Coolpix 4500 "Ring" Problem Examples

The problem is the superimposition of a large number of concentric rings on the image.

Example 1

A number of setups were tried, in an attempt to isolate the problem. Links are provided to example pictures for each setup. Be aware that the full size files are around 1.4 MB, whilst the smaller examples are re-sized to 400 x 300 pixels, and saved as lower quality JPEGS (between 20 and 30 K bytes) for faster loading.

Note that the ring effect was observed on the LCD on the rear of the Coolpix, in addition to the computer screen.

Setup 1

This involved the use of a Brunel Microscopes "Digimount" adaptor screwed into the front thread of the Coolpix and placed in one eye piece socket of a Zeiss Ultraphot 2 in place of the normal eye piece. The zoom was set to the telephoto end (but did not employ digital zoom). Exposure and focussing were automatic in the Program mode. Image quality was "Fine". The microscope had been carefully set up for proper Kohler lighting. The objective was a Zeiss Plan x40 na 0.65. Example 1 (above).

Click here to open the full size file as saved in the camera.

Setup 2

This was similar to Setup 1. The only difference was that the Coolpix was held adjacent to a Zeiss CPL eye piece rather than employ the Brunel adaptor. Since the "rings" are very similar, it seems safe to eliminate the Brunel Adaptor as a possible source of the fault.

Click here to open a re-sized (smaller) picture of this example.

Click here to open the full size file as saved in the camera.

Setup 3

This was similar to Setup 1, but was on a Brunel SP10 microscope rather than the Zeiss, and used a Zeiss Planapo x 40 na 0.95 Objective. The lighting on the SP10 is not Kohler, although an Abbe condenser is employed. This would tend to eliminate any artefacts of the illumination system from contention.

Click here to open a re-sized (smaller) picture of this example.

Click here to open the full size file as saved in the camera.

Other information:

The rings stayed exactly in the same place relative to the camera field when the microscope stage was moved. That is they did not move with the slide. This eliminates any possibility of the rings being present in the mounting arrangements for the slide. In any case, similar rings were observed while observing other slides.

Click Here for an example of a different slide, also exhibiting the rings. The objective was a X6.3, and at this magnification the effect is less obvious.

The effect is seen at most zoom settings, but not at the extreme "wide angle" end of the setting. however, at this setting there is severe vignetting, so this is not really a solution.

It is sometimes possible to reproduce the effect by pointing the adaptor (fitted to the Coolpix, but not to a microscope) at a bright light source. Similar rings were seen. A comparison with a different 4500 in the shop where the camera was purchased seemed to indicate that the shop's demonstration coolpix did not exhibit the phenomenon. (But the conditions for carrying out this test were not ideal.)

When a Coolpix 950 is substituted for the 4500, the effect is not seen.

Click here for an example of a similar photo taken through a Coolpix 950 (re-sized) and here for the full size version.

With more "fussy" slides, where the contents cover the whole of the field of view, the effect is not obvious.

Click here for an example of such a slide, again taken using the X 6.3 objective, and here for a full file size version of the picture.

The effect has not been observed when using the Coolpix 4500 for more conventional photography.

I have spoken to Brunel Microscopes who use their adaptor with both Coolpix 950 and 4500 cameras and have not observed the phenomenon with either camera, despite extensive use under a number of conditions.

An initial conversation with the Nikon Technical support suggested that the reason that the rings were not visible on the Coolpix 950 pictures was because the number of pixels is less. At least, a direct comparison of the two cameras is not possible because of the difference in the number of the pixels. This did not seem very plausible, and in any event I have since come across an example of the effect on a Coolpix 950.

A member of the Queckett Microscopical Club recalled having seen or heard of a similar effect, the cause of which was isolated to mis-aligned optics in the camera.

The possibility of flare has been considered. If it is flare, this would indicate a fault with the camera (since the optics are very similar to those of the Coolpix 950). In any event, when observing the rings whilst pointing the camera at a strong light (with the adaptor fitted) the rings do not move position on the LCD screen when the camera is moved.

My own diagnosis is that the effect is a manufacturing fault in connection with the CCD sensor in the camera. There is no obvious reason, however, why I have not been able to observe any effect when taking more conventional photos.

Recent contact with Nikon UK (microscopes division) has come up with the possible diagnosis that the problem is Newtons Rings occurring at the interface between the CCD sensor and the protective plate in front of this. To ensure good photomicrographs, they tell me, I need to purchase one of their more specialist cameras!