tag:blogger.com,1999:blog-2361251099864607419.post5740859184300407453..comments2024-03-18T01:15:17.741-07:00Comments on Better Family Photos: Canon 5D Mark II - AF Point Area Expansion Issue360 Rumorshttp://www.blogger.com/profile/01173469932778454315noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-2361251099864607419.post-19785386745419034182014-09-30T12:05:19.205-07:002014-09-30T12:05:19.205-07:00Hi Mohannad,
First of all thank you so much for t...Hi Mohannad,<br /><br />First of all thank you so much for taking the time to make such a detailed post and if you have got this far thank you for reading my reply. I too am a keen photographer and use the 5Dmkii, my favorite lens for action is the 70-200mm f2.8 zoom similar at the long end to your 200mm.<br /><br />I think I might have an explanation for the "front focus" issue on the 5dMkii.<br /><br />My understanding is that in expansion mode, We are effectively turning on more focus points. The camera will now focus on which ever is the CLOSEST out of all the 6 expansion points plus the original centre point.<br /><br />So in the book example the focus will shift to the lower points as they are closer. Hence it looks like it is "front focusing" it is actually just focusing on the closest of all the AF point.<br /><br />Getting back to shooting action. The AF in AI Servo mode is pretty accurate, but takes practice to keep on a moving subject. I personally tend NOT to use AF expansion. The reason is that I try to focus on a very small area following the old sports shooter maxim of "shoot small, miss small" which means try and have a very small area to focus on, and if you miss it miss it by a small amount.<br /><br />I try to get the central point aiming for the eye closest to the camera, a head if I cant track an eye, and a torso if I cant track a head. If I was to use AF expansion the focus might jump to another subject the tip of the nose, the hands carrying the ball or another player.<br /><br />One other thing to consider is DOF. At 200mm you don't have much DOF to play with, especially at closer ranges like 10 or less metres. If your subject is 10m away at f2.8 your DOF is just 32cm of which only 16cm is behind the point of focus. i.e. if you focus on the eyes everything beyond the ear is out of focus. This makes it hard on a moving subject. If your subject is at 10m using f5.6 will give you 63cm DOF or 33cm behind the point of focus just enough to get a full head and a full body of a running subject.<br /><br />There are lots of great free iPhone apps or tables on the net to help calculate DOF.<br /><br />Thanks again for the post and I hope my AF explanation makes sense.<br /><br />Best, Angus.<br /><br /> <br /><br /><br /><br /><br /><br /> ArielGuyhttps://www.blogger.com/profile/06757857878952520180noreply@blogger.comtag:blogger.com,1999:blog-2361251099864607419.post-66770885072627139322013-11-22T07:44:18.313-08:002013-11-22T07:44:18.313-08:00Thank you for your tests, it seems the effect is p...Thank you for your tests, it seems the effect is pronounced with longer lenses due to the compression effect.mshafikhttps://www.blogger.com/profile/09178862453786826299noreply@blogger.comtag:blogger.com,1999:blog-2361251099864607419.post-37608127354093461592013-11-22T07:37:14.393-08:002013-11-22T07:37:14.393-08:00A few refinments to the info....
I did the tests o...A few refinments to the info....<br />I did the tests on my 5D2 very carefully with tripod and mirror up, 2 second timer with 200mm lens at f4.<br />Did sets of 4 shots with focus arriuving from alternate infinity and closeup directions twice.<br />Center focus point selected with AI Servo mode.<br />I got the same results. I even tried with function on while jostling the trpod during focus aquistion to see if it worked with motion. It didn't - no difference. still front focus tendency.<br />My conclusion: the so called "expansion focus points" simply don't work and in fact even have a tendency to cause front focus problems. Amazing actually that Canon never adressed this with a firmware update! They never used this feature on any camera since should tell us something.<br /><br />I turned my expansion points off, never to be used again.<br />Very surprising but you gotta check everything. Never assume nothing. lol.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2361251099864607419.post-27581125152944554822013-11-21T14:42:01.525-08:002013-11-21T14:42:01.525-08:00I did the tests on my 5D2 very carefully with trip...I did the tests on my 5D2 very carefully with tripod and mirror up.<br />Did sets of 4 shots with focus coming from opposite extreme directions.<br />Single center point selected with AI Servo mode.<br />I got the same results. I even tried a set while jostling the trpod during focus aquistion to see if it worked with motion. It didn't - no difference. still front focus tendency.<br />My conclusion: the so called "expansion focus points" simply don't work and in fact even have a tendency to cause front focus problems. Amazing actually that Canon never adressed this with a firmware update!<br />I turned my expansion points off, never to be used again.<br />Very surprising but you gotta check everything. Never assume nothing. lol.Anonymousnoreply@blogger.com