Nikon D3100 Viewfinder


As with most DSLRs, the Nikon D3100 has an optical viewfinder that lets you view your subject through the lens. Unlike the D3000, the Nikon D3100 also offers Live View mode which allows you to preview the current subject on the LCD monitor.

Nikon's main specifications for the D3100's optical viewfinder are pretty typical for an entry-level DSLR. It employs a less expensive pentamirror design (as opposed to a solid glass pentaprism) with coverage rated at 95% (our test results agree) and magnification of 0.8x (measured with a 50mm f/1.4 lens at infinity, -1.0 m-1). Eyepoint is rather short at 18mm (at -1.0 m-1), and the diopter adjustment range of -1.7 to + 0.5 m-1 is not very generous either.

The Nikon D3100 does however offer more than the usual viewfinder information for its class, however the on-demand grid found in the D3000 and some other Nikons has been dropped. Also dropped are the reference circle for center-weighted metering, and the screen overlays for "no memory card" and the battery indicator (the information display across the bottom retains its battery indicator however).

Nikon has also updated the D3100's viewfinder autofocus point display. In the D3000, the approximate AF point locations were indicated with dense black marks in the viewfinder. For the Nikon D3100, these have been replaced with much fainter markings, illuminated by single red LEDs. The new LED indications are quite bright, but very small, and several of them have a tendency to "bleed" into other points. The worst offender is the center point, which causes the top and bottom points to glow quite noticeably. It's a little distracting, but the glow isn't as bright as a properly illuminated point, so it's still easy enough to tell which points achieved a focus lock.

One feature that owners of older AF lenses will appreciate is the Nikon D3100's exposure meter scale can act as a manual focusing aid, indicating which direction the lens needs to be adjusted to achieve focus. The option for the scale to behave this way is selectable in the Setup menu. This "Rangefinder" function as Nikon calls it, is not available in manual exposure mode as the scale then indicates exposure regardless of the Setup menu setting.

The graphic and table below shows what information is displayed in Nikon D3100's viewfinder.

Focus points
"K" (appears when memory remains for over 1000 frames)
Focus indicator
Flash ready indicator
Autoexposure (AE) lock indicator
Flexible program indicator
Shutter speed
Exposure indicator
Aperture (f-number)
Exposure compensation display
Battery indicator
Electronic rangefinder
Number of exposures remaining
Flash compensation indicator
Number of shots remaining before memory buffer fills
Exposure compensation indicator
White balance recording indicator
Auto ISO sensitivity indicator
Exposure compensation value
Warning indicator
Flash compensation value
ISO sensitivity value


Viewfinder Test Results

Average coverage accuracy from the optical viewfinder. Excellent accuracy from the LCD in Live View mode.

60mm, Optical
60mm, Live View LCD

The Nikon D3100's optical viewfinder showed just over 95 percent coverage accuracy with our reference Nikkor 60mm f/2.8 prime lens. This is about average for an entry-level digital SLR, and slightly exceeds Nikon's specification of 95% for the D3100. The viewfinder image was tilted and shifted somewhat compared to the imaging sensor, which unfortunately is not that uncommon. In Live View mode, the Nikon D3100's LCD showed 100% coverage, though we noticed a very slight vertical shift in the image.


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