Any thoughts?

Bobby G

Bobby G

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Hi

A friend of mine is having a few problems and i wondered if anyone had ideas of what might be causing it.

The images below have the feet in focus, but the heads are slightly OOF; the focus point was set on the torso. It's a problem replicated in a high percentage of his sports shots and at times it can seem that points on the same focal plain have different results depending on where they are in the frame (front foot sharp, front hand soft etc). Both shot at around the 2,000th of a sec with a 70-200; one with a 40d the other with a 1D. My knowledge of Canon settings is nil but i can find out more details if required.

Anyone had a similar experience, or is he doing something wrong?

17005104526_4039bd981a_k by Bobby Gavin, on Flickr

16719161194_6b8a3807f9_k by Bobby Gavin, on Flickr

(Please move if this isn't the right forum for this question)
 
As a quick guess I'd say that a large aperture is giving shallow DoF, coupled with a very low camera he/she is falling foul to the Laws of Nature .... principally, Trigonometry! It's further to the face than it is to the feet! A running, leading foot is always going to be half a yard closer than the head - even without trigonometry playing it's part!
 
Is the whole person supposed to be sharp or just the face?

If just the face/upper torso then the focal point should be on the eyes and have a smaller f number i.e. f/5.6.

If it's the whole body then you're probably looking to have the aperture at around f/11 which will affect the shutter speed and will need to be compensated for with ISO if you want to keep the shutter speed high. Still focusing should be on the face for a person/animal and nowhere else IMO. 2000th of a second for shutter speed might be excessive considering the maximum length of the lens is 200mm and the subjects are running towards us. You could probably get a good sharp shot at around 1000th of a second or less which would help with stopping down the aperture to f/11 without needing to bump the ISO too much.

Have they got IS turned on? Using a monopod too?

Another thing is the focusing system. Was it on AI Servo which is a continuous focus - it'll focus every time it senses movement instead of focusing once and then another half press of the shutter is required. It's just like AF-C on Nikon if you require a comparison.
 
As said, at 200mm (at large apertures) when subject fills the frame, your DOF is very small and you need to nail the focus on the head/eyes - not the easiest with sport. 1/2000th seems a very high shutter speed for this type of event, typically you would get away with 1/500th which would allow a smaller aperture and greater DOF. I only use f/2.8 when I have to (dictated by weather) as it it much easier shooting at f/6.3 or even f/5.6 so as long as the focus point is on the person, they should be in focus. Also auto ISO is indispensable for sporting events.
 
It's not a technical error, it's the lens.

Check list:

a) Is the back mounting plate loose? If so tighten it and retest.

b) Otherwise send te lens to Canon CPS or Fixation for realignment. One of the elements is out of position.
 
Thanks all for the comments, much appreciated.

The DOF & Focus points were our first thoughts but most of my stuff is shot at F2.8 on a 70-200 & 300mm, and I've never the had the problems experienced here. The biggest puzzle though was objects on the same focal plane being in/out of focus, which had us stumped; so I'll pass on the comments and let him take it from there.

Again, many thanks

Bobby
 
Bobby G said:
Thanks all for the comments, much appreciated.

The DOF & Focus points were our first thoughts but most of my stuff is shot at F2.8 on a 70-200 & 300mm, and I've never the had the problems experienced here. The biggest puzzle though was objects on the same focal plane being in/out of focus, which had us stumped; so I'll pass on the comments and let him take it from there.

Again, many thanks

Bobby
Click to expand...

Which is the exact symptom of one of the elements being out of alignment. Hence my suggestion above.
 
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