Slide digitising

  Original picture

Solutions to digitise slides
Two mirrors scanning device
Adaptation of a flatbed scanner
Digitising without digitiser
Solutions comparing

Revision : 03/03/16

Abstract :
Solutions for digitising films and slides. Both Commercial and homemade solutions and a side-by-side comparison of various devices. Double click on images to enlarge.

Résumé :
Diverses solutions pour numériser les films et des diapositives, les solutions commerciales et bricolées, une galerie de comparaison des dispositifs. Les vignettes sont clickables pour agrandir l'image.

Traduire en français 



Everyone has a lot of old 35 mm films and slides. With the explosion of personal computers, it is very desirable to put the best pictures of your collection in a digital format, and engrave (burn) CDs.
There are a lot of solutions to digitise 35 mm and slides, we will compare in next chapters.  

When we speak of resolution, it is always the true optical resolution, and not a commercial resolution, interpolated and without any signification, inflated only for cheating customer.



Solutions to digitise slide and films

Dedicated Film scanner
These high priced scanners works well, but it is difficult to remove dust on films, it is necessary to redo the scan and to repair pictures.

Adapter for camera (in French: photoscope) in macro mode
If you have a good camera, with a short range in macro, it is easy to make an adapter for films and slides. A metallic can is screwed on tripod socket, using a piece of plexiglas as diffuser. Direct sun light is perfect. The problem is to make an exact focus on the film.

Mirrors system for flatbed scanner
I wroten a special chapter on the two mirrors Helwett Packard system, a very cheap and original solution.

Special cover with lamps
A special cover with a window including lamp, a wire connected to the frame, for instance the Epson Perfection 1200 Photo. I have written a special chapter on a homemade solution.

Other systems... 

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Two mirrors scanning device 

This is the strange device, Hewlett Packard Scanjet Classic Slide adapter (details in the links), that works with all flatbed scanners. It's only made by two metallic mirrors, not very well polished. Size of active part of mirrors is 95 * 45 mm. Angle is exactly 85 degrees (Not a right angle!).

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In good position, the slide is ready to be pushed inside. The position seems critical, upper right corner seems to be better.

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The image on "prescan ", without any modification (only big compress).
The quality of mirrors is very important. I tried to copy the original HP system, cutting two glass mirrors of the same size, exploring angles around the original one, it was a complete failure, picture was very dark.

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The good side of films:
Emulsion side is the dull (matt) one, on a slide you have the trademark print, on a film brand name and numbers along the border are backwards (inverted). Always digitise the good side of emulsion…

I got the best result, for a bright image, with a small improvement, putting an horizontal mirror on the system. Picture is better, strange isn't it ?

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Making mirrors

I experimented a lot to make a copy of HP device, only for the fun.
Il tried: aluminium plate, aluminium film (on a flat base), granular aluminium, chrome steel, glass mirror, bright white paper, tin metal, stainless steel… Glass prism is too expensive.
I tried various angles between mirrors. The problem is always the same, light is too low, and interference fringes are a nightmare. HP original system is always better…
It's not the good solution, angles adjustment are too critical for a repetitive construction, forget it.
On this picture you can see HP system, without slide, first one is the perfect position in upper right corner, the lower one is the same but with an error of only one degree of parallelism with moving array. It is not easy to be in the right position to obtain a uniform white area.

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The crazy man's digitiser

It's very easy to make a quick experience, using two commercial silver CDs, with a piece of adhesive tape on the top, on any flatbed scanner. Of course, the round size and the hole is not perfect, but with a good angle adjustment, you can get a very fine picture, but only on the half of the slide, because light is not uniform on a large surface. Quality/Price rate is fantastic!

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Digitising without digitiser

There is of course the legacy method with your 30 years old slide projector, display your image on a screen and take a picture with a digicam (photoscope). With the good angle, picture is fine, but it's not easy to focus on the screen



Adaptation of a flatbed scanner (Epson 1200 U)

A flatbed scanner, with a special cover for film is a good solution. Epson Perfection 1200, with the reference "U " is the usb model, the "P " is the same with transparency cover film adapter. If you have also the very good "U ", model, you can improve it easily, without any modification on the unit.
I found good information at: Byron Sheppar's page (link lost).
The only difference between the Epson Perfection 1200 "U "and "P "model is the special transparency cover with a lamp. When digitising films, the internal lamp is not powered, external one is working. When the cover plug is connected on the scanner (a pin in the plug is grounded), a new window is displayed in the twain driver panel, with two more choices, for positive or negative films. This is the modification, put only a 220 ohm resistor in the plug (or any small value). This resistor can be always connected, you can now shut-off internal lamp by software (selecting film).
The secret of the system is to prepare a piece of black paper with two windows.
Getting the template ready for printing (at 50 dpi)
When starting prescan, the moving array goes first in a stand-by position, under the small window, at 1/3 of the glass, waiting 40 long seconds for calibration, and after scan slowly (only in the small central window).
The system works perfectly, the secret of a good picture is in the homemade light box. Fluorescent bulbs or concentric circular small tubes are good with a white light, tungsten gives bad colours. Small fluo models, as used in sailing ships, with an oscillator at a higher frequency and 12 volts supply, are better than 50 or 60 Hz models.

Detail of rear plug (Information from Byron's page), this small picture is not expendable (2.4 kb).


Upper <1> <2> <3>

Middle <4> <5> <6>

Lower . . <7> <8>

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Resistor is connected between pin 3 (TPU information) and pin 7 (or pin 4, ground).

Pin 8 is the +5 V output supply, pin 6 is a +24 V when TPU is selected.

On this picture of the complete installation, you can see many things!
On the left, 1200dpi optical 35mm film scanner, SCSI, Epson Filmcan 200.
On this unit, HP device, and my two glass mirrors (not working…).
On the bottom a gold Kodak CD Photo in its box.

  Click to expand

On the right, flatbed Epson Perfection 1200 U.
On the glass, the paper template with only one slide in the centre of the area (on this area you can place 4 slides). The position of the calibration windows is very critical. Black side is under.
Above, at 3 cm, a white Plexiglas diffuser plus a piece of tracing paper.
Above a clear Plexiglas, to move back bulb of 2 cm.
The fluorescent bulb (you can find a better solution, but it works)!
Kitchen aluminium paper is the reflector to increase light.

The display of twain panel during prescan.
On the upper choice box, you can select positive film, negative film or opaque.
At 1200 dpi, selecting film, internal lamp is not powered, there is an enhancement of a 4 factor of the picture, size of digitising is 4800*6000 pixels, exactly the size of the windows of paper template of 4*5 inch, 10.16*12.7 cm.

  Click to expand

At 1200 dpi, selecting opaque, internal lamp is powered, digitising is at the size of the full glass 10200*14040 pixels, 8.5 * 11.7 inch, 21*29.7 cm, A4 size paper.

Now, closing the cover, switching from "film " to "opaque ", same black paper template and slide, prescan shows the full glass area.

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Solutions comparing

I made four scans of the same slide with different solutions, resized and compressed, no adjustment (only mirror inverting).

This is a gallery with the same small centre part of a slide resized. The original pictures have deteriorated in quality but relative quality is maintained. Every original images are about 4 MBytes, this image bank, as all other pictures of my pages, is compressed to be smaller than 50 Kbytes!

Original slide:   Original picture   The small gallery:   Click to expand

Image 1: Kodak CD photo, reduced from 3072 * 2048 Pixels, 2000 dpi, size is 18 MBytes. Click on original slide to see this picture, reduced of a 360 factor, from 18 Mb to 50 Kb. Good soft image.

Image 2: HP 2 mirrors device, on Flatbed Epson Perfection 1200 U, 1200 dpi. Good but need a colour adjustment.

Image 3: Epson Filmscan 200, film and slide digitiser, 1200 dpi. Very good.

Image 4: Back lighted Flatbed Epson Perfection 1200 U, with paper template. For this picture, I used only a Philips 15 watts fluorescent bulb economy lamp, at 5 cms of a white plexiglas panel, 3 cms above the glass, 1200 dpi. Good, but can be perfect with a better light box.

Note: A slide is 24 * 36 mm (0.95 * 1.4 inch), in 1200 dpi, gives 1133 * 1700 pixels = 2 MPixels (Fantastic, it's same than 1999 photoscopes!), file is 6 MBytes in 24 bits depth, 10 MBytes in 32 bits. A small compress reduces to one or two MBytes. 




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