF points/Spot metering
0:45/Center AF point
1:11/Active AF point
2:11/Center AF point
3: 9/Active AF point
4: 9/Center AF point

C.Fn 17
AF point activation area
0:Single AF point
1:Expand (TTL of 7 AF points)
2:Automatic expand (max. 13)

C.FN 04
Shutter button/AE lock button
0:AF/AE lock
1:AE lock/AF
2:AF/AF lock, no AE lock
3: AE/AF, no AE lock

sorry for the lack of knowledge on this, but if you can help that would be great as it is becoming a pain.
 
Try these

C.FN 19
Lens AF stop button function
0:AF stop

C.FN 21
Drive speed priority AI SERVO
0: Disable

C.Fn 13
Number AF points/Spot metering
1:11/Active AF point

C.Fn 17
AF point activation area
0:Single AF point

C.FN 04
Shutter button/AE lock button
0:AF/AE lock
 
thanks snapzz.

i had one or two of them selected different. so hopefully thats it sorted.

thanks again.
 
Berto said:
C.FN 19
Lens AF stop button function
0:AF stop
1:AF start
2:AE lock while metering
3:AF point:M Auto/Auto Ctr
4:AF mode: ONE SHOT AI SERVO
5:IS start
Click to expand...
This is only relevant if you're using a big white telephoto (eg 300mm f/2.8) which has control buttons on the lens. You can see the button down toward the front of the lens here. CFn 19 determines what that button actually does - start or stop the AF, start the IS, etc. Which setting you use depends on your style. But it won't affect the sharpness of your photos.

ef_300mm_f2.8_l_is_usm_v2.jpg


Berto said:
C.FN 04
Shutter button/AE lock button
0:AF/AE lock
1:AE lock/AF
2:AF/AF lock, no AE lock
3: AE/AF, no AE lock
Click to expand...
This determines what happens when you half-press the shutter button. The default setting (0) is for focus-recompose use; the camera both focuses and meters, but only the focus is locked in for as long as you half-press the button, and if you want to lock in the exposure then you do that with the * button. The other settings move these around; for example with C.Fn04-3 you use the * button to focus. Which setting you use depends on your style; for motorsport the default should be OK.
 
looking at one of the photography guides on this forum i found this below.

"f/2.8 = shallow depth of field – only one thing in focus, everything behind and in front is blurred
f/22 = deep depth of field – most things in focus"

which should i use to take photos of motorsport?
 
What lens are you using?
 
Back to basics:
Switch everything to manual, select a focus point on the road and trip the shutter immediately before the front of the car hits that spot...with practice you'll get sharp images.
After you master the manual approach, switch to single-point AF and do the same thing - anticipate the car's movements and trip the shutter accordingly.
Once you've mastered that technique, switch to multi-point/dynamic focus (or whatever it's called on your camera) and do it all over again.

Apart from the D3x that I just got last week, I've never had an AF camera do exactly what the manufacturers claim in terms of predictive follow-focus in AF mode...

Be glad you're shooting digital - I had to learn all this on film...it got expensive back then!
 
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