It has a 16 megapixel sensor. In short, the sizes here are not unusual considering the amount of information being gathered. If the image is instead saved in the 8-bit per channel mode, that value will be cut in half to about 46 megabytes. In other words, any file size for the RAW capture file that is less than the bit uncompressed value for the image based on pixel dimensions is not too surprising.
In the specific example cited here, the information related to the NEF file size suggests that the captures are being processed at a lower bit depth, are being captured at a lower resolution, or have compression applied all of these options are available for the Nikon D4. Every digital photo is composed of pixels--millions of them. Pixels are an easy thing to measure, so many people buy a camera that captures a lot of them, assuming that more pixels equals better quality.
As any camera advertisement will reveal, cameras are typically rated by the megapixel, which describes how many millions of pixels are embodied in a photo. A 1-megapixel camera takes photos with a million pixels in them; a megapixel camera captures 20 million pixel photos.
Think of it like a grid that tells you how wide and tall the photo is. Consider the Nikon D, a megapixel camera. It takes photos that are by pixels. Multiply those two numbers, and you get about 16 million. Compare that to the Apple iPhone 4s, which takes photos that are by pixels: times is about 8 million, or 8 megapixels.
Here I've stacked a photo from the iPhone 4s on top of a photo from a Nikon D so you can see how the resolutions compare. The number of megapixels gives us an indication of the resolution of the photo. Imagine zooming in to a photo until you can see every pixel on the screen, like the image below.
The resolution tells you how large your monitor would have to be in order to see the entire photo. So what do megapixels buy you? In a word, detail. More pixels can capture more fine detail so you can crop away unwanted parts of the photo and still make a high-quality print.
Consider this: If you crop away half of a megapixel photo, you'll still end up with a 6-megapixel image, which should have a lot of rich detail. In general, if you're comparing two cameras with similar megapixel counts, the one with the larger sensor will generally take better photos.
That's why some photographers pay a premium for digital SLRs with full-frame sensors. While the megapixel rating tells you how many pixels are in a photo, there is another important thing you sometimes need to know about your photo: the file size of an image that the camera produces. This directly affects how much storage space it takes up on your hard drive, its size as a file attachment in email, and how long it takes to traverse the Internet.
You might think of this as how "heavy" the file is, as if you were weighing photos on a scale. Alas, there's no direct way to correlate pixel size and file size. A megapixel photo might "weigh" less than a megabyte on your hard drive. Or it might "weigh" as much as 6 megabytes. The file size depends on several factors, including the number of megapixels, the file format you're using such as JPEG or RAW , and the amount of file compression used to save the photo, which is sometimes referred to as the quality setting.
You can use a lower quality setting when saving a JPEG to significantly reduce the file size. Of course, if you try this, always save the smaller photo as a new file, so you don't damage your high-quality original.
0コメント