Some of you pixel peepers out there may have noticed your images are soft and not focused as well as they should be. Our cameras have fantastic auto focusing systems nowadays so honestly why does this happen?
This is something I was having trouble with some time ago when I bought my NIKON D7000. Up until that point I had been using the entry level NIKON D3100 , my first DSLR camera, and as a noob to the game I didn’t pay much attention or pixel peep as much as I do today, so these focusing errors were not of huge concern and were going unnoticed.
As I progressed in my photography I started uploading to Stock sites and was getting many many rejections to my images, I would say at the beginning over 95% were being rejected for “soft or blurry” images. It was very disheartening, as to me my images looked great but when people are buying Stock they want the best images out there so I had to learn what was causing this and find a way to rectify it.
Well there is a way to do this, we need to calibrate our lenses through the Af fine tune menu option on our NIKON bodies, Canon bodies have a similar option (Af micro adjustment) Not all bodies will have this option i.e entry level camera bodies will not.
Just a point I’d like to add is that this only works for using Auto focus through the Viewfinder , Live view Auto focus should be near perfect every time, I say near perfect as there are lots of other factors that could result in soft images, cheap lenses, dirty lenses, old worn out lenses and the like. If you are getting blurry out of focus images whilst using Live view then your lens will probably need sending away to get serviced/calibrated.
So how do I check my lens and calibrate using Af fine tune???
This is how I would check and adjust my Auto focus on my lenses.
First you need a tripod and get it setup somewhere outside in good light. Now find something easy to get the camera to Auto focus on i.e a stick or a garden cane or something like that and position it standing vertically somewhere say between 3 and 5 meters away. Now making sure your lens is set to its widest aperture and using the cameras central focus point , focus the camera using Live view on the stick and take a picture, this image if focused well as it should be will be our reference image. Now without moving the camera at all, check the image on the back screen and check it at 100% magnification for sharpness and focus. Now with the camera in exactly the same position take the same picture but use the View finder to focus and check it at 100% the same as before, Does it look good?? if yes then try it a few times to be sure. If it still looks good then you are good to go.
Now if the image was out of focus then we need to work out if the lens was front focusing i.e focused in front of the object somewhere, or back focusing which means it has focused somewhere behind our object. Sometimes this will be obvious, others, it will take extra scrutiny to work out which way the focus has gone.
Lets assume the camera was back focusing a little behind the object, then you would head into the Af fine tune menu and add a minus input into the adjustment to bring the focus forward (towards us) a bit (It would be the opposite for a front focusing error, i.e a + adjustment to push it away a bit). Try another test shot and check the image again, it should now be a bit closer to the object you are trying to focus on. If not head back in to the menu and repeat this operation and bring it back (towards us) a bit more until you get to the point where the object is as sharp as you can get with the lens aperture wide open. Once you find the correct point leave it there and you are done. Nikon cameras have a memory bank for several lenses so you can do this for all your lenses then when you switch between them it will remember which lens you have attached and revert to the correct setting accordingly.
I hope this little guide , although it sounds complicated (it really isn’t), can help you to get those pin sharp images that you all (like me) long for.