You just bought a new DSLR and you just can’t wait to start shooting great images. But wait, there’s a problem. Your camera somehow can’t seem to lock focus where you want it to. You’ve selected the right AF point and you paid attention when the exposure was made, but your camera always seems to focus just short of the subject. If you’re wondering if your camera’s broken, relax. This is a common problem, and John Greengo has a solution:
A situation where the camera tends to focus in front of the intended point of focus.
A situation where the camera consistently focuses behind the intended point of focus.
How to Fix Your Focusing Problems
Your camera needs to be recalibrated to adjust the focusing error. Back in the days when focus adjustment kits were not that readily available, you would have had to send your camera and lenses to an authorized service center.
Thankfully, this can now be done safely at home using the AF Fine Tuning (Nikon) or Microadjustment (Canon) option on your camera.
You’ll just need the following:
- A focusing target
- A ruler (to measure how much the camera is front focusing or back focusing)
You can buy a focus adjustment kit that has both, like the Lens Align Mark II, or if you are a maker, you can build one at home using a yardstick and a ruler. The ruler becomes your focusing target and the yardstick gives you an indication by how much your camera is off. The trick is to look at the point on the ruler which is tack sharp (compared to where you had focused) and compare it with the corresponding point which is next to the yardstick.
How to Test & Recalibrate Your Camera
- Set your camera on a tripod.
- Make sure that your camera does not shake during the test. If you have a cable release now would be a good idea to use it.
- Set your camera to aperture priority or manual mode.
- Set the lens to the widest aperture possible.
- Use the lowest ISO number you can.
- Set your camera on auto focus.
- Lock up the mirror.
- Shut off vibration reduction and image stabilization.
- Manually un-focus the lens. Then, allow the lens to acquire focus. Take the picture.
- Check the results of the test shots to see if the images are sharp where they were supposed to be.
- If the focusing is off, go to AF Fine Tune (Nikon) in your camera menu (check your manual to find the option for your own camera) and adjust the focus to make it either focus in front or back depending on how much and in which direction it is off.
This technique is really useful for lenses which have a wide maximum aperture, such as f/2.8 or wider. If you have a lens that stops only to about f/4.5 at its maximum, then even at its widest aperture the images will have a reasonable amount of depth of field, and thus they will not be much affected by any front or back focusing issues.
So, before you freak out and rush off to buy a new camera, try micro-adjusting your focus with this test. It might just do the trick—and save you a whole lot of money.
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