Autofocus problem....
Discussion
I took alot of pictures today up at knockhill. I dont tend to look at the pictures as I take them, the first few perhaps to make sure I've got my settings right. Anyway, I put them all on the computer and I've got several that look like this
It just so happens that I noticed this pic when I took it, I also got a few more after it.
The camera is a 400D, the Lens is a Sigma DG 70-300. I manually selected the autofocus point as the centre point.
Its not unusual for me to get the odd out of focus shot, especially when panning. I thought I was having one of those days, but that pic isnt focused at all. I've got a couple from last year where the grass in front is focused or that barrier behind is. I'm also not sure why the camera let me take the shot, usually if it hasnt locked the focus it wont shoot.
Is this a problem with Sigma lenses or is there someway I can speed up the autofocus with settings on the camera. Or am I just being a numpty.
And just to prove that I can use the camera...
It just so happens that I noticed this pic when I took it, I also got a few more after it.
The camera is a 400D, the Lens is a Sigma DG 70-300. I manually selected the autofocus point as the centre point.
Its not unusual for me to get the odd out of focus shot, especially when panning. I thought I was having one of those days, but that pic isnt focused at all. I've got a couple from last year where the grass in front is focused or that barrier behind is. I'm also not sure why the camera let me take the shot, usually if it hasnt locked the focus it wont shoot.
Is this a problem with Sigma lenses or is there someway I can speed up the autofocus with settings on the camera. Or am I just being a numpty.
And just to prove that I can use the camera...
Sigma are no where near as fast as OEM lenses, if they're not somewhere near the focus point they can wander off & aimlessly hunt between both extremes (close/infinity).
I use a Sigma 70-200 f2.8 for indoor shots of Ice Hockey during winter Months & I'm on the light/focus limit even @ 1600asa.
I found for best results to pre-focus on an area close to where the subject will be - this gives the autofocus a better chance.
I use a Sigma 70-200 f2.8 for indoor shots of Ice Hockey during winter Months & I'm on the light/focus limit even @ 1600asa.
I found for best results to pre-focus on an area close to where the subject will be - this gives the autofocus a better chance.
AF is set to AI Servo.
The thing that is bugging me is I had 2 trips to Le Mans last year, 24hr and Classic and the BSB's at Knockhill and never had any problems like this.
I did notice that the lens was doing an awful lot of that aimless searching, as well as getting stuck at one of the extremes, and then shuddering when trying to get the focus back again.
The thing that is bugging me is I had 2 trips to Le Mans last year, 24hr and Classic and the BSB's at Knockhill and never had any problems like this.
I did notice that the lens was doing an awful lot of that aimless searching, as well as getting stuck at one of the extremes, and then shuddering when trying to get the focus back again.
In bright conditions the Sigma's are fine but I noticed the shots you have posted may have been taken on an overcast day?, this won't help.
Also, if a series of shots are out-of-focus, this is because the lense is hunting back to the same focus point all the time..........to be safe, you really need to get it pre-focused somewhere near your subject first......does this make any sense to you?
Also, if a series of shots are out-of-focus, this is because the lense is hunting back to the same focus point all the time..........to be safe, you really need to get it pre-focused somewhere near your subject first......does this make any sense to you?
Similar position myself last week at WSB Donny. Sigma 70-300A PO.
I dont think the Siggy is capable of focusing at the speeds required for bikes.
Works ok ish on cars but in photography terms, is a very cheap lens and has limitations in my view.
Would change mine in a shot, but finances dictate I have t hold on to it for while yet.
I dont think the Siggy is capable of focusing at the speeds required for bikes.
Works ok ish on cars but in photography terms, is a very cheap lens and has limitations in my view.
Would change mine in a shot, but finances dictate I have t hold on to it for while yet.
tvradict said:
Thanks for all the replies. I had a feeling the top answer would be 'buy a better lens you f
g cheapskate' 
It wasn't so overcast today. The AF seemed to get on much better. still had the odd crap shot though.
You're always going to get a bunch of crap images, everyone does, no matter what!g cheapskate' It wasn't so overcast today. The AF seemed to get on much better. still had the odd crap shot though.
I used to go through 30+ rolls of velvia over a typical MotoGP/WSB/BSB weekend, that's over 1,000 images without getting to see any results until processing the next day.
The more you take, the more success you will have
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