jonathan_lambert Posted November 18, 2015 Share Posted November 18, 2015 <p>I am using this lens on a 7D with center point, AF button on and AI servo, aperture 2.8 and with basketball shots sometimes their jerseys or the ball is sharp but their face will be soft or the complete opposite problem if their face is sharp. Is this a depth of field issue shooting at 2.8 or is there something wrong with my lens? I used to shoot with a 80-200 2.8 and never had this problem. </p> Link to comment Share on other sites More sharing options...
LenMarriott Posted November 19, 2015 Share Posted November 19, 2015 <p>Johnathan, What was the shutter speed? Could account for some softness throughout. Best, Len.</p> Link to comment Share on other sites More sharing options...
jonathan_lambert Posted November 19, 2015 Author Share Posted November 19, 2015 <p>Shutter speed is not issue, always 1/500 or faster. I use this lens to shoot football warm ups and it's outdoors with speeds at like 1/2000 and same problem. </p> Link to comment Share on other sites More sharing options...
parv Posted November 19, 2015 Share Posted November 19, 2015 The photo attached shows the letters on sleeveless shirt to be in plane of focus. That would be for the letters provides the most contrast for autofocus to, well, auto focus. Keep the most important point -- be that face, ball, clothes -- in focus as subject is moving. Yes, at f/2.8 not everything would be sharp enough due to lack of depth of field. Mind that DoF is also affected by the distance from the subject: closer the subject, lower the DoF. Link to comment Share on other sites More sharing options...
craig_shearman1 Posted November 21, 2015 Share Posted November 21, 2015 <p>Very nice shot but you (or your AF system) focused on the letters on his jersey not on his face. Focus always has to be on the eyes. That's why you can't rely on the camera to pick the right AF spot to use. You need to constantly be sure that you're choosing an AF spot that is on the eyes of the subject. At 2.8 there is very little depth of field, so focusing on the player's chest, arm, etc., isn't enough to cut it.<br /><br />Different cameras have different levels of sophistication in automaticaly or semi automatically choosing with AF spot or groups of AF spots to use. I don't trust mine and generally choose the spots manually. It means a lot of fingers flying around sometimes but gives me more consistent results.<br /><br />Can't explain why you got better results with the 80-200. Maybe a different body back then?</p> Link to comment Share on other sites More sharing options...
William Michael Posted November 25, 2015 Share Posted November 25, 2015 <p>I agree that the letters on the shirt are in the plane of sharp focus.</p> <p>If the player is about 6ft tall and that is an un-cropped image taken at F/2.8 on a 7D, then the DoF will be about 15 inches.</p> <p>I disagree that shutter speed is <em>not</em> an issue: there is definitive trailing edge movement blur to indicate that the ball and the left hand is moving vertically and the right hand is moving horizontally.</p> <p>Although difficult to ascertain definitively, because of the dark skin, it appears that the head is moving horizontally as there appears to be trailing blur in the teeth and also the eyes which matches the (camera left to right) movement of the right hand, but the head is not moving as quickly as the right hand: that would make sense.</p> <p>Although 15 inches or thereabouts is not a very large Depth of Field, certainly the Subject Movement Blur is exacerbating the out of focus appearance of the hands and most likely also the face.</p> <p>Considering the evidence of movement blur in the right hand and supporting supposition of movement blur in the face, it is not a very long stretch to assume the torso might also be moving from camera right to left (though at a slower speed than the face), in which case the letters on the shirt, although in the plane of sharp focus, might not be a sharp as they otherwise would be if the shutter speed were faster. </p> <p>WW</p> Link to comment Share on other sites More sharing options...
Gary Naka Posted October 2, 2016 Share Posted October 2, 2016 <p>Zoom OUT and put the center focus sensor on the FACE.</p> <p>I feel this is a problem with AF. People forget that they have to put the active AF point on the FACE.<br />On my cameras, I stopped using dynamic AF, as I did not know which AF sensor the camera was going to choose to focus with. And when it chose the wrong sensor, it could be too late to change it, the shot is lost. Single point, on the Center sensor made sure that I knew where the camera was going to focus. Anything else was worse than going back to manual focus lens, because with MF, I KNEW where I was focusing.</p> <p>However, I also recognize that in shooting FAST moving sports, it can be hard to keep the center sensor on the face, as you are tracking the action, not the face. This is why I would zoom out, so it is easier to track the face with the center sensor.</p> <p>A long lens at close distance will give you a shallow DoF at f2.8.<br />The face, jersey and ball are all at different focus planes.<br />If you want everything in focus, you need more DoF and thus need to use a smaller aperture, or pull back to a shorter focal length, where the same aperture will give you more DoF.</p> <p>The other question is you. Are you doing your part to hold the camera still and track the subject with the active AF sensor. Because your statement of having the same problem shooting football in daylight at 1/2000 sec concerns me. If you are on the sidelines, and the players are on your side of the field (IOW close to you), the DoF with a 200mm lens can be pretty shallow.</p> Link to comment Share on other sites More sharing options...
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