focus troubles nikon d5100

[chloewindle1]

I've posted before about having focusing problems with my nikon d5100. I photograph horses as most of you know and have had trouble snapping the horse in action over jumps as it's been focusing on the jump or the background so the moving object is blurry. I shoot manual mode and know exactly how to use it. I've tried shooting dynamic, 3D tracking, single point and manually focusing it but nothing seems to work. I normally hold the button half way down to focus it on the horse and last min press it when the horse is jumping which worked with my nikon d3100 ect so surely the d5100 should be more advanced with things? I'm getting rather annoyed as getting booked up with photoshoots and event photography so this need's to get sorted. I generally have no clue on what's going on and what i may be doing wrong?

 

[Derrel]

Are you using AF-S focusing mode, so that the press-focus-and-HOLD of the shutter button actually holds the focus point? A photo or two with EXIF info still intact might help troubleshoot this issue.

 

[chloewindle1]

no I've been using continuous-servo AF, is that where i'm going wrong???

 

[Derrel]

It's difficult to say from 7,000 miles away, Chloe. Autofocus can be a tricky business, with multiple settings options...so,so,so many options that can potentially trip one up. Continuous AF will try to re-focus quite often, and it WILL SHOOT out of focus subjects. With the camera set to AF-Continuous, it CAN take out of focus images, at times. In AF-S the camera requires a Focus Lock Confirmation before it will fire, which can be a good thing--OR it can be a bad thing, by causing a person to MISS the opportunity to take a shot that the camera says is a tiny bit out of focus.

Another issue could be the lens; if it's a slower lens like say a 70-300 f/4.5~5.6, focus might not always be dead-on. Annnnnnnd, in AF-Continuous, the camera WILL allow a slightly OOF image to be taken. How fast, accurate, and repeatable and predictable a camera focuses is many times, dependent on the exact LENS used on it. In general, I've found that my 70-200 and 80-200 f/2.8 lenses focus better (a slight bit faster than my 70-300 f/4.5~5.6, but much more-RELIABLY). Missed focus on action work like horse jumping is the kind of issue I would want to see 50 images from, and carefully examine their EXIF data, and also ask yuo questions about the situations and the settings and the way you used the camera itself, before trying to really diagnose the issue.

We really do not have enough information or background here to say definitively what the issue is, or how to alleviate/avoid the issue.

 

[astroNikon]

On my newer camera I was having focusing issues for sport until I turned off all of the "helper" features - Auto Distortion, Long Exposure NR, High ISO NR, things like that. Then my camera started working the way I knew it could. It was really strange .. the release was slightly delayed and the entire cycle of mirror up / down for contnuous sounded really weird, timing of the shots, and focusing issues. I turned off everything and it sounds normal and now shoots fine, and when I miss a shot it's now mostly me (or a fence background type issue).

 

[SCraig]

You know exactly where the horse will be, it will be right over the jump. Manually focus on the jump, use enough aperture to give you depth of field that will cover the the jump from near to far, then just pan with the horse until it jumps. People photographed them that way for decades before autofocus was invented. Learn from their methods.

 

[KmH]

no I've been using continuous-servo AF, is that where i'm going wrong???

AF-S is a focus-priority mode and the camea shutter will not release if focus has not been achieved.

AF-C is a shutter-priority mode and the shutter will release if focus has not been achieved.
When using AF-C some % of the images you rake will be out of focus (OOF).
The better photographers get at using AF-C the lower the % of OOF photos they will get, but they will nonetheless get some that are OOF.
What the photographers get better at is anticipating the action and knowing which AF point to use.

worked with my nikon d3100 ect so surely the d5100 should be more advanced with things?

No, not surely at all.

The D3100 and the D5100 both use the same Nikon Multi-CAM 1000, 11 AF points, 1 cross-type (the center point) Auto Focus module. (D3100 specifications, page 197 of the reference manual, D5100 specifications, page 229 of the reference manual)
The Nikon Multi-CAM 1000 AF module does not do 3-D tracking very well.
Since the Multi-Cam 1000 AF module only has the 2 center cross-type focus point, that is the one to rely on the most when using AF-C.

You might also want to consider using 'back button focus' by moving the AF function from the shutter release to the AE-L/AF-L button on the back of the camera.
The AE-L/AF-L button on the back of the camera can be set to AF-On - See the Custom Settings menu f2 on page 166 of your D5100 reference manual.