Auto Focus Fine Tune

[Peter Ryan]

I recently acquired a Nikon D300s (upgrading from the D70s) and I have had no end of problems with my old Nikor 70 – 300ED lens. I acquired this lens some 8 or so years ago for my old film body and really, really enjoyed it. It worked ok on the D70s but I couldn’t get a sharp image on the new camera. I kept thinking I must be getting old and having trouble hand holding the camera. I have messed up a number of shots I would have liked to keep.

I was about to update the lens and then remembered that the D300s has an Auto Focus Fine Tune to adjust individual lenses.

I tried it out on a focus test sheet I have and it was out by 20 mm. No wonder I couldn’t get a sharp image. The lessons, if you change cameras check the auto focus of all your lenses to ensure they are correct for the new body (if this facility is available on your new camera).

Both images below were processed the same in ACR with the same level of output sharpening. I have not added any other sharpening.

You can see that +20 (above the focus line) is quiet blurred in the first image but after adjustment there is about the same level of clarity on both sides of the focus line in image 2.

[MiniChris]

Is that an in-camera function? I wonder if the D7000 has it as well. I've noticed on several zoom images the focus isn't where I think it should be and I've done the dipoter change already.

[Peter Ryan]

Yes Chris, it is an in camera adjustment and in Nikons it is called Auto Focus Fine Tune. The chart is a separate item I copied from a photgraphy magazine. I have a copy and could email it to you if you want to try it. You can send me a PM with your email if you like.

[Nuno]

My camera does not have this function. I think if the auto focus is not right, it has to go to Nikon.
I could use a copy of your pattern too.

[benm]

This website has information on testing focus and adjusting auto focus even if you do not have the adjustment feature. I have never tried this myself so you are on your own. There is also a focus chart you can print out.

http://leongoodman.tripod.com/d70focusnew.html

If you do it I would be interested in learning the results.

[Peter Ryan]

My camera does not have this function. I think if the auto focus is not right, it has to go to Nikon.
I could use a copy of your pattern too.

Hi Nuno,

Ben has pointed you to another test sheet but I am happy to send you one if you send me a private message and include your email address.

[Peter Ryan]

This website has information on testing focus and adjusting auto focus even if you do not have the adjustment feature. I have never tried this myself so you are on your own. There is also a focus chart you can print out.

http://leongoodman.tripod.com/d70focusnew.html

If you do it I would be interested in learning the results.

Hi Ben,

I had a quick read through that and while very interesting they are suggesting you take a wrench to your camera. I think they assume if the auto focus is out on one lens then it will be on all.

I purchased a new lens with the camera (mid range zoom) and it focuses fine. It is only the older 70 – 300 that is out. I note my camera will hold specific fine tune adjustments for up to 12 lenses so it seems to be more of a lens compatibility issue rather than in holistic problem with the auto focus. When I fine tune a lens the camera automatically reads the lens when fitted and makes the necessary adjustment.

[benm]

Using an allen wrench inside the camera is not something I would attempt, hence my use of boldface. But I am perplexed about exactly what happens inside the camera when the MFA feature is used. Is there an actual physical change to some distance between components or is it strictly a software adjustment? And why might different values be needed for two identical lenses (the only difference being the serial number)?

[Peter Ryan]

Hi Ben,

I am ot sure whether it is a hardware or software adjustment but my camera holds up to 12 lens in memory and corrects accordingly when I attach them.

[Wirefox]

And for those of us with grown up cameras

EOS 40D, 50D, 5D Mark II, 7D, and 1D-series.

1. Mount the camera and lens on a tripod. If the lens has IS, shut it off.

2. Use Live View to manually focus on a stationary,flat, high-contrast object that is at the center of the viewfinder and parallel to the plane of focus. The camera-to-subject distance should be no less than 50 times the focal length of the lens. For a 50mm lens this would be at least 2.5 meters, or approximately 8.2 feet.

3. Focus the lens at its maximum aperture. Use Live View magnification if necessary to assure that the image is as sharp as possible.

4. Without touching the focusing ring or moving the tripod, turn off Live View, and return the camera to One-Shot AF, using only the center AF point.

5. Gently press the shutter button down halfway (or the AF button if using back-button AF) while observing the focusing ring or scale on the lens. It should not move. If it does, take note of whether AF moves the plane of focus closer (front-focus) or further away (back-focus). If there is no shift in focus your lens is well-calibrated and requires no adjustment.

6. To determine the correct amount of adjustment necessary, take three sets of images at micro- adjustment settings of -10 , 0 and +10; in other words, three consecutive images at -10, three consecutive images at 0, and three consecutive images at +10.

7. Examine the resulting images on your computer monitor at 100% pixel magnification.

8. Take additional sets of test images at different microadjustment settings if necessary until you can determine which setting produces the sharpest image.

9. Register the corresponding microadjustment setting in the camera.

[inkista]

And for those of us with grown up cameras

EOS 40D, 50D, 5D Mark II, 7D, and 1D-series....

Err... NOT the 40D. The 50D is the first (and only) of the xxD bodies to have AF microadjust.

[Wirefox]

Sorry you are correct CDLC literature is misleading.

Quote: "Note: This procedure applies only to DSLRs that have a micro-
adjustment feature, such as the EOS 40D, 50D, 5D Mark II, 7D, and 1D-series.)"

In fact 40D can only be adjusted by Canon tech. Others mentioned above can be done via on-camera menu systems