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Old Jun 26, 2010, 10:48 AM   #1
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Default Possible Design Fault with Nikon D300 When Taking Long Exposures in Daylight

I have recently been taking long exposures with my D300 using a 10 stop ND grad filters in bright daylight conditions and have noticed a strange blue artefact appearing on the top left hand side of the image. Initially I thought it was lens flare or an effect created by the 10 stop ND filter.
But after extensive investigation I found that light is entering the camera body via the AF assist lamp and getting onto the image sensor and this is the reason for the blue artefact!
The image below was deliberately composed so that a dark background was present on the image where the blue artefact is located and it can clearly be seen in the top left on the image below:
I then covered the AF assist lamp area on the D300 body and took another image which is shown below which clearly shows the artefact has disappeared:
I have found that the shape and colour of the artefact is a function of brightness of the ambient light and length of exposure but it is always in the same location on the image so I have developed a simple test for other D300 users to try to confirm if the problem is as wide spread as I suspect. It occurs with all lens I have tried but does not occur on D90, D3000 and D40X bodies which I have tested.
Test Procedure
1. Set camera to Manual Mode.
2. Set Shutter speed to 30 seconds.
3. Set Aperture to F16.
4. Switch Lens to Manual operation.
5. Mount the camera on a tripod or stable surface outside in bright sunlight.
6. Ensure the Lens Cap is present and securely located on the end of the lens.
7. Press shutter release Ė wait 30 seconds and examine the resulting image.
The image below is from my D300:
Now repeat the test but cover the AF assist lamp area of body with black electrical insulating tape or your finger and you should correctly see a perfectly black image like the one below:
I have reported the problem to Nikon Europe and they responded back with the following statement:
Nikon Europe Support
18/06/2010 | 04:04 PM
Dear Adrian,
Thank you for your reply.
We have conducted a series of tests on a number of D300 bodies and have been able to replicate the issue. It seems that the optical connection between the AF illuminator and the imaging sensor has to be investigated by our engineers. Therefore I will have to escalate the incident to Design & Quality department.
Meanwhile, we suggest that you send your camera directly to our Service Department for testing and possible repair, however we cannot guarantee the solution can be found at this stage. Please note that the turnaround time is generally between 2 and 4 weeks - depending on part availability, testing requirements, etc.
We apologize for the inconvenience.
If you have any further queries regarding this matter, please click the link above to update your question.
Kind Regards,
Aleksander Nowak
Nikon Europe Professional Support
Receiving the above response from Nikon I decided to request that my D300 camera was exchanged for a D300S under warranty assuming that this did not have the same design fault as they stated they could not guarantee a solution could be found, I then received the following response:
Nikon Europe Support
22/06/2010 | 03:36 PM
Dear Adrian,
Thank you for your reply.
Further testing revealed that the cause of the light leak in our case was a physical damage to testing lens' mount and the problem cannot be replicated with another one or the body cap mounted. Also, the artifact looked different than on your samples.
Unfortunately, we cannot offer a replacement camera, as your issue seems to be an isolated one. We strongly suggest to have your camera serviced as per instructions in the previous e-mail.
If you have any further queries regarding this matter, please click the link above to update your question.
Kind Regards,
Aleksander Nowak
Nikon Europe Professional Support
I have now trawled the Internet and found the following links which show the same issue with the D300:
refer to Hammerhead64 item number 281
refer to devb (last but one comment) where he reported that it wasnít an isolated issue and his fix was to cover the AF assist lamp with tape.
refer to raoul_baartís comment at the bottom of the page with links:
Can all D300 users who read this please perform the simple test above and post the resulting images to the Forum assuming the same artefact is found on the images as I suspect and also report the problem to Nikon to prove itís not an isolated case as they suggest.
This problem may also be associated with the exposure problems in the sky area of images some users have experienced and reported in the Forum!
Thanks for your help,
Email: adrianlocke07@o2.co.uk
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