Manual focus error

News Flash. 12/22/1999

This page is now pretty much obsolete. The new firmware 1.3 release FIXED THIS PROBLEM ON MY CAMERA COMPLETELY.  Hopefully it will fix other's cameras as well. I will leave this page up for others to use to identify the problem on their cameras, or to identify any lingering issues, if any, but the information should be considered out of date with the advent of the new 1.3 firmware.


The manual focus settings for the CP950 are incorrect for wide angle and zoom telephoto settings ON SOME BUT NOT ALL CAMERAS. This now appears to be a consequence of performing one of the availible firmware upgrades. Starting to get reports from people who have upgraded, but do not have the problem. (updated 12/22/1999)

You may want to skip down to the discussion section at the end of the page and start there if you are new to this issue.

Jump right to the focus survey results! Last update Dec. 11, 1999


Focus distances on my camera with 1.1

In the following table, I have measured the actual focus distances against the manual focus settings. This was done after the 1.1 upgrade on my camera. A quick check shows that the distances are the same after the 1.2 upgrade.

Distances are in feet. The TELEPHOTO and WIDE ANGLE colums show the measured focus distances.


0.33                     0.27                     0.83

0.66                     0.50                     1.08

1.0                        0.75                    1.16

1.5                        1.21                    1.75

2.0                        1.54                      -

3.0                        2.25                    4

5                          3.2                      5.5

10                         4.5                       10?

30                         5.5                       infinite?

infinite                   9                          infinite?



   I could not judge the focus on the more distant wide angle shots very well. I used wide open aperture to maximize depth of field. I made this table by photographing chalk marks on the ground for the more distant settings, or by using a ruler for the closer observations. I tried to visually estimate the center of the focused area. It would be possible to do this in a more controlled manner, but I feel that these results are pretty good.


   Well, you should check your camera for the problem, and if it has it you should not rely on the manual focus distances at all, especially for the telephoto setting. Note that on the infinity setting, my camera only focuses 9 feet away! Try this with your camera! In the real world, you will probably use less than the maximum aperture, and the depth of field might make the infinity setting usable. It would be interesting to compare other indivdual cameras to see if this is just a problem with my camera or with all of them. It is my opinion that the problem got WORSE with firmware 1.1. Automatic focus still works fine for my camera. My camera was adjusted and cleaned by Nikon a few days before I took my test shots for this table.

It is hard to see how the manual settings can be used at all, since the error is usually larger than the depth of field at maximum aperture. The settings are only accurate at one zoom setting that you can only estimate..

As you can see, the distances shown are too long for the telephoto settings,. and too short for the wide angle. There appears to be a middle setting where the distances are very close to correct.  I'm guessing by interpolation on the chart that I drew that this zoom level is about 45 mm; close to 50mm. I suppose that you could carry a little correction table around with you, but in my opinion that is the camera's job.

Before you ask, the 9-10 foot focus distance at telephoto infinity has been confimed by Denny Cannon with his 950, so it is not just something wacky with my camera. Try it with yours! If yours focuses at at different distance, let me know.

Take home lesson:

Check your own camera. If you have the problem, you should never use the infinity setting for telephoto shots, especially at maximum aperture where the depth of field will be the smallest. I have been burned by this in the past.. You can probably get away with it at wide angle.

Discussion of the problem


This next part is total speculation. Just my opinion. Here are some interesting facts... See the survey results below too!

1) The focus on my camera did change with the 1.1 firmware upgrade. INF focus worked in 1.0.

2) A user reports this scenario. He had 1.1, and bad INF focus. He sent the camera in to Nikon, who adjusted the camera to work (reportedly replacing the lens unit). The really weird thing is that his camera now worked at all focal lenghts, just like it should!

3) This user loaded version 1.2, and the focus broke again.

4) When I zoom my camera at INF focus, I can hear the camera changing focus also!

I speculate that... (11/28/1999)

* There is a focus table in the camera, which does specify where the camera should focus for different distances at differnt focal lengths. You can hear it focusing when you zoom.

* This table is held in EEPROM or NVRAM.

* It is unique to each camera, but is usually loaded with defaults. It can be adjusted at the factory, probably just with software, which is how they "fix" your camera if you send it in for focus problems.. This is similar to what is being done on other types of new equipment. For example, I had a ham radio HT (VX-1R) that had the squelch table for the different bands stored in EEPROM rather than have actual adjustments on the radio. If you lost your table... back to the factory! Someone finally came up with a generic set of settings that you could load in with third party software. Very similar to this situation. One of the recommendations was to use the thrid party software to write down your radio settings in case you lost them later.

* Firmware upgrades could be overwriting these camera specific tables with a default table. (explains the focus change on my camera and others between version 1.0 and 1.1, and the user above that had his camera adjusted at the factory but then ruined again by the 1.2 upgrade. It also explains why the fisheye lens focus is breaking for some users when they upload new firmware.

This is total fantasy, knowing Nikon, but wouldn't it be great if they released the software that let users adjust their focus tables themselves? How are they going to fix this if each camera is adjusted differently at the factory? Are we all going to have to send our cameras back in to be recalibrated, and is the next upgrade just going to write in a default table again?


Survey Results

I started a thread on Steve's Digicams to survey the problem. Here are the results. (some of the information is missing/incomplete for some reports) You can e-mail me your results to add to this table if you like! Include the following info...

a) when did you get your camera. (some thought just early ones affected)

b) What firmware now.

c) did you ever upgrade the firmware.

d) your impression, did it used to work then broke, never worked, never broke?

* If you want to, estimate the focus distance at full zoom and INF. Mine is 9 to 10 feet.
* Any other interesting stuff!


On December 2nd 1999, I started a thread on Steve's stupendous discussion board about this problem. Here is a summary of the results so far. I've started each users experience with a "*".

* BB Purchased in Apri 12 with 1.0l. Manual focus worked with 1.0. Broke with 1.1. Still broken with 1.2. INF telephoto focus is 9-10 feet.

* JK Purchased in June. (Had 1.1?) focus broke with 1.2 install.

* "I" Focus broke with 1.2 install.

* MK Purchased in November.  Camera came with 1.2. Focus works.

* JK Purchased in March with 1.0.  Broke with 1.1 install. Still broken with 1.2. INF telephoto focus is 9 to 10 feet.

* FK Purchased with 1.0. Focus broke with 1.1 install. Repaired at Nikon service to work with 1.1! Focus broke again with 1.2 install.

* AL. Purchased April with 1.0.  Focus broke with 1.1 install. Still broken with 1.2 install. Focus distance at INF zoom is abotu 10 feet.

* RA Purchased in August (with 1.0? worked then?). Upgraded to 1.1 then 1.2. Not in focus at any distance now with INF telephoto.

* TP Purchased in May. Upgrade to 1.1 broke focus. Upgrade to 1.2 made it worse. Not in focus at any distance with INF telephoto. Now in for repair.

* "HC" Purchased June with 1.0. Never upgraded. Focus works.

* JM Unknown purchase. May have been OK with 1.0.  First noticed problem with 1.1. 1.2 no change. INF telephoto is in focus, wide angle is wrong, 0.7M setting focuses at 2.5M at wide angle. Repaired by Nikon calibration.

* Curtis. Purchased 4/99. Upgraded 1.0 to 1.1 to 1.2. Now out of focus at INF.

* WC. Upgraded to 1.2. Does not have the problem. I have seen sample shots.

* HB Upgraded to 1.2. Does NOT have the problem, his sample shots are fine.

* JS Purchased August 1999 with 1.1 Upgraded to 1.2, no focus problem

* TT. Focus was OK with 1.0, is now bad with 1.2. Infinity focus is at about the 5 foot setting.


Survey comments:

It sure looks as if the cameras are shipped working from the factory, and the problem correlates with installing either the 1.1 or 1.2 firmware upgrades. Not all cameras are affected, and my survey probably attracts the "squeeky wheel" type of report, and is biased towards reports of problems.  The exact nature of the problem seems to vary from camera to camera, but the most common is out of focus at most settings, and INF telephoto focusing at about 9-10 feet. The problem is consistant with overwriting an internal calibration table with the firmware upgrade, or with a firmware bug.

How Nikon is going to fix this is not known. The exact number of affected cameras is not known; on the Nikon tech BBS they have said 10%. An awful lot of cameras have been upgraded by now! If a significant percentage of them have to go back to be recalibrated, that will be a costly mess (just their shipping charges on returning all the cameras could be a lot of money). My suggestion is that Nikon do one or all of three things, and do it quickly before their service department is overwhelmed.

1) Release a "fix" for the "average" camera that will be "pretty good" for most cameras, with emphasis on the INF setting. The average camera seems to have INF telephoto focus at 9-10 feet after the upgrades, which makes me think that an average soloution could be developed.. This might hold a lot of users over. Only people with problems would install the fix.


2) Release several versions or tables that people could try to match common factory calibrations.


3) Release software that allows users to calibrate their own camera tables. This would be the best solution if it is possible Also the least likely based on past Nikon actions.


4) Hire (a lot) more people to handle all the cameras coming back for service!

Less satisfactory solutions include...

5) Ignore/deny the problem.

6) Promise a solution then delay as long as possible until cameras are out of warranty.


Obviously, not everyone will notice the problem, or will care even if they do have it. I have been living with it for months, it is just a matter of knowing when it will occur and working around it by using a different setting. . A lot of vacation shots will be ruined by people trying to use the INF setting. Let us hope that future versions of the firmware at least do not have this problem. The really annoying thing is that this problem started months ago with version 1.1. I reported it a few days after upgrading. It has only recently started to snowball into a big problem, but has been there for a while; it is not new with version 1.2. Unfortunately, most cameras have been upgraded from 1.0 by now, and will have the problem.

   I will probably send my camera in eventually to be calibrated. I am sort of waiting to see what the real cause is and what will be done about it; I don't want to send it in and then have to send it back again when the next firmware upgrade comes out.



A very interesting posting by Juri Munkki. He writes...

 " I called Nikon here in Finland and it turns out they were only a 20 minute train ride away. They were also willing to give me warranty
service even though the camera was bought from the USA and it is an NTSC model. I went there and they calibrated the focus system
while I waited and watched.

The calibration is done by putting the camera on a small tripod and pointing it at a resolution target that is exactly 1.5 meters away. The
camera is then connected to a PC and a calibration program is run from the PC. The camera LCD is on during the calibration process and
shows the camera zooming and autofocusing on the target for about a minute or so.

The whole thing takes less than five minutes.

After the calibration, manual focus is much more accurate at most zoom settings. At the very widest angle setting, the 10 cm focus setting is
still pretty far away (30-40 cm), but there's something odd going on, because changing the zoom even slightly will make the camera adjust
focus and bring sharp focus to around 15 cm, which is good enough for me. At maximum zoom, focus is still spot on correct at 10 cm.
Usually at this close range, I just use macro and rely on autofocus.

Infinity focus now works at all zoom settings. No complaints there.

Most importantly, if I have the camera set to wide angle and it's too dark for it to autofocus, it will now take a sharp picture if the subject is
within the reach of the flash. This is because when the camera can not focus, it will use a preset focus distance, which in my case used to be
very far away, but is now at a very convenient range.

If you have a chance to get your camera calibrated, I highly recommend it, if it's exhibiting any serious problems. The easiest way to test it
is probably to take a flash photo in a dark room where the subject is about 2-3 meters away. If all you get a is a blur, then your camera
may need adjustment. "


A new msg on the Nikontech board indicates that this issue will be addressed in the next 1.3 update. It is not clear if the update will fix cameras with the problem, or if those cameras will still have to be sent in. Stay tuned!