Film Scanner Notes:
Each of the film scanners in the table has fans. Prices are list price and discount from www.buy.com and www.bhvideo.com (and prices may change, and may not include controller board and cable). And NewEgg.com has a very good price on the Minolta Dual Scan IV. A higher price does buy more scanner, better optics, infrared dust reduction, better software, and also better dynamic range, giving deeper noise-free detail from dark shadow tones in slides. Dynamic range is quite important for slides, but less important if scanning negatives.
But the dynamic range spec is not shown here, because the advertised number is unfortunately only marketing hype. There are no standards for advertising this value. It is a totally meaningless number as advertised. Don't assume 3.6 is better than 3.4, or that either is achievable. It is not a performance spec, the scanner was not measured. 3.6 for 12 bits or 4.2 for 14 bits is the theoretical maximum, simply the greatest possible value those bits could possibly hold, if all else were theoretically perfect (see page 157). It assumes DMin is zero, DMax is maximum, and noise is zero, all ridiculous. A false 3.6 cannot be compared to a false 3.4. These may be fine scanners, but have other reasons than this number to choose them.
Marketing's scan speed spec is not shown either, because it is also not very meaningful. SCSI is faster than USB 1.1, especially for 20-60 MB scans. Focusing can take a long time. Saving a very large file also takes awhile. Don't be surprised at 3 minutes overall at full resolution and 16 bits. There's lots of reasons, and computer speed is a big factor too. Scanner exposure time is a bigger time factor than interface bus, and this varies with film frame.
Maximum size 24 bit 35 mm film images are about:
| 2400 dpi | 3400x2200 pixels | 7.5 megapixels | 22 MB |
| 2820 dpi | 3800x2600 pixels | 9.9 megapixels | 30 MB |
| 4000 dpi | 5600x3600 pixels | 20 megapixels | 60 MB |
16 bit data will be twice this size in MB. You need at least 4 times that much system memory, and 8 times is better for editing. If that image is too large for the purpose, then try scanning at 1/2 or 1/4 or 1/8 of full optical resolution, using even fractional divisors when possible.
JPG files will be compressed substantially smaller than these uncompressed MB numbers.
Auto Focus is a motorized focusing method, and can compensate for warped or buckled film frames. Other units are fixed focus.
Batch Scanning uses a motorized film feed mechanism to position each film frame. This can allow automatic scanning of multiple images. The table value shown is the number of frames: film strips / mounted slides.
Some few Minolta and Nikon models have optional autofeeders for 50 mounted slides (about $500).
APS film size requires an optional hardware APS adapter (about $120 to $250). These can batch scan the full APS roll. The Canon FS2710 APS adapter is manual and included.
The Multi-Scan feature can scan one frame multiple times (typically 4 or 16 times scanned in one slow pass). Those images are combined into one image, to average out the random scanner noise in the image data. It is an important noise reduction technique to produce clean dark tones from slides (even in scanners with so-called 4.2 dynamic range too). Multi-Scan is not such an advantage for negatives, because negative dark tones are inverted to the highlights where the noise is harder to see. VueScan can multi-scan with some units that don't support multi-scan.
Some scanners provide a fourth infrared hardware channel (RGB+IR) to allow software to detect and remove dust, fingerprints, scratches and other film damage. Such software is Digital ICETM and VueScan. This causes a slight softening of image sharpness, but it is a popular option, and many users consider it essential. Subsequent sharpening can help. IR does not work with conventional B&W films, and often not so well with Kodachrome, but it does work on all other dye-based slides and negatives.
The Nikon units uniquely use LED illumination source instead of a fluorescent lamp.
The Polaroid and Microtek 4000 dpi models are similar hardware, with different software.
Copyright © 2000-2004 by Wayne Fulton - All rights are reserved.
