Constant AI Servo on 5d3?

[lexonio]

Hello everyone, I've been slowly moving toward primes lately (not the "I'm going primes because zooms are mainstream" kind of thing, I just like the shallow DoF and the IQ primes provide more at the moment).

The one thing that keeps bothering me is how shallow the DoF really is, and that brings me to a question - has anyone tried keeping AI Servo mode on while shooting with primes wide open? And if so, what did you achieve?
Thanks in advance.

[Mt Spokane Photography]

Thats my standard method, I use one shot when the camera is mounted on the tripod, or some other factor makes it better than using AI Servo.
 
Note: The camera is set to AI Servo in the green box mode.

[SandyP]

It depends. I only use AI SERVO when things are moving around, like at a wedding, or a concert. If I'm shooting portraits I see no reason to use AI SERVO at all. Plus, you can always stop the lens down to get more depth of field, you don't HAVE to shoot it at f/1.4 or f/1.2 ya know.

[lexonio]

Thats my standard method, I use one shot when the camera is mounted on the tripod, or some other factor makes it better than using AI Servo.
 
Note: The camera is set to AI Servo in the green box mode.

Green box? Fully Automatic mod?

[neuroanatomist]

With static subjects, I use One Shot. With my 5DII, I almost always use One Shot because of the disappointing results I get with AI Servo, regardless of lens.  On my 7D, if there's movement or expected movement, I use AI Servo.  Shooting with my 85mm f/1.2L II on the 7D in AI Servo, several times with young daughter running diagonally toward me, I got about 8 of 10 shots in crisp, eyelash-counting focus despite the 'ponderous' AF of the 85L.

I haven't used the 5DIII, but given that it bests the 7D on AF, I'd not hesitate to use AI Servo with fast primes wide open - I certainly will be doing a lot of that when my 5DII replacement - a 1D X - arrives.

[wickidwombat]

With static subjects, I use One Shot. With my 5DII, I almost always use One Shot because of the disappointing results I get with AI Servo, regardless of lens.  On my 7D, if there's movement or expected movement, I use AI Servo.  Shooting with my 85mm f/1.2L II on the 7D in AI Servo, several times with young daughter running diagonally toward me, I got about 8 of 10 shots in crisp, eyelash-counting focus despite the 'ponderous' AF of the 85L.

I haven't used the 5DIII, but given that it bests the 7D on AF, I'd not hesitate to use AI Servo with fast primes wide open - I certainly will be doing a lot of that when my 5DII replacement - a 1D X - arrives.

what focus mode ddo you use? zone? spot? i havent had such great results using spot and trying to maintain tracking of a persons eye walking towards me

[bdunbar79]

With static subjects, I use One Shot. With my 5DII, I almost always use One Shot because of the disappointing results I get with AI Servo, regardless of lens.  On my 7D, if there's movement or expected movement, I use AI Servo.  Shooting with my 85mm f/1.2L II on the 7D in AI Servo, several times with young daughter running diagonally toward me, I got about 8 of 10 shots in crisp, eyelash-counting focus despite the 'ponderous' AF of the 85L.

I haven't used the 5DIII, but given that it bests the 7D on AF, I'd not hesitate to use AI Servo with fast primes wide open - I certainly will be doing a lot of that when my 5DII replacement - a 1D X - arrives.

what focus mode ddo you use? zone? spot? i havent had such great results using spot and trying to maintain tracking of a persons eye walking towards me

On a 5D Mark III, it is a completely different ballgame than on a 1D body, such as the 1D Mark IV.  Since metering is always done through the center point regardless of chosen AF point, I use center-weighted average metering.  I set in Av mode, decide my aperture, which is usually 6.3 for indoor sports, set my shutter speed to 1/500, then set ISO to auto.  I shoot a few shots in real life situation then read the ISO reading.  Switch to Manual and program that ISO setting in.  If I begin missing, I set ISO back to A and maybe do an EC of +1/3 or +2/3 or simply raise or lower my ISO value with the click of button and the thumb-roll of a dial.  On the 1D 4 this isn't necessary, you can set it to Av, min shutter speed, and auto ISO.  5D Mark III takes a bit more work, but it can be done.

[te4o]

I don't understand why people always claim that on the 5D3 the metering does not follow the AF point achieving focus or pre-selected to achieve focus. Of course the camera meters at this AF point as long as you use it in evaluative mode. It's at the bottom of page 171 of the manual and I can confirm that. How comes that people always claim the opposite? Am I missing something? If you use spot metering or the other three then it goes through the center point only but evaluative follows the AF point achieving focus! Only on AF lenses though! And not in MF mode on an AF lens.
So, I use AI-SS switch over the DOF Preview button if I suspect movement. But if I focus and recompose a bit then AI is obviously not practical. On my MF ZE line neither But using AI with my 135/2 or the 85/1.4 S is just a great experience on moving subjects! It is tricky though to select the right AI mode on a 5D3. I'll open a new topic on that soon.
Cheers

[bdunbar79]

I don't understand why people always claim that on the 5D3 the metering does not follow the AF point achieving focus or pre-selected to achieve focus. Of course the camera meters at this AF point as long as you use it in evaluative mode. It's at the bottom of page 171 of the manual and I can confirm that. How comes that people always claim the opposite? Am I missing something? If you use spot metering or the other three then it goes through the center point only but evaluative follows the AF point achieving focus! Only on AF lenses though! And not in MF mode on an AF lens.
So, I use AI-SS switch over the DOF Preview button if I suspect movement. But if I focus and recompose a bit then AI is obviously not practical. On my MF ZE line neither But using AI with my 135/2 or the 85/1.4 S is just a great experience on moving subjects! It is tricky though to select the right AI mode on a 5D3. I'll open a new topic on that soon.
Cheers

Nobody claimed that.  Nobody said in all metering modes, but spot metering. 

[te4o]

OK, I misunderstood,  I appologize, bdunbar, I just have been coming across many threads with similar content and now decided to respond, sorry!

[bdunbar79]

OK, I misunderstood,  I appologize, bdunbar, I just have been coming across many threads with similar content and now decided to respond, sorry!

No need to apologize at all.  It is tricky and people have gotten it wrong.  My 1D Mark IV will do spot metering through the active AF point, my 5D Mark III won't.  That would be exclusive of other metering modes simply by how they work.  How can you do an evaluative or center-weighted average metering through an auto focus point?  You really can't; in that case the whole frame is taken into consideration, whereas the spot metering is a much smaller region (based upon that is), that could change throughout the frame, ie dark shadow vs. highlighted sidewalk. 

[neuroanatomist]

With static subjects, I use One Shot. With my 5DII, I almost always use One Shot because of the disappointing results I get with AI Servo, regardless of lens.  On my 7D, if there's movement or expected movement, I use AI Servo.  Shooting with my 85mm f/1.2L II on the 7D in AI Servo, several times with young daughter running diagonally toward me, I got about 8 of 10 shots in crisp, eyelash-counting focus despite the 'ponderous' AF of the 85L..

what focus mode ddo you use? zone? spot? i havent had such great results using spot and trying to maintain tracking of a persons eye walking towards me

Depending on the subject, either AF point expansion (the + pattern with 4 supplemental points on the 7D) for subjects I can track pretty well in the VF, or Auto selection (where in AI Servo, you designate the starting point for tracking and it then uses all 19 as needed to keep a lock) for very erratically moving subjects.

Spot AF doesn't work well for moving subjects (IIRC, one of Canon's technical write-ups advises against it, as well).

I don't understand why people always claim that on the 5D3 the metering does not follow the AF point achieving focus or pre-selected to achieve focus. Of course the camera meters at this AF point as long as you use it in evaluative mode. It's at the bottom of page 171 of the manual and I can confirm that.

Let's be clear, though. Evaluative metering is linked to the AF point selected (by you or the camera), but evaluative metering is not the same as spot metering.  Evaluative metering looks at all zones, and compares the luminance (and for some metering sensors, two-color or RGB color values) readings to a stored database of pre-programmed scenarios.  The final meter reading is weighted toward the AF point (degree of weighting is unknown and almost certainly variable), but the final reading comes from the whole scene.  That means a large bright or dark portion of the scene, or a subject that has a very different luminance that the rest of the scene can throw off the metering for the subject.  Spot metering ignores the rest of the scene, and when linked to the AF point as it is on 1-series bodies, is very useful.

The classic example is a bird flying across a blue sky - evaluative metering, despite a 'linked' AF point right on the subject, will give you a silhouette every time.