Nikon Coolpix 7900 Digital Camera Review

Color (6.36)
We test the color accuracy of each camera we review using an industry standard GretagMacbeth color chart. We evaluated the Coolpix 7900’s color reproduction by taking several exposures of the chart and loading them into Imatest Imaging Software. The software program compared the 7900’s colors to the original colors on the chart and output some visual results as well. Below is a color chart modified by Imatest to show the color differences. The outer square of each tile shows the color produced by the Nikon Coolpix 7900. The inner vertical rectangle shows the original color of the chart. The inner square shows a modified version of 7900’s colors corrected for luminance.

These results are displayed again below, this time in a graph with only the ideal colors and the 7900’s colors. Each square on the graph represents an original tile from the GretagMacbeth color chart. The circles represent the Nikon Coolpix 7900’s rendering of the color. The line between the two unifies the colors and its length represents the degree of error. Longer lines indicate a greater degree of error.

The Nikon Coolpix 7900 performed a bit below average with an unremarkable 6.36 overall color score and a 9.44 color error. Many compact digital cameras exaggerate colors and the 7900 is no different; it over-saturated colors by 10 percent. Most models exaggerate the red #15 tile the most because that is the color that enhances Caucasian skin tones. Surprisingly, this color is only slightly embellished compared to the cooler tones. Overall, the Nikon Coolpix 7900 doesn’t produce accurate colors but they do look vibrant because of the degree of over-saturation. If you are looking for a naturalistic rendering of the scene, some post-capture enhancement will likely be needed.

Still Life Scene
Below is a shot of our still life scene recorded with the Nikon Coolpix 7900.

Click on the image above to view the full resolution version (CAUTION: the linked file is very large!)

Resolution / Sharpness (2.9)
The Nikon Coolpix 7900 has a 1/1.8-inch CCD with 7.1 advertised effective megapixels on it. We tested the 7900 by taking several pictures of the industry standard resolution chart and uploading them into Imatest Imaging Software. Below is one of the images we loaded into the program, which then analyzed the picture for its resolution and sharpness.

Click on the chart above to view the full resolution image

Imatest’s analysis of this chart determined the limit where the 7900 couldn’t differentiate the lines from one another anymore. The result is reported in LW/PH, which stands for line widths per picture height. Traditionally, resolution measurements were reported in units of line pairs per picture height or LP/PH, but this does not apply to varying sizes of image sensors like those on digital cameras. Therefore, we use LW/PH to standardize results for cameras with different sized sensors.

Imatest detected 1.02-3.13 percent over-sharpening and 1464 LW/PH in the horizontal direction and 1430 in the vertical direction. To provide some context for these results, here are a few figures from comparable 7-megapixel compact digital cameras. The Canon PowerShot SD500 read 1862 LW/PH horizontally and 1952 vertically. The Sony Cyber-shot DSC-W7 read 1654 LW/PH horizontally and 1973 vertically. By contrast, the Nikon Coolpix 7900’s figures in the 1400s are not very impressive at all. Beware when cropping and printing large photographs.

Noise - Auto ISO (4.38)
When the ISO is automatically set using the Coolpix 7900, noise levels are decent – not low and not high. The Nikon Coolpix 7900 received an overall automatic ISO noise score of 4.38, which is slightly below the average score most compact models receive. During our testing, the 7900 recorded the same amount of noise when the ISO was set automatically and when the ISO was set manually to ISO 80.

Noise - Manual ISO (3.78)
Ninety-five percent of the time, digital cameras produce less noise in general when the ISO is set manually. The Nikon Coolpix 7900 is in the other five percent. We tested the noise levels at each manual ISO setting and ended up with an overall score of 3.78. This is after testing with the noise reduction mode both on and off. Below is a chart showing the ISO ratings on the horizontal axis and the noise levels on the vertical axis. The red line represents the noise level when the noise reduction mode is off and the blue line represents the camera’s performance when it is activated.

Judging from the above chart, it looks like the noise reduction mode is relatively useless. When the noise reduction is activated, other image parameters are affected. The saturation fades from 110 percent to 109.6 percent and the color accuracy declines from a 9.23 color error to a greater 9.44 error. This is nothing terribly drastic, but worth noting.

Low Light Performance (4.5)
Be wary when shooting with this camera at night or even in dimly lit rooms; the Nikon Coolpix 7900’s slowest shutter speed of 4 seconds and the top ISO of 400 certainly aren’t conducive to night photography. To test the camera’s low light performance, we recorded a sequence of shots of a GretagMacbeth color chart at decreasing light levels. Lux levels of 60 and 30 are fairly common low light scenarios; 60 lux is roughly the amount of light in a living room with two soft table lamps and 30 lux equates to the illumination emitted from a single 40-watt bulb. We also tested the Nikon 7900 at 15 and 5 lux, which are both nearing darkness.

Low Light Tests
60 Lux	30 Lux
15 Lux	5 Lux

None of the images turned out spectacular in low light. The images are grainy and colors are muddy, with a notable drop in illumination occurring between 15 and 5 lux.

Below is a chart showing the noise levels in low light. The vertical axis shows the noise level and the horizontal axis shows the exposure time in seconds. There is a substantial leap in noise in exposures that are longer than one second.

Speed / Timing
Start-up to First Shot (5.79)
The Nikon Coolpix 7900 is a bit slow off the starting line with its 4.21-second start-up time. So power up the camera and take a long breath of air; it’ll take a few seconds to boot up for its first shot.

Shot to Shot (9.31)
The 7900 has average speed and above average endurance. This Coolpix took a sequence of 19 shots with an average of a shot every 0.681 seconds.

Shutter to Shot (8.38)
The amount of shutter lag depends on the auto focus system’s reaction time to the subject. In low light the Coolpix 7900 will take a tiny bit longer to focus than in optimal light. When the digital camera is shooting in good conditions, it takes 0.31 seconds to grab the shot.