3D tracking cervo or single point cervo?

[tanjonhan]

hi guys, i went for the wakeboarding championships at marina bay over the weekend...first time shooting a faster sporting event, and faced some problems which i would like to seek help and advice on..

Taking the wakeboarders do their stuff in the water, i found that it was difficult to use the 3d tracking to focus on them. I started tracking them as they approached the waves, and as soon as they started their stunts i pressed the shutter, only to see the tracking focusing point lock on for a short while and then suddenly jumping erratically to the bright reflections on the sea water below the wakeboarder.

So my conclusion is, not that effective...

THen i tried single point cervo, seemed to work better in a way, only that on my part, i was incompetent in maintaining focus on the wakeboarder half way thru the stunt, especially when they start to do some twist and turns....what i m curious about is whether the camera was not able to adjust focus fast enough or was it that it was in the midst of adjusting and just missed all the rest of the shots?

My setup was a D300, battery grip with AA batteries, 8fps, 70-200 VR.

Apart from that, does f/2.8 focus faster than f/4 on the same lens?i think it should?but just checking...

Lastly, can anyone share their experiences and tips on fast action photography?(my first question, what i experienced is normal right...?that its impossible to get majority of your shots in pin sharp focus......)..


haha thanks

[chisiang]

from my experience, 3D tracking is useful when the background is relatively clean, ie tracking birds in flight. When you start to pan and track, the 3D will track the background movement instead if the panning is slow.

For approaching subject, 3D is phenomenon. For slow side-way panning, it's a hit or miss. One way to go about it is to re-acquire your subject every now and then. Another tips is to use the AF button instead of pressing the shutter half way.

[lsisaxon]

Originally Posted by tanjonhan Apart from that, does f/2.8 focus faster than f/4 on the same lens?i think it should?but just checking...

Same lens but different aperture settings? Other than LV mode, metering and AF is always performed at the maximum aperture regardless of the set aperture and it is only stopped down prior to the shot being taken, so the answer is no, there should be no difference in the AF speed.

[tanjonhan]

Originally Posted by lsisaxon Same lens but different aperture settings? Other than LV mode, metering and AF is always performed at the maximum aperture regardless of the set aperture and it is only stopped down prior to the shot being taken, so the answer is no, there should be no difference in the AF speed.

thanks for confirming =)

[tanjonhan]

Originally Posted by chisiang from my experience, 3D tracking is useful when the background is relatively clean, ie tracking birds in flight. When you start to pan and track, the 3D will track the background movement instead if the panning is slow. For approaching subject, 3D is phenomenon. For slow side-way panning, it's a hit or miss. One way to go about it is to re-acquire your subject every now and then. Another tips is to use the AF button instead of pressing the shutter half way.

hmm, how does the mechanism for using the AF button make it a better choice compared to the shutter..?

Makes sense on the camera tracking background if panning is slow, maybe mine was not fast enough..especially when the wakeboarders engaged their stunts..in this case, do you have an suggestions on better alternatives..? I was thinking, if my zoom power is stronger, such that the subject takes up more than just one focusing rectangle, it would be easier to focus compared to a subject that only fills up one focusing rectangle rite..?is that how the super tele lenses get a higher hit rate for sharp focusing..?

[chisiang]

Originally Posted by tanjonhan hmm, how does the mechanism for using the AF button make it a better choice compared to the shutter..? Makes sense on the camera tracking background if panning is slow, maybe mine was not fast enough..especially when the wakeboarders engaged their stunts..in this case, do you have an suggestions on better alternatives..? I was thinking, if my zoom power is stronger, such that the subject takes up more than just one focusing rectangle, it would be easier to focus compared to a subject that only fills up one focusing rectangle rite..?is that how the super tele lenses get a higher hit rate for sharp focusing..?

I used to hold the shutter half down and some of the time I triggered the shutter. And you become paranoid with it as such some times you don't dare to press too hard causing NO focusing at all or you became retard it's more like slow finger reflex reaction rather than mechanically/electronically superior. My bad for leading you to think that way.

With the AF button pressed using your thumb, your index is always on the standby to trigger. I find it more efficient but will need some getting used to. Also, I find the finger reflex is faster if you want to re-acquire focus, by fast tapping.

On longer lenses, AF lock buttons are built into the end of the lens as well.

Quote: I was thinking, if my zoom power is stronger, such that the subject takes up more than just one focusing rectangle, it would be easier to focus compared to a subject that only fills up one focusing rectangle rite..?

Yes.

[Jeff]

u r probably focal length limited (overall), such that u dun get to enjoy the max performance offered by the AF system.

simply, u are asking the processor in ur cam to perform too many complex calculations to isolate the subject from the environment. Probably >90% will be miss, maybe 1% will yield if u r lucky, if u use 3D tracking.

if u play around with different AF settings, and AF point, u will learn that the best would be to disable the AF lock, select a single AF point in portrait and use the second top-most sensor (11-sensor active) to track ur subject in the waves. No i couldn't agree with reports that 3D tracking can be be used for everything. reassign the AF function to the AF-On. Seasoned sports photog will tell u its almost a god sent to be able to tell the cam when to stop focusing by this method. Rather than letting the cam decide when to start or stop AF tracking, u can control by releasing and depressing the AF-On as and when u wish. humans r still smarter

ur hit rate should increase dramatically, with proper panning technique in place, to 80%.

it takes a while to really understand and appreciate the AF functions. it can be really frustrating or a god sent depending on how u use it.

n usually for sports, one would prefer at least a monopod to plan. no fun with kilos on urs arms.

[tanjonhan]

Originally Posted by Jeff u r probably focal length limited (overall), such that u dun get to enjoy the max performance offered by the AF system. simply, u are asking the processor in ur cam to perform too many complex calculations to isolate the subject from the environment. Probably >90% will be miss, maybe 1% will yield if u r lucky, if u use 3D tracking. if u play around with different AF settings, and AF point, u will learn that the best would be to disable the AF lock, select a single AF point in portrait and use the second top-most sensor (11-sensor active) to track ur subject in the waves. No i couldn't agree with reports that 3D tracking can be be used for everything. reassign the AF function to the AF-On. Seasoned sports photog will tell u its almost a god sent to be able to tell the cam when to stop focusing by this method. Rather than letting the cam decide when to start or stop AF tracking, u can control by releasing and depressing the AF-On as and when u wish. humans r still smarter ur hit rate should increase dramatically, with proper panning technique in place, to 80%. it takes a while to really understand and appreciate the AF functions. it can be really frustrating or a god sent depending on how u use it. n usually for sports, one would prefer at least a monopod to plan. no fun with kilos on urs arms.

i had to read your post twice before i really understood it, but i must say after using cameras for close to two years, this is one of the more significant info i have learnt recently. Those af-on buttons were obviously created for a purpose, and i just never figured out what it was...till you put it into my head. It totally makes sense now!! THanks bro!

If you do have the 3D tracking function available to you, when do you then, make use of it?

[Jeff]

Originally Posted by tanjonhan i had to read your post twice before i really understood it, but i must say after using cameras for close to two years, this is one of the more significant info i have learnt recently. Those af-on buttons were obviously created for a purpose, and i just never figured out what it was...till you put it into my head. It totally makes sense now!! THanks bro! If you do have the 3D tracking function available to you, when do you then, make use of it?

i m still learning it everyday. there will be a rugby cup tomorrow at CCAB in the afternoon from 2:30 onwards. I'll be doing some experiments with newly conceived techniques and settings. hopefully i would be in a better position to answer that qn tomorrow.

[Jeff]

A continuation on the AF performance and settings can be found

http://www.clubsnap.com/forums/showt...hreadid=427099