Hi, Im trying to figure out what size file I would have if I shot a photo with a D100 in RAW (6.1MP), how many MegaBytes would that file be?
Im trying to convice my husband to go digital and when he can scan a 35mm film image to 45 MegaBytes at a high DPI, well.....I need to know how to convert MegaPixels to Mega Bytes. Can anyone help me? Thanks
Raw files use 1.5 bytes per pixel (12-bit resolution), so 6 MP files come out to 9-10 MB.
It is certainly possible to scan 35mm film at much higher resolution than digital cameras can achieve. Under optimum circumstances, good 35mm film can achieve the equivalent spatial resolution of dozens of megapixels. Of course, there's more to photography than spatial resolution, but if your husband likes scanning slides, why stop him?
Not to take pictures of one's children, particularly when they are small, is a sign of parental indifference --- Susan Sontag
Each raw image is around 9mega bytes. Therefore each megapixel takes around 1.5mega bytes to store. However to convert it into a useable JPEG or TIFF image, the raw data has to be interpolated. The Hi res scans you husband does are not interpolated.
Each high res jpeg saved in fine mode is around 2.5mb and in medium mode is 1.5 mb. Each tiff image is around 19mb.
I looked at the properties of a 6mp D100 JPEG image taken at fine max resoulution setting and it shows uncompressed size of 17megabytes. A slide scanned at similar resolution (3140x2048) showed 18.4mega bytes as its uncompressed size.
...to gauge image resolution. Pixels are a better guide, but not quite the whole story. (See below.) A D100 image taken at full resolution (any format) results in a 3008 x 2000 pixel image or about 6 Mpixels. A 45 Mbyte high-resolution scan of a slide corresponds to a file of approximately 4800 x 3200 pixel dimensions. So a high-resolution scan of a slide has more pixels in it. However, a direct comparison of pixels is not entirely informative: film has a grain structure that is the result of the chemistry used to form the image; digital captures are essentially grainless. So even though there is more inherent resolution in a film scan, it is degraded somewhat by the graininess of the resulting image. Digital images of 6 Mpixels, although nominally of lesser resoultion, actually may appear crisper due to lack of noise (grain.) Mathematically, 6 Mpixel digital has about 3/4 the resolution of 35 mm film, but in reality, there is not much difference to tell for print sizes at least up to A3 size.
For a thoroughly technical discussion of digital camera resolution vs. film see this site.
Absolutely true. In addition, it's not uncommon to have bit of film curvature on a slide or negative. That curvature can throw the focus off during a scan and the edges of a film scan may not be as crisp as those on digital capture.
I have a D100 and also scan slide film (usually Velvia scanned with a Nikon 4000). Both produce excellent quality images, but it would be a mistake to believe that the 112MB scans produced by the Coolscan 4000 are absolutely superior to the D100 images. In some situations, the D100 actually produces better results. The absence of grain really can make a difference in how the images are perceived. In addition, the film curvature problem does show up at times, and in those cases the D100 produces a sharper image.
My own feeling is that you can get quality results from both methods. The decision about which to use should be based on what kind of output you want, how much time you want to spend post-processing, how quick of turnaround time you want, and what kind of investment you want to make. A DSLR can be a great learning tool. The immediate feedback and the ability to shoot a lot of experimental shots at no additional expense can be powerful capabilities.