Image quality - related to camera or not? Blurry, artificially sharpened images

Question

I bought a D90 camera recently which was well used with 67k shutter actuations.

I took some photos and this is the result:

On the left, you can see that the image looks blurry when zoomed into, with a distinct look like it was almost badly, artificially sharpened by photoshop.

Is this a problem with the sensor? The lens? Or the settings? Same thing happens in RAW mode.

Camera: Nikon D90
Lens:   AF Nikkor 50mm f/1.8D
Shot at 50 mm (35mm film equiv: 75mm)
Exposure:   Manual exposure, 1/200 sec, f/2.5, ISO 2000
Flash:  none
Focus:  AF-A, at 1.0m, with a depth of field of about 3.8cm, centered on the focus point

AF Area Mode: Dynamic Area

Answer 1

You took this photo indoors, without a flash, in low light. The camera selected a high(er) ISO then would be desirable especially when "pixel peeping" at 100% on screen. If you would post an image to a website that does not strip the EXIF info, I could tell you more about this, but as it is posted on Imgur I cannot tell you what ISO was selected. Another possible issue could be the shutter speed, which could be so low as to introduce camera shake and lower the quality of the resulting image. All in all, the image was captured in less than favorable conditions, likely leading to not so great output. If you really want to test this camera/lens because it is new to you, choose a more favorable subject such as outdoors during an overcast day shot at f/5.6-f/8, ISO100, and on a tripod.

I would advise you take a look at the following questions for more information:

• How can I test a new lens to make sure it is operating correctly?
• How can I determine the minimum shutter speed to avoid blur from camera shake?
• How much "noise" is acceptable in a photograph?
• How can I/should I check the sharpness of my camera lens?

Answer 2

Your basic issue is that you expect viewing the image at 100% to look just as good as viewing it at more typical sizes. Your D90 has a resolution of 4288 X 2848 pixels. When zoomed in to 100% and viewed on a typical 96 dpi monitor, that equates to a total image size of 45" X 30"!

Even an image shot in plenty of light at a very fast shutter speed from a tripod mounted camera wouldn't hold up to such scrutiny. Your image also contends with the following issues:

• Low light resulting in a lower signal to noise ratio. This requires increased ISO sensitivity to obtain proper exposure. To compensate for the noise produced in such shooting conditions, the camera applies more aggressive noise reduction which reduces the amount of detail in the image.

• Large aperture of f/2.5. This reduces depth of field and makes objects just slightly closer or further than the point of focus appear blurrier than they would were you able to use a narrower aperture. And the more you magnify an image, the shallower the depth of field will be because you are also magnifying all of that blur.

• Slower shutter speed that could allow motion blur. 1/200 second is fast enough when shooting handheld with a 50mm lens if the image is viewed at 8 x 10 from a distance of 10" by a person with 20/20 vision. When you magnify the image to the equivalent of 30 X 45 you also magnify the blur by the same factor: about 4.5X. So for a field of view yielded by a 75mm lens on a Full Frame sensor, you would need to multiply the 1/focal length rule of thumb by 4.5X as well and use a shutter speed faster than 1/320 second (only if you are also practicing good camera stability techniques). If you are not practicing rock solid camera stability techniques you would need to increase the shutter speed even more.