Error 99, interesting symptoms

[bstajc]

Hi guys, recently I started to experience error 99 with my 400D.
In my case, it coincides with me starting using the Focus confirmation chip on one of my lenses (I am not saying this was the cause.. I am just saying, the error started to appear after I put that thing on the camera).
The symptoms are interesting, as follows:
After re-installment of the battery, I can do 4 shots, no problems. After 5th one, I have error 99 on screen, which can be cleared by re-installment of battery, and then we go again.... 4 shots OK, 5th one comes with error, and is never saved on the card.
The pattern is repetitively occurring, regardless of any lens being on camera or not, with or without a CF card present.
Camera is relatively new, it took 3500 images.
However, some images taken with focus confirmation circuit have the upper part underexposed, which suggests some problem with the shutter.. but only with confirmation chip and only with short exposures... Also, there were other strange things happening when confirmation chip was present, like occasional all focus LED ON, beeping without pressing button etc..

I updated the firmware with the latest version available, I also checked the condition of both batteries...
I took the camera to canon service and they confirmed it was shutter. They replaced it with the new one and the problem was gone.
However, they could not explain the abovementioned behaviour (4 shots, 5th with error after re-installment of battery, with or without lens, and bad shots with confirmation chip).
I wonder, if was actually a software problem? Would it be possible that somehow som eparameter table in memory was corrupted by usage of focus confirmation chip? After replacing of the shutter, they had to re-calibrate the camera in which case parameter table was flushed and written over with correct data..
Anyone has similar experience?

[Bob Atkins]

I've heard of some people having problems with adapters containing the AF conformation chip, but I've never had any issues myself. I've used a "confirmation chip adapter" on a 20D, 40D and 5D with no problems at all (so far).

Since there are a bunch of sources for the AF chip and on most adapters it's glued onto the mount there's room for problems I guess. You could have a bad chip, or it could be in the wrong position and either short out or miss the connector pins in the camera body.

The problem is that these things are probably assembled in someone's garage in Russia or China and so there's really no quality control on them and getting a "bad" one is always a possibility.

Did you try the focus confirmation chip after you had the camera repaired, or did you take the safe route of not using it again?

[bstajc]

Hi Bob,
I just had the camera back from repair, and at this moment I decided to take the "safe route". I am using this camera almost exclusively for astro photography and I need it at this moment (because od comet Lulin)
This is why I post this, hoping that maybe there are other experiences like mine....
However, since I have warranty on parts (new shutter), I will try again in the near future.
I mounted the chip on adapter myself so there were no problems here.. contacts were spot on, and there were no shorts..
The lack of report like mine indicates that most likely the shutter failure has nothing to do with confirmation chip.