How to Digitize 35mm Negatives
Intro: 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
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).
- 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:
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
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...
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
This setup is easy to work with and can be useful for other similar projects involving the camera.
STEP 7: The Meccano X-stage
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
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
Everything can be disassembled and stored in a box, when not used.
STEP 10: Try Different Light Sources
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!
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 cropping , rotating 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
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.
Development
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
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
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!
56 Comments
JulioR96 4 years ago
"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."
tholopotami 4 years ago
tholopotami 4 years ago
JulioR96 4 years ago
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.
kurva 8 years ago
Excuse my ignorance, how do you remove the orange mask from the colour negatives?
tholopotami 8 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:
https://www.instructables.com/id/How-to-digitize-slides-and-film-negatives-with-a-D/
KaikenRoldan 8 years ago
Same as Allsop... tanks a lot ;-)
tholopotami 8 years ago
You are welcome. Check the improved version:
https://www.instructables.com/id/How-to-digitize-slides-and-film-negatives-with-a-D/
Allsop 10 years ago
tholopotami 10 years ago
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 11 years ago
tholopotami 11 years ago
rondacosta 11 years ago
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.
ron.dacosta@gmail{.}com
tholopotami 11 years ago
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 11 years ago
FioriOnFire 12 years ago
tholopotami 12 years ago
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 12 years ago
tholopotami 12 years ago
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 12 years ago
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)