How to Digitize 35mm Negatives




Introduction: How to Digitize 35mm Negatives

About: I am a physicist working in research, Making things and sharing the experience with others, helps me in many ways.

One of the best ways to preserve old photos is to copy the negatives with a digital camera and then use image processing software to "develop" the photo.

I built a setup for digitiziation with a DSLR to process my old negatives some of which have a sentimental value.

Since I do not have a macro lens, I combined an SLR lens with a couple of cheap adaptors. The rest was improvised from pieces of wood, cardboard , PVC and even meccano parts.

NOTE: Check out a recent update of this instructable!

Step 1: About Film Negatives

Image formation
  • Film photography is based on the sensitivity of  silver halides (AgBr, AgI etc) to light. The upper layer of the film is a coating of gelatin containing crystal grains of silver halides.

  • When the film is exposed to light, some Ag+ ions are excited to higher energy states and a few combine with electrons to form Ag which will act as nucleation centres in the development stage. At this point the latent image is formed .

  • When the film is developed with chemicals,  an oxidation - reduction reaction takes place. The silver ions in the exposed regions are reduced to neutral silver atoms which coagulate to form metal grains. This is a negative image since the film becomes non transparent in the exposed regions.

  • Colour photography is based on a variation of this process with the addition of organic coloured dyes coupled to the silver halides. The film coating  has three layers for the three basic colours (see photo).
Deterioration of negatives
  • Black and white negative images consist of silver grains which are stable over time. The supporting gelatin is sensitive to humidity and temperature but if stored properly B/W film can last for hundreds of years.

  • On the other hand the colour negatives are more sensitive to environmental factors because of the organic dyes they contain. The cyan dyes fade away faster and the negative becomes reddish. Exposure to light causes the magenta dyes to fade also, due to  ultraviolet  light.

Step 2: How Much Detail Is Recorded on Your Negative?

  • The resolution of the image recorded on the negative depends both on the quality of the film and the camera used. Suppose you have been using several cameras of different qualities as I did. We need an estimation of how much detail has been recorded  in each case.

  • The figure of merit here is the resolving power of the camera lens which depends upon the size of the lens and the wavelength of the light source. The resolving power R of a lens of diameter D  is given by the following simplified formula which is based on wave optics:
R (measured in arcsec)=120/D (measured in mm)

A specific example
  • A 58/2 lens  has a focal distance of 58mm and a diameter of 58/2=29mm.  The resolving power is R=120/29=4arcsec. The viewing angle through the camera is about 30 degrees which covers the 36mm  length of the negative. The minimum  sizeof a dot(or line width)  that can be  recorded on the negative is 36mm x 4 arcsec / (30 x 60 x 60 arcsec) =1.3micrometers.

  • Such a camera fully exploits the potential of a  good quality film with a recording capability of about 350 line/spaces per mm.

  • If you repeat this calculation in the case of a low end cheap camera the minimum feature size may become 10 times larger. Such a camera cannot take full advantage  of even a mediocre negative.

Step 3: How Much Resolution Do You Really Need ?

Since the resolving capability of even a normal film usually exceeds your commercial digital camera or scanner the direct answer is :

                                                                     As much as you can get.

Here is a brief justification of the above statement:
  • Standard consumer  films are capable of  recording dense line/space patterns in the range of   50- 150 lines/ mm  ( for example see the  data sheet of  Agfapan 100). Let us workout the lower value.

  • A pattern of 50 lines/mm corresponds to  100 pxls / mm . If you intend to use  a scanner to copy them , you need at least 100 dots *25.2 / inch=2520 dpi.

  • If you intend to use a digital camera , the 36mm x 24mm negative format requires 36*24*100 *100pxls=8.64Mpxls. A 10Mp camera is sufficient.

  • If you repeat the calculations for the upper 150/mm limit the corresponding numbers are 3x2520=7560 dpi and 3x3x8.64=77.8Mpxls !

  • This simply demonstrates the potential  of the film as a  recording medium. It is not a surprise that films are still used for specific applications such as aerophotography.

Step 4: Design of a DSLR Setup

Now, after this lengthy  introduction - which I hope was useful to some people - it's time to get practical.

These are the parts of the setup:

1. Your DSLR.
2. A macro lens capable to frame exactly  the 36x24mm negative. This can be substituted with a common SLR lens and adaptor rings .
3. A film holder that you can make yourself.
4. An opaque plastic screen
5, A light source. I have used two different slide projectors for this as well natural light by aiming on a white wall outside the house. Everything works including a tungsten filament lamp .

Since I needed to have good control of the distance between the film holder and the lens in order to fit the frame exactly, I made a useful x-stage out of meccano parts . You can substitute this with something simpler, but  the stage proved to be useful..

Step 5: I Suppose You Don't Have a Macro...

If you do have one, lucky you, go on and use it.   I used a 2/58 SLR lens.

To mount this on the camera I used an adaptor for M42 (42mm metric threading) for my specific camera and and two M42 extension rings.

I already had these for other applications. I use them to mount other lenses on the  camera as well as to mount the camera on telescopes.

The M42 extension rings come in sets of three sizes and I saw them on e-bay for less than 10$.
I have a pair of such sets that I got from a flee market a long time ago. Never regretted that buy.

Please do not use any other method to mount a lens on your camera (PVC , cardboard ).
Remember that damaging the interior will cost you much more than a set of adaptors.

Step 6: The Optical Bench

I used a 30cm board for the basis of the whole construction and I mounted the camera on a higher platform.
This setup is easy to work with and can be useful  for other similar projects involving the camera.

Step 7: The Meccano X-stage

The purpose of the x-stage is to control exactly the distance between the lens and the negative in order to cover the whole camera sensor width with the image.

No pixels should be wasted!

Of course you can do this by a sliding stage made out of wood, plastic or any other material.

However I needed an excuse to use the meccano of my childhood.

The platform slides between two vertical guides and it is controlled by a 4M screw of 6cm length.

Step 8: The Film Holder

After fooling around with many designs involving springs, plastic, metal etc, , I selected the simplest solution: cardboard .

The film holder is made out of cardboard and it is supported by a thin plywood piece.

A plastic slide part from a slide is the ideal window which must be aligned to the camera lens .

Step 9: The Finished Setup

A cardboard tube completes the setup.

Everything can be disassembled and stored in a box, when not used.

Step 10: Try Different Light Sources

There are two basic methods for illumination

1. Natural sunlight.

You may work outside , set the camera for sun illumination and aim the device towards a white wall.
It works very well for colour negatives.

2. A lamp source

Use a filament lamp combined with an opaque screen, Set the camera for lamp illumination.
I use two different slide projectors I have.

Step 11: Now Shoot!

A few tips for the camera:

1. Exposure time selection.

I prefer to overexpose by a couple of stops. The range of exposure times is from 1/100s to 1/250s

2. Focusing

A DSLR has the very useful feature of magnifying the image x10 times and focusing on a detail.

When doing this I prefer to focus on a regular pattern if there is such on the photo. Otherwise select a region with an edge with a clear separation  line from light to dark.

Step 12: In the Digital Darkroom: Black and White

Black and white is magic.
We have a 3D coloured perception of the world. B/W reduces what we see into pure form and tonal quality .
In photography as well as in painting it is important to balance these elements.
This is what you have to do in the digital darkroom.

Camera settings
The negative was photographed  using  a slide projector as a light source (200W lamp) at 1/250 sec exposure speed.
The projector was 60cm away from the opaque screen.
The camera lens was set at F/8 for less distortion and more depth of focus.

Select a clear pattern for fine focusing.
In this case I selected the chair pattern which was focused by setting the camera in "live view" and  used the feature of magnification x10 times on a detail for focusing. This is a very useful feature of most DSLRs.

Digital develpoment
I used Photoshop 6.0 . The terminology is similar for any other software.

1. The initial shot needs croppingrotating and colour inverting .
2. Then the colour scheme is turned to grayscale This results in  a faint image which needs further balancing of tones.
3. The challenge here is to preserve the  details as well as the gray scale  (e.g.  in the model's hair)  when you try to increase the darks. I strongly prefer to adjust the tone levels instead of using the common brightness/contrast tool.
4. If it is necessary to smooth the tones add some limited blurring (Gaussian Blurr with a range smaller than 3 pixels).
4. Finally you may have to frame the theme by cropping the picture.

About this photo:
I took this shot with a humble SMENA camera back in 1979 using a FP4 Ilford B/W negative which I developed myself. I like the gradation of tones  and the relation of the three people involved here: the photographer/viewer, the painter and the model. One  of my favourite photos over the years.

Step 13: Colour Negatives

This specific negative is 15 years old. The colours have been preserved.

Camera settings

Essentially the procedure is the same as for B/W.
The negative was photographed  using  a slide projector  at  a speed of 1/200 sec.
 The camera was set for  tungsten illumination.


1. The initial shot needed cropping and rotating .
2. Then the colour scheme was inverted.
3. The challenge here is  to balance the colours and tones. I prefer to work by adjusting the tone levels for each colour separately and then make overall adjustments of the whole colour scheme. I avoid using the  brightness/contrast tool.
4. The next step is to control the colour hue/saturation in order to obtain a natural colour scheme. As a rule, the blue colour will need desaturation.

Step 14: Old Colour Negatives Can Be Tough

As discussed  in step 1, when the colour negative gets older, the blue dyes tend to fade away. Therefore the negative becomes reddish and when the colours are inverted,  blue and green tones dominate.

It may prove difficult to restore colour balance. In such cases I work with each colour separately adjusting the range of tones, hue and saturation. I repeat this procedure 1-2 more times.

The photo shown here is from a 30 year old negative. The best I could do after playing around with colours and levels was to trust the "variations " option of Photoshop 6.0. This resulted in a much better balance than that I could obtain manually. Still it does not look natural. Compare the two photos.

Step 15: Conclusions

1. The setup was worth making, it proved to be stable , versatile   and effective . Lighting and focusing are  controlled very well.

2. There was no problem with B/W processing, I processed 34 years old negatives. The contrast was excellent.

3. If a coloured negative is less than 20 years old probably there should be no problem. However treating colours one by one is not trivial.

4. Older negatives may appear as "overpainted " when processed. Probably one could overcome this by treating colours and contrasts in different layers. If it fails you can always turn to B/W.

5. You cannot save everything.  You may have to let go  overexposed,  underexposed or unfocused negatives.

6. This method is faster than  a scanner and it offers much more control of the illumination used and the contrast. It offers the additional possibility to use sunlight (by pointing to a wall outside).

Overall,  judging from the  results obtained so far (more than 200 photos)  I intend to continue using it for the rest of my negatives, as well as for those  supplied by friends!

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    3 years ago

    hi tholopotami , nice tutorial but can you please give more details on this part and what software did you use for that. Will be very appreciated. Thanks.

    "3. The challenge here is to balance the colours and tones. I prefer to work by adjusting the tone levels for each colour separately and then make overall adjustments of the whole colour scheme. I avoid using the brightness/contrast tool.
    4. The next step is to control the colour hue/saturation in order to obtain a natural colour scheme. As a rule, the blue colour will need desaturation."


    Reply 3 years ago

    At the time this was written I used Photoshop 6.0. I currently work using raw data images (my Olympus produces both a normal .jpg and a row image .orf) using Lightroom.


    Reply 3 years ago

    I just read that, good stuff. I just want to do few test with what I have, not too professional like yours. I already did some test, results werent too bad just a little noise in the pictures. What i want if you can provide, is the scheme you used in photoshop so I can be a little more organized. I think I used all the functions you mentioned on this post or the other but randomly and sometimes more that once in the same project, so it might be destructive in the picture. I dont know if you have a shceme in Photoshop (after invert and crop the negative) For example

    1) Adjust saturation in camera raw
    2) Adjust RGB levels separately
    3) Adjust tone
    4) Adjust bright/contrast overall.

    Thats just a random example. Or perhaps you can provide a PSD of the example you used on the woman below Step 13, that looks very nice! I know every picture is different and etc. but having that or if you can mention very detailed the steps - and the order of these. you used there on PS will be very helpful to me. Anyways I previously downloaded the negative you post about that woman to see if i can reach your final picture. I got something good but not as good as yours. Finally if you can also provide few tips on a compact regular digital camera, like using certain value of ISO and using Macro or not. Thank you.


    6 years ago

    Excuse my ignorance, how do you remove the orange mask from the colour negatives?


    Reply 6 years ago

    Dear kurva, the color negative appears
    orange because of the different sensitivity of the film to blue and red.
    Older negatives appear more orange/brown because the blue color dye is
    the first to faint with time. The essential thing is that when the
    colors are inverted the image appears bluish (see step 13 of this
    instructable). It is all about correctly representing the actual colors
    and not losing color information. This can be done in several ways: (a)
    the one I am currently using is to take as a reference a small stripe in
    the frame of the scanned or photographed negative which is also light
    orange and it is supposed to be white in the negative and black (not
    exposed) in the positive photo image. Then I use white balance
    restoration in Photoshop Lightroom . This can be done either before or
    after inverting the colors (b) In Photoshop CS4 and similar suites you
    may use adjustment -> levels and automatic color level adjustment.
    This may not be enough and further manual level enhancement may be
    required. The first method is better because you do not mess with
    separate colors. Check steps 2 and 10 of my other instructable:


    7 years ago

    Same as Allsop... tanks a lot ;-)


    Reply 7 years ago

    You are welcome. Check the improved version:


    9 years ago on Step 15

    I have been looking for something like this for ages, so thanks. Now, I am not at all "handy" so many of these instructables are beyind me—I have managed to make a stand for my iPad out f an eggbox! That is about my level :-) So a couple of questions bearing in mind I will initially be scanning slides and then go on to negatives if I can manage the slides. Firstly what is the purpose of the tube that goes from the camera to the holder? Secondly I have a macro lens and light source, (my iPad with a torch app) so presumaby I could use my tripod to support the camera and just make a holder for the slides. I know this sounds daft but is that right, (I said I was not at all handy)? Cheers, Andrewt


    Reply 9 years ago on Step 15

    Dear Allsop, I think that the use of your iPad a a light source might work.. You may cut a simple mask out of cardboard, put it on the iPad and put the slide on. Shoot with the macro lens. One thing to check is that no patterns from the light source are transferred on the copy. This might come from birefringence patterns or imperfections. If this is so you should keep the screen a distance of 2-3 cms (1" ) from the light source. A tripod on the ground or a small tripod on a table will help you align the camera. You have to manually adjust exposure time.
    Regarding the tube it was meant to avoid stray light. I do not use it anymore, i do the procedure in a dark room.
    I have been using this setup for sometime now and I extended it to slides and 6x6 medium format negatives. An instructable is under preparation!


    10 years ago on Introduction

    this is a good way of doing this, but i have one thing to say. JUST BUY A SCANNER!!!


    Reply 10 years ago on Introduction

    Dear hats9994, I have been using this method for some time now and let me point out why I prefer it, compared to a scanner: When you project the negative you have two important advantages (a) you have absolute control over the white balance of the photo because you can adjust the lighting conditions of the source to the reception of the camera. For example I also adjust the temperature parameter of the lighting in the Olympus. This gives you a much better starting point for post processing with Photoshop, specially for faint color negatives and (b) by using a projector as a source you get the maximum resolution and contrast because of the parallel beam. I have seen real difference in BW negatives processed with a scanner.


    10 years ago on Introduction

    Great Instructable. But I have a problem!!!! I saw your rig details and inmediately assumed you were digitizing 35mm slides wich is what I am looking for. A case of my brain seeing what I do want and need to see.
    After visiting this 'able seven times I just suddenly realized that you are doing negatives.
    Now, can you share/suggest any ideas about digitizing 35mm SLIDES? That will be greatly appreciated as I was about to start building your setup.
    I will be using my daughter's Nikon D7000 with only Nikkor 18:200 lens. Reading your construct I am thinking of using instead my 40 year SLR Canon 50mm 1:1.4 lens with an extender. Any extra suggestions, please.


    Reply 10 years ago on Introduction

    Thanks for your comments! I am glad if this helps you. Of course you can work with slides. The only change is that you do not have to invert the colors with Photoshop. Clip the slide on a cardboard screen. You can use the framed slides as they are. In fact I have used a slide frame on the screen as a guide for the 36mmx24mm format and in order to avoid the "shadows" that would arise from a cardboard window

    You may need to intensify fade out colors.A few suggestions: (a) a real professional work requires the RAW format (b) When correcting the colors with Photoshop use the Levels option and correct the basic colors one by one. (c) Use the Variations option if you cannot decide with the colors (d) I almost always use the Blur option to smooth and connect details (Gaussian blur 1-2 pixels width, no more) and then sharpen the picture. It becomes more clear this way.


    10 years ago on Introduction

    ,,,,, and BTW, I will be using this setup to copy all my Negatives once I am done with the 35mm slides,,,, thanks for this instructable.


    Reply 10 years ago on Introduction

    I think not. The size of the camera sensor (mine is 17mm) is much smaller than the size of the negative (36mm) and you need to form a "light cone" to match these sizes. This is what a lens does. If you just "project " the image on the sensor you will lose a large part of the image.

    However if you just use any lens there will be deformations at the edges of the field. You have a choice between what I describe in this instructable ( a regular lens system + extensions --> a macro lens) and any camera that can be zoomed to the size of the 36mmx24mm negative at a tolerable distance.


    11 years ago on Introduction

    In step seven, you said "I made this as an independent module in order to use it for other projects". Just curious, what other projects did you use it on?


    Reply 11 years ago on Introduction

    Case 1: I found a nice 480mm apochromatic objective lens system and I wanted to test it as a spotting scope. For this I mounted it on the end of a long rectangular board and used the mecano x-stage to focus a telescope eyepiece mounted on the other end. The whole thing was covered by a tube of black canson paper This allowed me to calculate distances for a future construction of the scope.

    Case 2: I have something in mind related to micro-milling . If (and when) I do it I'll probably make an instructable about it. Stay tuned!


    11 years ago on Introduction

    why DSLR

    there are million of compact 10+ megapixel cameras,
    with "close up mode".

    it is possible to set enough light,
    it does not move,
    no complications with DOF

    (i mean DSLR is not soo important)