Introduction: How to Digitize 35mm Negatives

Picture of How to Digitize 35mm Negatives

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

Picture of 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?

Picture of 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 ?

Picture of 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

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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...

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

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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!

Picture of 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

Picture of 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

Picture of 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

Picture of 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

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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!


kurva (author)2016-04-12

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

tholopotami (author)kurva2016-04-13

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:

KaikenRoldan (author)2016-03-06

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

tholopotami (author)KaikenRoldan2016-03-06

You are welcome. Check the improved version:

Allsop (author)2013-07-02

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

tholopotami (author)Allsop2013-07-03

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!

hats9994 (author)2013-01-23

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

tholopotami (author)hats99942013-01-23

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.

rondacosta (author)2012-07-26

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.

tholopotami (author)rondacosta2012-07-27

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.

rondacosta (author)2012-07-26

,,,,, 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.

FioriOnFire (author)2012-04-25

Would this work for a camera without a lens?

tholopotami (author)FioriOnFire2012-04-26

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.

tjok (author)2012-02-01

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?

tholopotami (author)tjok2012-02-02

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!

useraaaaa (author)2011-07-11

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)

DSLR because most point and shoots won't capture the wonderful dynamic range of film!

If you are scanning old negatives it is one thing, but if you really want a decent scan you should be shooting raws on a dslr.

But yeah, like tholopotami says, the idea is that you use what you've got!

Indeed "raws" is the best way to control colours separately. They should be used in the case of coloured films.

tholopotami (author)useraaaaa2011-07-11

The point is that for this task it is better to use the best equipment you have. Before getting the DSLR I did the same job with a compact camera and a similar setup. Of course it can be done.

meddler (author)2011-08-28

Would a Cannon eos xti work?

Kennuf (author)meddler2012-01-24

Not until you look at the front of the camera and learn how to spell "CANON".

tholopotami (author)meddler2011-08-29

I do not see why not. If you want to mount an SLR lens with extension rings as I did the first thing to look for is an M42 adaptor for your model. They do not cost more than 20-25Euros. A set of M42 rings is less than 10 Euros on e-bay. By combining a couple of these rings you can adjust the frame as good as possible.

meddler (author)tholopotami2011-08-29

thank you I will look for that. I appreciate the help.

meddler (author)meddler2011-08-28

Never mind.... I do wonder if I have the ability to build this. It is just what I'm looking for though.

dkennedys8 (author)2011-08-19

Glad to see someone else rocking Olympus DSLRs!

Avatar_I_Am (author)2011-07-26

Nice Instructable.
I also have an Epson V-700, and it does GREAT on [minimum] 6x7 cm negs, and 4"x5" to 8"x10", but I have beed dismally disapointed with 35mm and 6x4.5 negs.

I did, however, find an old film era slide copier that has a t-mount base that will mount onto- and work on- nearly any digital camera, except for the entry level models. They work with negs and mounted slides.

Total cost, about $8.oo [since I already had a t-mount adapter], from the used bin at the local camers store. Most stores don't carry them any longer, but look around. Most camera store employees don't even know what these things are, and they were all over the place just 10~15 years ago!

Using a Nikon D300, I have made exceptional hi-res copies of some WWII negatives I have been looking to print, but couldn't afford to leave with the store- or pay their charges for lower quality scans.

tholopotami (author)Avatar_I_Am2011-07-28

Thanks for noting this. I forgot to mention the option of trying to find a slide copier for SLRs.

hardwarehank (author)2011-07-13

Cool. I'm getting extremely good results on my slides and negatives with my Epson V700 scanner. It costs around $500, though, so this method would be awesome for someone on a budget. Normal flatbed scanners can't do negatives properly.

Ninzerbean (author)hardwarehank2011-07-14

I have a $49 Epson scanner, I use it all the time for black and white negatives, i just reverse the image (blacks turn white, etc) in photoshop after scanning. I'm sure most free photo editing software programs have that option too. My negatives are over 50 years old, it's hard to even see what is on them, so this is pretty magical when they come into view.

hardwarehank (author)Ninzerbean2011-07-15

Yeah, color negatives are really hard to do without a really expensive scanner - I'll bet B&W works fine like you say though. It is really cool to see what comes out - my slides from the 50's look amazing.

tholopotami (author)Ninzerbean2011-07-14

I believe you about the 50 years old negatives. B/W contains only silver microcrystals which will stay there as long as the celluloid can keep them.Only the medium is subject to aging (becomes more yellow because of UV exposure).
Things are different with colour dyes (see step 14)

Thinking about the DSLR setup here is another advantage: When working with B/W I use a projector and an opaque screen. This produces an homogeneous and parallel light beam which helps increase the contrast of the negative image. This may improve the final result compared to a scanner.

tholopotami (author)hardwarehank2011-07-14

Thanks! As you say the problem is that you need more than a normal scanner to do the job decently. The advantage in my case is that I already had all the equipment ad did not have to buy anything. With the DSLR you can experiment a lot . For example you may change the "filament temperature" for lamp exposure from 4000-7000 depending on the light source you are using. This is useful the case of old colour negatives. Even better, with this setup you may use sunlight by pointing to a white wall. It works very well.

sferroni (author)2011-07-14

You can get far better results using the color curves tool, which I did on your second image with GIMP. The result is here attached.

tholopotami (author)sferroni2011-07-15

It looks better than those I posted!

tholopotami (author)sferroni2011-07-14

Thanks for trying this ! In fact I hesitate to use the curve tool since I do not have much eperience with it.

thepaul93 (author)2011-07-15

Is that a Olympus E-420?

tholopotami (author)thepaul932011-07-15

Yes. It is the less expensive of the series and it is also very light. I have an additional 150mm telephoto of the same brand and I modified an older 200mm telephoto for it (see one of my other instructables). I also use it on telescopes.

marcintosh (author)2011-07-14

It is not a surprise that films are still used for specific applications such as aerophotography.

I feel that the move to digital, while good for business and in certain respects the environment and my personal ecomomy (I can now shoot as much as I want last year 5k pix) has been a case of throwing the baby out with the bath water. Negs aren't OS dependent or Harddrive dependent nor do they need power to be viewed. Look to see the prices on medium format cameras on ebay- those guys aren't giving up, neither are the large format shooters..

Thanks for the Resolving Power work with the math - much appreciated.  All in all a very interesting Instructable.
Thanks again,

tholopotami (author)marcintosh2011-07-14

I am glad someone appreciated the calculations!

e5frog (author)2011-07-14

Cleaning the table was perhaps not the thing I thought about as much as setting focus to something in the picture. ;-)

tholopotami (author)e5frog2011-07-14

You are right, what can I say!

e5frog (author)tholopotami2011-07-14

Maybe it was because we wasn't supposed to see the dirt! ;-)
Nice instructable, almost make me want to make my own - but I don't have one of those flashy cameras. Maybe I'll try hooking up a lamp on top of the flat bed scanner instead...

tholopotami (author)e5frog2011-07-14

Before getting the DSLR I used a compact camera of 5Mpxls. I set the camera at 3x zoom and infinity focus and also put a large 4x magnifying lens in front of it. This must be as large as possible to avoid distortions. Then I used the film holder with the x-stage but this time to focus since you cannot focus with the camera.

efra5 (author)2011-07-14

amazing, thanks!

banker (author)2011-07-14

You put a lot of work into this. 100 Quatloos!

tholopotami (author)banker2011-07-14

Thanks! I have been experimenting on the method and trying various setups with different cameras , in my spare time , for about a semester. I really enjoyed the results specially in B/W.

useraaaaa (author)2011-07-11

"gap between the frames" is important/
it can be used in the photoshop to set "white point" and "black point"

tholopotami (author)useraaaaa2011-07-12

Thanks for pointing out this. It is a valid tip. In order not to loose pixels by exposing also the gap I prefer to select this manually by adjusting tone levels even for colour negatives.

nanosec12 (author)2011-07-11

this is an amazing journey that you have invited us to join you on. I enjoy the images you used to demonstrate your process, and I will no doubt be doing something similar to preserve my old negatives. thank you for the great instructable, 5 of 5 from me.

tholopotami (author)nanosec122011-07-11

Thank you for your kind comments. Indeed I enjoyed the journey also!

About This Instructable




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