A few scanning tips


Minolta Dimage Scan Dual II

Note that the new Dual IV is out now.. 16 bit, Hi-Speed USB 2.0, Multiscanning. It should be a hot item for the street price of $300.

The Minolta Dimage Scan Dual II is a 35 mm film scanner, in the low-end price range, under $500 US. It is rather different from the previous Dual model, this new Dual II is 36 bits, 2820 dpi, and USB, and has new software, with Windows and Macintosh versions. The 104 page printed user manual is very detailed (it is also online in the Customer Support section at www.minoltausa.com).

Other features include Auto Focus, Batch scanning, and APS film size with optional APS adapter (about $120). It comes with two 35 mm film holders, for a filmstrip of six frames, and for four mounted slides. Batch scan means it can scan those 4 or 6 images or even 40 APS frames, while you are out of the room.

The Dual II software can run standalone, or as a TWAIN interface to photo programs. As standalone, it offers TIF, JPG, or BMP file formats (or PICT for Mac), and the index number of each frame is appended to the base filename specified.

The software can output 8 or 16 bit data (12 bit data in 16 bit words as usual) or 16 bit linear (uncorrected) data. Full frame 35 mm images are over 3800x2600 pixels at 2820 dpi, nearly 30 MB if 8 bit, and 60 MB if 16 bits. APS full frame gives about 3200x1800 pixels at 2820 dpi, about 16 MB if 8 bit, 32 MB if 16 bit. You would only output 16 bits for subsequent tonal processing in programs that can accept it, like Photoshop, and when that is complete, you would convert to 8 bit mode for storage and use.

The top toolbar has three buttons with big arrows, these are the scan buttons. The first button scans a small index image from all the frames, viewed using the Index Tab (as shown). APS film can have up to 40 frames on the roll.

The second button does a preview scan of the selected frame(s). The dark box shown around the 3rd index image indicates it was selected by clicking it with the mouse. You can select any number of them (with the CTRL or SHIFT key) for batch scans. There is a preference setting to scan the Previews with the Index scan, handy if doing several (about 2 minutes to index six, and over 5 minutes for index and preview for all six 35 mm frames, without focus).

The third arrow button is the final scan button for the selected frames. Each frame can have different scan settings, or there is a Job concept that can be applied to all. The scanner is not speedy, but speed depends on many things, image area, image exposure, computer speed, saving to disk, and focusing (auto focus takes 50 seconds each, but manual focus or VueScan focus is much faster). Plan on 2 or 3 minutes overall for each scan. With focusing and 16 bit, 2820 dpi and full frame, my 400 MHz computer can stretch one image to nearly 5 minutes.

The "Input" resolution is for the final scan, and the "Output" resolution field sets the scaled printing resolution. The scaled output print size is shown if the Units are selected as inches or cm, instead of pixels. A3 and 11x17 inch prints are possible. The 2820 scan resolution shows here that 240 dpi printing resolution will scale the 35 mm image to 11.75 times film size to print on paper at 16.1 x 10.9 inches.

The second toolbar has buttons that vary with the Tabs above it. You can rotate selected frames upright, or mirror flip them, or reverse their order for APS cameras that wind backwards. Also the index scan data can be saved to or restored from an Index file, so the data can be reloaded again later without a rescan (and it includes Preview data too, if so selected).

The Preview Tab shows the selected image and you can make the window any size you want. It allows cropping and focus and Exposure Lock.

The Image Correction Tab has the image contrast and color tools. There is an Auto Correction button there, which can modify the processing with the option choices at right. It often clips heavily and adds considerable sharpening (but less so if one of the keywords is selected). It is disabled in 16 bit mode or if in B&W mode.

The histogram has another Auto Setting button, which is never disabled, and which works like Photoshop's Auto Levels, adjusting the three RGB Points individually, shown below by the three White Point settings. There is much less clipping and sharpening. This is normally my own preference instead of the Auto button.

The Curve tool is fully functional, and it also shows the results of the other settings, very instructional to show how things work. The three white point settings are superimposed with the original dark curve (the light lines, shows well on a color screen). I also lifted the center of the curve slightly higher to increase brightness (gamma). The midpoint of the histogram is Gamma too, shown numerically there. There are even eyedroppers. The Preview image shows the effect of settings too. It's an excellent tool, fully featured, and it works well.

However, do be certain that the image is cropped to be within the actual film frame in the Preview, because any extra dead space around the image drastically affects the auto histogram settings, in any scanner, in every case.

The Color Balance tool has a non-functional curve to show what happens. My dummy settings at right show that the red (upper curve) White Point is clipped heavily, and the green (lower curve) output level is reduced (see Curve Tool).

The Dual II software offers only one generic film type for Color Negatives. It handles this automatically, and often well, but it is a hard job, and some negatives will need adjustment for color cast. This is certainly no surprise, it's a simple fact of life for color negative film. It does provide 16 bit output and Adobe Photoshop LE to help with this, and to be fair, color balance of color negatives is difficult on any scanner. There is another choice too, in that one can always use VueScan for good automatic color balance from negatives, and it is faster too.

Scans of slides are surprisingly good too. Deep shadow slide detail is not breathtaking, never great in any CCD film scanner, but it is far from bad here, and better than expected for this price. The surprise was that there was exceptionally little dark noise, the dark areas were black, but very clean and nice. One really has to hunt for the noise, and noise was not a problem. The Dual II gives very decent scans.

It's a very impressive scanner, especially so if considering the low price.

Copyright © 2000-2004 by Wayne Fulton - All rights are reserved.

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