Focus problem I encountered today, and an interesting resolution
Discussion
3 replies
Posted by Bob Falcone on January 27, 2007 at 7:35 PM
You all may find this interesting (or not)...
I typically keep the focusing point of my DSLR (in this case a 10D) on the center focus point. A few days ago I got my BG-ED3 grip back form Canon for some repairs, and when I tried it out, I found that the camera had great difficulty focusing with the center spot. Changing lenses didn't make any difference, and neither did removing the grip (a long shot, but what the heck). I then changed the cameras focusing points and found that it focused fine on all points except the center point. This is quite the opposite of normal operation, where the center spot is typically the fastest and most sensitive focus point. Now I was really stumped, and wasn't looking forward to having the camera sent away for repairs. After mulling over the situation a bit, I had a "ah ha!" moment. I put the camera in "sensor clean" mode, pointed the lens opening down and blew out the cavity with a Rocket Blower. I put the lens back on, selected the center point and the camera started focusing as well as it ever did.
I imagine that some dust either got on the mirror, beam splitter or focus sensor in just the right place to severly cripple the center spot. So, if you experience this problem (or something similar) you may want to clean it before shipping it away for service.
Posted by Todd Caudle on January 28, 2007 at 1:48 AM
Great tip, Bob. I'm envious of the new Canon D-SLRs that are coming with an automatic sensor cleaner. I'll keep this in mind if the ol' 5D ever starts exhibiting the same problem.
Posted by Bob Falcone on January 28, 2007 at 12:36 PM
Same here, Todd. That one feature may push me to upgrading from my 10D a little sooner than I anticipated...
Posted by Ken Wyatt on February 4, 2007 at 2:01 AM
Speaking of cleaning systems, I purchased eFilm's new sensor cleaning microscope and vacuum while at the NANPA conference a couple weeks ago. The microscope really does work in revealing dust and other nasties on the sensor. The vacuum seems good at sucking up the big stuff and the "sensor swipe" clones work well at sweeping off the remaining particles. or the first time, my 5D came completely clean - and without repeatedly running outside to shoot the sky - then returning inside to examine the result by scanning the playback image in magnified view! We may finally have the ultimate cleaning system! It was quick and easy.
On the 5D, though, I found I had to pull the magnifier slightly away from the body in order to focus properly - not a big deal really.
Discussion
3 repliesI typically keep the focusing point of my DSLR (in this case a 10D) on the center focus point. A few days ago I got my BG-ED3 grip back form Canon for some repairs, and when I tried it out, I found that the camera had great difficulty focusing with the center spot. Changing lenses didn't make any difference, and neither did removing the grip (a long shot, but what the heck). I then changed the cameras focusing points and found that it focused fine on all points except the center point. This is quite the opposite of normal operation, where the center spot is typically the fastest and most sensitive focus point. Now I was really stumped, and wasn't looking forward to having the camera sent away for repairs. After mulling over the situation a bit, I had a "ah ha!" moment. I put the camera in "sensor clean" mode, pointed the lens opening down and blew out the cavity with a Rocket Blower. I put the lens back on, selected the center point and the camera started focusing as well as it ever did.
I imagine that some dust either got on the mirror, beam splitter or focus sensor in just the right place to severly cripple the center spot. So, if you experience this problem (or something similar) you may want to clean it before shipping it away for service.
On the 5D, though, I found I had to pull the magnifier slightly away from the body in order to focus properly - not a big deal really.
Ken