Is my lens back focusing?

hewhoknows

hewhoknows

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Matt
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Ive been shooting alot of ice hockey just lately and loosing 80% of my images due to the players being out of focus. Last weekend I purposly shot some very slow moving subjects (not stationary as i get no problems then) just too see if I could identify if its user or equipment error.

I found this shot I took of 2 players, one behind the other, and viewed it through Nikon ViewNX so I could highlight my focus point. This image has had no processing and is straight out of camera. As you can see i firmly focused on the player in front who is shown OOF, however the player directly behind is showing pretty damn sharp. Settings were:

Nikon D90
Sigma 70-200mm f2.8 lens
f2.8
1/320th
ISO1600
AF-C focusing
Matrtix metering

Now ive done loads of research on how best to shoot low light fast indoor sports so feel i know what should be working for me from a settings point of view. Plus I have produced several really nice images but on alot of occasions im not getting good fopcus on the subjects within my focus point and instead the background players or boards are more in focus them the subject.

Anyone have any ideas, do I have a lens that needs servicing or do I just need to try harder with my technique?


Backfocusing issue? by Matt_Giles, on Flickr
 
I'm not surprised. It sounds like you're expecting a D90 and Sigma zoom to servo focus and nail it every time with a moving subject in difficult light.

You won't score 100% hit rate with that even using a D3 and top grade Nikon lens. No disrespect to Sigma, but they have to reverse engineer their lenses, and they have to come up with a compromise to suit all brands and models.

You might want to check with Sigma that you've got the latest firmware chip, but the fact that it's okay with a stationary subject suggests that the problem is the focus tracking which needs both the camera and lens to be spot on.
 
In my experience the mk2 Sigma is as good as the mk1 Canon f/2.8 version when it comes to AF in low light sports so I would expect the Nikon mount to be as good. Can't comment on the d90's AF but you should be getting more than a 20% hit rate with that combo.

Definitely worth checking the firmware is up to date and if it is back focusing Sigma will check and sort it (even 'tuning' it to your own body) free if it's in warranty.
 
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If I shoot action shots at f2.8 I struggle to get any good shots to be honest, maybe that is just me but do you need to shoot at f2.8?

I used to try and shoot at f2.8 and used to get poor shots, I then started shooting at f8 and now pretty much every shot it spot on.
 
For indoor sport f/2.8 is a must, even with a very good high iso body.

It's just setting it up and getting used to the limits that you need to master.

You're right about stopping down when you can though, but not as far as f/8 for sports as you are limiting your shutter speeds unless panning.
 
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I have not done much indoor sport.

Have shot plenty of Speedway outside under poor light at f8 at 1/250s with good results.
 
ashaz said:
lol. Lobby-slow moving!!!! How is he getting on down there?
Click to expand...

Im not from Guildford mate so not so sure how he is getting on. He is a fantastic player though, I played GB u21;s with him years back and he was awesome then. One of my best mates plays for Guildford so ill get the low down on how he's progressing ;)
 
hewhoknows said:
Im not from Guildford mate so not so sure how he is getting on. He is a fantastic player though, I played GB u21;s with him years back and he was awesome then. One of my best mates plays for Guildford so ill get the low down on how he's progressing ;)
Click to expand...

Thanks, we miss him up here on Tyneside.
 
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