Digital Zoom

Introduction

The on-camera zoom lens can zoom in and out optically by using the optical formula built into the lens. On the other hand, digital zoom can do the same by magnifying the existing image using software. Nikon Coolpix 990 has a 4x digital zoom in fix steps from 1.2x to 4.0x with an increment of 0.2x. Thus, this digital zoom capability effectively creates an optical/digital zoom of focal length from 138mm for 1.2x to 460mm fro 4.0x. In terms of telephoto power, the 2x digital zoom is equal to the Nikon 2x Tele Converter TC-E2, while the 3.0x extends the focal length to near 345mm and is equivalent to the Nikon 3x Tele Converter TC-E3ED. Digital zoom can be used in both A-REC and M-REC.

Although digital zoom can increase the focal length without the use of a tele converter, there is a price to pay: lower image quality. More precisely, digital zoom means taking the center part of an image and blow it up to the desired resolution using software. The following figure shows the actual relative sizes and area of 1x, 2x, 3x and 4x digital zoom can cover. For a 2x digital zoom, the 2x area is taken out and blow up using software to the size of 1x. This "blow-up" process adds extra pixels; but, it does not add details because the image details are limited by the area of the original image.

The following photos illustrate the effect. The left one is taken with a 2x tele converter (i.e., Nikon TC-E2 Tele Converter), while the right one uses 2x digital zoom.

2x Tele Converter	2x Digital Zoom
Click on the image to see a larger one

The following two images show the center parts of the original images. The image definition of the one taken with digital zoom is poor. By the way, both images are not sharpened; but, sharpening will not help very much.

2x Tele Converter	2x Digital Zoom

The next two images show the upper-left corner of the original images. The sharpness of the tele converter near the upper left is obviously inferior to the center part. But, it is still much better than that of digital zoom.

2x Tele Converter	2x Digital Zoom

Therefore, if image quality is important, digital zoom is not the way to go. A 2x tele converter is a better solution. In these two 800×600 images, the one taken without digital zoom seems to have more details and appears to be sharper.

Operating Procedure

To use digital zoom, you must first use the zoom button T to zoom all the way in (to 115mm). Then, hold the T button for about two seconds. The LCD monitor will show X1.2. Holding button T will change the digital zoom to X1.4, followed by X1.6, followed by X1.8, and so on until X4.0 with an increment of 0.2. This digital zoom ratio is shown next to the zoom scale. See the image below. You can use buttons T and W to select one of these four zoom ratios. Holding button W until no digital zoom ratio is shown on the LCD monitor puts the camera back to optical zoom.

Turning Off Digital Zoom (M-REC Only)

Digital zoom can be turned off in M-REC. To turn off digital zoom, follow the procedure below:

1. In M-REC press the MENU button twice to enter the second M-REC menu. The USER SETTING menu appears (below left). Then, press the down arrow of the multi-selector to highlight ZOOM (below right).

2. Press the right arrow of the multi-selector to select this option. Three options appear (below left). Because we need to turn off digital zoom, press the right arrow to select Digital Tele (below right).

3. Two options are available: On for turning on the digital zoom and Off for turning it off. Use the up or down arrow of the multi-selector to highlight the desired item, and use the right arrow to make a selection.

4. Once the above steps complete, press the MENU button to return to the M-REC shooting mode.

   Note that turning the camera off will not reset this digital zoom option. You need to follow this procedure to turn the digital zoom back on if it was turned off previously..