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Film Scanning FAQ

• What devices scan film?
• What are the advantages of dedicated film scanner over a flatbed with tranny hood?
• If I buy a 4000 dpi resolution scanner what size prints can I produce from 35mm film?
• If I scan 35mm at 4000 dpi what file sizes (MB) can I expect?
• If I scan 35mm at 7200 dpi what file sizes (MB) can I expect?
• If I buy a 7200 dpi scanner what size prints can I get from a full frame 35mm film?
• I've got an A3 printer. So what is the point of scans at 7200dpi giving A1 prints?
• I have a PC with 64MB Ram. Should I upgrade my memory?
• My printer outputs at 1440dpi, so why is 300ppi printer output quoted?
• What is a USB port and USB2? How do them compare to serial & parallel ports?
• What is meant by scanner bit depth?
• What is meant by Dynamic Range or D-Max? What is the relationship to bit depth?
• What are the options for dust and scratch removal on film?
• Can Digital ICE be used with Black & White or Kodachrome Film?
• How can I scan X-Pan (24 x 65mm) and 6 x 17cm panoramic slides?
• What minimum resolution dpi should I scan at to get various size prints?

What devices scan film?

The majority of people need a reasonable cost film scanning solution giving high quality results so will choose a product from Groups 3 or 4. top

Type	Slidescan & your existing flatbed scanner	flatbed scanner & transparency media adapator	dedicated film scanners
Quality	depends on flatbed 300-4800dpi	medium to high quality 1200 - 4800dpi	highest quality 2700 - 7200dpi

• Get sharper scans through better focusing
  As an example, when it comes to scanning film and slides, the DiMAGE Scan Dual III is superior to a flatbed scanner in many ways. To begin with, it uses advanced optics to precisely adjust the focus point to the surface of the film. A flatbed, on the other hand, focuses on a fixed distance right above the document glass. As a result, scan quality suffers if your film is slightly curved.
  
• Enjoy breathtaking scan resolution 2,820dpi may not seem much better than 2,400dpi, but numbers don't tell the whole story about quality. The DiMAGE Scan Dual III uses its high-precision focusing system and a lens designed exclusively for film to enhance sensor performance. This leads to images that are significantly more refined than the numbers suggest.
• Finish your scans in less time Flatbed scanners cannot illuminate film as brightly as film scanners can. For this reason, it takes longer for a flatbed to capture the amount of information needed to produce a high-quality digital image. The DiMAGE Scan Dual III will thus give you faster scans of either positive or negative film.
• Specially designed film holders ensure that your film is protected around all its edges, and safely secured when inside the scanner. You can load them easily without getting fingerprints on your film.
• Use less space on your desktop Film scanners also take up less space than flatbed scanners, which helps make them easier to place on your desktop. For example, DiMAGE Scan Dual III is 14.5 x 32cm (464cm2) top

If I buy a 4000 dpi resolution scanner what size prints can I produce from 35mm film?

If scan 35mm film at 4000 dpi what file sizes (MB) can I expect?

Answer: 24bit scan = 62.7MB

The Maths! A 24bit scan of 35mm film (1.44" x 0.95" = 36.5 x 24.2mm) scanning at 4000 pixels per inch gives 21.9 megapixels (4000 x 1.44 x 0.95 x 4000 = 21.9 million pixels). 24bits per pixel x 21.9 million pixels = 525 million pixels / 8 bits per byte = 64.177 million bytes = 64,177 kilobytes/1024 bytes/MB = 62.7 megabytes (62.7MB) top

If I scan full frame 35mm film at 7200 dpi with Plustek OpticFilm 7200 what file sizes (MB) can I expect?

Answer: 24-bit scan = 207MB, 48-bit scan = 415MB

The Maths! A 24-bit scan of full frame 35mm film (1.44" x 0.95" = 36.5 x 24.2mm) scanning at 7200 pixels per inch gives 70.9 megapixels (7200 x 1.44 x 0.95 x 7200 = 70.9 million pixels). 24bits per pixel x 70.9 million pixels = 1,701 million bits / 8 bits per byte** = 212.7 million bytes /1000 = 212,700 kilobytes/1024 bytes* = 207.7 megabytes (207.7MB). A 48-bit scan is exactly twice the size of a 24-bit scan (415.4MB)

* 8 bits =1byte **1024 bytes = 1MB top

If I buy a 7200 dpi resolution scanner (Plustek OpticFilm 7200) what size prints can I produce from a full frame 35mm film?

Answer: 34" x 23" (A1 size)

The Maths! 1"=25.4mm. A 35mm film is 36.5 x 24.2mm = 1.44" x 0.95". Assuming that you require 'magazine quality' output then print should be output at 300 pixels per inch. 1.44" length film when scanned at 7200 dpi gives 10368 pixels. 0.95" width film when scanned at 7200 dpi gives 6840 pixels. Output at 300 pixels per inch gives a print of 34.5 " (10368/300) x 22.8" (6840/300) - about A1 size. (A1 = 33" x 23.4") top

I've an A3 size printer. So what is the point of scans at 7200dpi which could give an A1 size print?

Answer: With 7200 dpi scan you can CROP a 35mm slide by 75% and still get an A3 print *

* An A3 print is 16.5" x 11.7". This requires a printer @300 pixels per inch gives 4950 x 3510 pixels. Scanning at 7200 ppi means that 4950 pixels requires a scan of 0.7" (4950/7200) x 0.5" (3510/7200). But a 35mm full frame is 1.44" x 0.95" so you can crop the slide by 75% and still get an A3 size print.

Scanning 35mm at 7200dpi and printing at 300ppi:-

35mm Full frame

Quarter 35 mm

Cropping quarter 35mm film - Prints to A3 size (16.5" x 11.7 ") top

I have a PC with 64MB RAM. What resolution (dpi) 35mm scans will my PC be able to cope with? Should I upgrade my memory?

As a rule of thumb you need three times more Randam Access Memory (RAM) compared to the scanned file size. So 64MB Ram in your PC will cope with a 21MB file size. Larger file sizes will probably make your PC very slow and unresponsive.

Scanning a 35mm slide or negative at 24-bit depth and 2400dpi will give a 23MB file size*. You can print to A4** size.

You should NOT need to upgrade your memory UNLESS:-

• you want bigger than A4 size prints
• you scan at 48-bit depth
• you crop the 35mm film and print to A4

With 23MB file sizes you can print and output at 200 pixels per inch giving preview quality A3*** size prints and still not need to upgrade the PC memory. We recommend Offtek.co.uk to cost desktop memory. As a very rough guide (October 2004) reckon on spending £100-£150 per 500MB (price varies with PC model & memory speed).

*35mm film is 1.44" x 0.95". 2400 x 1.44" x 0.95" x 2400 = 7.88 million pixels. 24-bit depth per pixel x 7.88M pixels = 189 million bits / 8 bits per byte = 23.6 million bytes/1000 = 23,600 kilobytes / 1024 bytes = 23 million bytes = 23MB

** 35mm film is 1.44" x 0.95". 1.44" x 2400 pixels = 3456 pixels. 0.95" x 2400 pixels = 2280 pixels. Printing output 300 pixels per inch gives a 3456/300 x 2280/300 = 11.5" x 7.6" print - approx A4 size print (A4: 11.7" x 8.3")

*** 35mm film is 1.44" x 0.95". 1.44" x 2400 pixels = 3456 pixels. 0.95" x 2400 pixels = 2280 pixels. Printing output 200 pixels per inch gives a 3456/200 x 2280/200 = 17.3 " x 11.4" print - approx A3 size print (A3: 16.5" x 11.7 "). top

My printer outputs at 1440dpi, so why is a figure of 300ppi printer output used?

dpi = dots per inch, ppi = pixels per inch. You need many printer dots to make a pixel. Typically 300ppi from a 1440dpi can give magazine quality prints. top

What is a USB port and USB2? How do they compare to serial and parallel ports?

USB features one "Universal" plug type for all USB peripheral-to-PC connections. USB has largely superceded the slower serial or parallel ports. A USB2 film scanner is backwardly compatible with a PC with USB 1.1. When you transfer scans from the scanner to the PC it will work OK. However if you upgrade your PC to USB2 the transfer will be forty times faster.

Original USB or USB1.1 or USB carries data at the rate of 12 megabits per second (12Mb/s) or 1.5 megabytes per second* (1.5MB/s) - x100 faster than the old serial or parallel port**. So a 150MB scan will transfer from a scanner to PC via USB in (minimum) 100 seconds.

If you upgrade a PC to USB2, by adding a USB2 card into a free PCI slot, scans can be transfered up to 40 times faster. USB2 or Hi-Speed USB transfers data at 480 megabits per second (480Mb/s) or 60 megabytes per second (60MB/s). A 150MB scan transfers to PC in 2.5 seconds.

* 8bits = 1byte
** serial or standard parallel ports (eg. 9pin serial and 21pin parallel ports shown above) transfer data at 115kbits/s (.115Mbits/s) or 0.014MB/s - x100 slower than USB1.1 and x4000 slower than USB2. top

What is meant by scanner bit depth? The number of bits used to represent each pixel in an image, determining its color or tonal range. Bit depth is a term used to describe how each sample in a bitmap describes color. The following are the most commonly used:

• 1-bit: Two colours: black or white
• 2-bit: 4 colors or grey levels
• 8-bit: 256 colors or grey levels
• 24-bit: 16 million colors: 3 8-bit values, one each for red, blue and green
• 48-bit: trillions colours: 3 16-bit values, one each for red, blue and green

48-bit is generally the highest bit depth you would encounter. Photoshop 7 and CS and SilverFast Ai handle 48-bit images. top

What is meant by Dynamic Range or D-Max? What is the relationship with bit depth? Higher Dynamic Range (OD max) can add detail in the shadow tones of prints and slides, and in the highlights of images from negatives. The level of 'noise' is reduced the higher the dynamic range. Flatbed and film scanner dynamic ranges are from 2.0 to 4.8.

Bit depth and dynamic range are NOT the same thing. 36 bit scanners with good dynamic range can sometimes capture more shadow detail from an image than can a 30 bit scanner. Specifically, dynamic range may add more detail in the shadow tones of images from positive film (slides), and in the highlights of images from negative film. More detail at Wayne Fultons Scanning Tips .

D-Max: David Kilpatrick says 'The Flextight probably does 4.0 which is needed for Velvia, the Minolta 5400 claims 4.8 but that is total nonsense - 4.8 is so dense you can't see a lightbulb through it! I think it manages a respectable 3.7 with leeway for contrast and exposure adjustment.'

top

What are the options for dust and scratch removal on film?

Dust and scratch software / hardware can be bought with your film or flatbed scanner to avoid hours of tedious dust spotting. Several options available are:-

• FREE with any film or flatbed scanner bought from DataMind - Polaroid Dust & Scratch Removal software
• Applied Science Fiction Digital ICE (with some Nikon & Minolta scanners)
• FARE (Film Automatic Retouching and Enhancement) with Canon scanners
• SilverFast 6 SRD (Microtek, Plustek OpticFilm 7200 & several other scanners).
• Minolta Auto Dust Brush & Pixel Polish available on Minolta Dimage Scanners
  
  ' Minolta's Auto Dust Brush was somewhat less effective at removing dust than the Digital ICE technology used on the Dimage Scan Elite II /Scan Multi Pro. Also, unlike Digital ICE, it had essentially no effect on emulsion scratches. Overall, the Auto Dust Brush feature is useful, and will save amateurs countless hours of retouching dust specks from their scans, but for professional use it's no match for Digital ICE'.(source: Imaging Resource) top

Can Digital ICE be used with Black & White or Kodachrome Film?

Click here for info from the manufacturers. top

How can I scan X-Pan (24 x 65mm) and 6 x 17cm (617) panoramic film?

Epson Perfection 2450: can scan an area for film upto 5 x 11 inches at 2400 ppi. None of the carriers are designed for 617 format, but you should be able to make your own film holder. Detailed suggestions

Minolta Scan multi pro & Nikon CoolScan 8000ED: scan panoramic film. top

What minimum resolution dpi should I scan at to give various size prints?

dpi	A6 from full frame 35mm	A5 from full frame 35mm	A4 from full frame 35mm	A4 from quarter 35mm	A3 from full frame 35mm	A3 from quarter 35mm	A2 from full frame 35mm	A1 from full frame 35mm
size	5.8"x4.1"	8.3"x5.8"	11.7"x8.3"	11.7"x8.3"	16.5"x11.7"	16.5"x11.7"	23.4"x16.5"	33.1"x23.4"
1200
2400
3200
4000
5400
7200

Film Size: 35mm ins = 1.44" x 0.95" (36.5 x 24.2mm) Assume: 300ppi prints
Maths: (dpi x 1.44 / 300) X (dpi x 0.95" / 300) > size print
Quarter 35mm: see quarter 35mm scanning top

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