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35mm Flim Negative Scanning

Rig and technique for digitizing 35mm film negatives.

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I grew up in the 90's with a mum who was an amateur photographer. My family didn't move to a digital camera until around 2005, so there are a ton of 35mm film negatives lying around that I'd like to digitize.

To scan 2000 frames, local providers would charge $2000 NZD at 2.2MP, or $24,000 NZD at 19MP (!!). Cheap negative/slide scanners I can find in New Zealand top-out around 5MP so they're not really an option. Higher end film scanners like the Plustek OpticFilm are suitable, but they only do film scanning and are a similar price to buying a good macro lens.

After a lot of research I opted to buy a Canon EF 100mm f/2.8L Macro lens and build a mount to scan negatives.

35mm film negative scan
Example scan (cropped) - Two lambs, 1995. Fuji 100 ISO. Click for full-resolution version.
Example scan (cropped) - Olly the cat, 1996. Kodak Gold 200 ISO. Click for a full resolution version (8MB)

Build and process:

35mm Film Bracket.f3d

Fusion 360 model containing both halves of the film gate/clamp and the mount for my light source.

f3d - 606.35 kB - 12/17/2018 at 02:55

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Lower gate.stl

Bottom half of the film gate/clamp

Standard Tesselated Geometry - 201.25 kB - 12/17/2018 at 02:55

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Upper gate.stl

Top half of the film gate/clamp

Standard Tesselated Geometry - 132.31 kB - 12/17/2018 at 02:55

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Bracket.stl

Adapter for the specific down-light I used. You'll probably want to create a custom mount to use for your specific light source.

Standard Tesselated Geometry - 888.66 kB - 12/17/2018 at 02:55

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Light holder.f3d

Fusion 360 model for the down-light case. Unless you're using the same light, this probably isn't useful.

f3d - 85.09 kB - 12/18/2018 at 03:31

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View all 10 files

  • 1 × Digital SLR camera I used a Canon 70D (APS-C size sensor)
  • 1 × Macro Lens (1:1) with minimal distortion
  • 1 × Tripod (or some other camera mounting system)
  • 1 × 3D printed film gate
  • 24 × 10mm x 1mm Neodymium magnets

View all 6 components

  • Professional scan comparison (part II)

    Stephen Holdaway5 days ago 0 comments

    After recieving borderline results from a professional film scan in the last post, I took the same negative to be scanned at Wellington Photo Warehouse, another local store.

    The scan quality this time around was significantly better. The scan was delivered at the same resolution in both JPEG and TIFF (8-bit, but still nice to have), and it cost just $5 - one third of the price per frame compared to the previous store! Here's the result:

    19MP scan from unknown equpment at Photo Warehouse. Click for full-size original (9MB)

    The delivered JPEG file has no EXIF data so I don't know what equipment this was scanned on, but the guy I talked to on the phone before going in said they didn't use a drum scanner or flatbed. He described it as a "transmission scanner" with a light source on one side of the film and a CCD on the other, though that doesn't narrow down the equipment.

    Detail-wise, I'd be happy to scan negatives in bulk at this store if I was going to pay someone to do it. My DSLR scan (left) still appears to have resolved a little more detail, but this professional scan is very close (center). Certainly a lot closer than the previous professional scan (right):

    100% crop of DSLR scan (left), Photo Warehouse scan [unknown equipment] (middle), and the Fuji SP-3000 scan from the previous post (right).

    The crop of both professional scans was about the same at 5% loss of the exposure vertically and horizontally. I don't know what the industry standard crop is for printing 6x4's, but I suspect it's something around this number for practical reasons. I digitally cropped the DSLR scan as close to the edges of the exposure as possible, which is kind of cheating:

    Photo Warehouse scan aligned over DSLR scan - roughly a 95% crop of the full exposure

    It would be nice to have this negative scanned on some other professional equipment to continue comparisons, but with the results I have so far I'm happy that this DSLR + macro lens setup at least matches the resolving power of the equipment I'd otherwise be paying per frame to use.

    Next up I have to sort my colours out.

  • "Professional scan" comparison

    Stephen Holdaway01/11/2019 at 06:36 0 comments

    As a follow-on from the last post, I took the tortoiseshell cat negative to be scanned professionally at a local business. I took it in a week ago and eagerly went to pick it up today - they'd had to send it to their other location to do the super-high resolution scan, so the wait was longer than usual.

    According to the EXIF data, the scan was made with a Fuji SP-3000, which is a fairly well regarded piece of equipment. I held my breath and opened the file, ready to be blown away by a superior scan...and was pretty disappointed:

    "Super-high resolution" 35mm film scan from Wellington Photographic Supplies (WPS)
    19MP scan from a local store. Click for full-size original (6MB) For reference, here's the full-size DSLR scan (10MB)

    I'm not concerned with the different colour - the original image has a strong yellow cast from the sunset, so it was probably corrected automatically or manually with good intent. The problem is that while this image looks alright scaled down, at 100% it's lacking a lot of detail compared to the DSLR scan:

    Fuji SP-3000 (left) lacks detail compared the DSLR scan at a similar resolution (right)

    I initially thought this might be partly caused by JPEG compression as the file provided was only 6MB, but had to save my DSLR scan at 0% JPEG quality to get a similar looking result:

    Left: 100% JPEG quality DSLR scan. Center: same image at 0% JPEG quality. Right: image from store.

    What next?

    I've contacted another local store that I've seen decent scans from in the the last few years when getting film developed. I'll take this same negative in to be scanned tomorrow and see if we can get a better result from them.

    Continued in "Professional scan comparison (part II)".

  • Comparison of DSLR to dedicated film scanners

    Stephen Holdaway12/20/2018 at 07:19 1 comment

    To give an idea of scan quality with a DSLR, here's a comparison against a negative scanned with a consumer-grade film scanner and another scanned with a professional film scanner.

    Basic consumer film scanner

    This Endeavour "Personal Film and Slide Scanner" belongs to a family friend. I'm not sure of its history, but it looks like it was purchased around 2013 for the $149 NZD stickered on the box. This one has a 5MP CMOS sensor, similar to devices that can be picked up online currently for around $60 NZD.

    The negative I chose for this comparison was simply the first I could find that wasn't of people, as I'm in the middle of scanning my girlfriend's family photos. By chance, this roll happened to be an example of exposures not aligning with this scanner's style of mount. The images on the film aren't aligned with the sprocket holes as the mount is designed, so part of the exposure is obscured by the mount:

    Frames not aligned to sprocket holes

    Scanning the left-hand exposure with the Endeavour gave this result:

    Scan from the 5MP Endeavour "Personal Film and Slide Scanner". Click for full resolution.

    The same exposure captured through my DSLR + macro lens setup and processed to a positive manually looks like this:

    Scan from Canon 70D (17.8MP after cropping). Click for full resolution.

    Neither of these get the colour quite right (colour is something I'm still getting the hang of in my processing), but what struck me was how much of the image is cropped out using the consumer-grade scanner. You can see that even if the film was aligned correctly in the mount, a decent chunk of the edges would be lost:

    The original exposure isn't a particularly high fidelity or technically good, but comparing detail between the two scans, I would say the Endeavour is simply not useful outside of quickly emailing an old picture to a friend for laughs:

    Left: 5MP dedicated film scanner. Right: Scan from Canon 70D scaled down to 5MP.

    I've recently seen devices like this with 14MP sensors on AliExpress, but I suspect at this price-point the image quality would still be ultimately limited by the size and quality of the lens inside.

    Professional film scanner

    The mail-in developing service FotoPost we used in the early 2000's used a Noritsu Koki QSS to scan the images sent back on CD, according to EXIF data. The exact model of scanner isn't specified, but the image quality really speaks for itself:

    1.5MP image from a Noritsu Koki QSS in 2002. There's a ton of detail here, despite the low resolution output.

    The same negative scanned by my Canon 70D looks like this when roughly matched for colour and scaled down to the same resolution:

    18.9MP scan scaled down to 1.5MP to match the FotoPost scan. Click for the full resolution version (10MB)

    I've just re-scanned this negative for this post as I found the original scan from a year ago was slightly out of focus while processing it. Even with the correct focus, this DSLR scan seems a tad softer than the FotoPost version. The cat's cheek has more hair detail visible in the FotoPost scan, though at the closest focusing distance I still couldn't resolve this detail, so it may be a result of the image processing or just too small for my lens to resolve:

    Modern professional scanner?

    To continue this comparison post, I'll have this same negative scanned at 18MP by a local service once I'm back from Christmas break. It costs $15 NZD for a single scan at this resolution, but it will give an idea of how much or little I'm missing out on by scanning these myself.

    Continued in: "Professional scan" comparison

  • Scanning 35mm film with a DSLR

    Stephen Holdaway12/19/2018 at 03:23 0 comments

    Here's a quick run-down of how I've been scanning negatives.

    Camera settings

    • Aperture priority mode with no exposure compensation. With my light source, shutter speeds range from 1/100s to 1/1000s depending on the exposure of the frame being captured.
    • Aperture at f8.0 to give good sharpness and provide a small margin of error for getting the focus right.
    • Lens set to manual focus, with image stabilisation turned off.
    • White balance manually set for the light source.
    • Shutter triggering with an infrared remote trigger to avoid touching the camera and adding vibration.

    Framing and alignment

    How much the negative image fills the frame is a balance between resolution and the speed you want to work. I've found the sweet spot for me is framing so the sprocket holes barely enter the frame. This makes it quick and painless to get each frame aligned to capture, and leaves the final crop and any minor straightening for processing later.

    Framing example. After cropping 75px off the top and bottom, and 120px off the left and right , the final image is around 18MP.

    I did experiment with filling the whole frame in-camera, but I found it wasn't worth the extra time and precision needed for a small gain in final image resolution.

    Feeding film

    With my mount, I take the top plate off completely to insert a new section from film the top, then place the top plate back on. To move between frames the top plate is levered up slightly to release pressure, then the film can be slid along:

    It's easy to do this with the remote trigger still in one hand, so it's a pretty quick cycle to capture each frame. Once focus is established for a roll, I use live view to quickly get each exposure framed without looking through the viewfinder again.

    Focusing

    I currently prefer to set focus through the viewfinder by eye, as it's easy to see when peak sharpness is reached across the whole image. Generally I found re-focusing at the start of each new roll was necessary, and more often if the image sharpness looked questionable.

    During the first batch of scanning I did, I used the 5x and 10x zoom function in live view to focus on features or grain, but this frequently resulted in incorrect focus and was more time consuming than looking through the viewfinder.

    Trying to set focus on a frame that is out of focus itself (or has motion blur)  is difficult. I'd recommend setting focus for a roll using a photo that has a fine texture in focus (eg. hair, gravel, grass, carpet). I tried the camera's auto-focus in both in viewfinder and live-preview mode, and neither gave reliable results for me. The focal plane is tiny, so you really need to dial it in manually. Auto-focus would usually focus on marks and dust on the surface of the film rather than on the image in the film's emulsion layer, and it would move slightly with each exposure, even if the focus was already spot-on.

    Ambient light

    I was originally working in a room with the lights off and curtains drawn, but I've found some ambient light has no adverse effects (as long as there's no direct sunlight or overhead lights). It's much more comfortable to work in a room where you can see!

    Organising image files

    To avoid going back to a computer constantly, I note the start and end image number on the camera for each roll as I'm working, along with any available information (date, film stock, descriptions). Eventually when the SD Card is inserted into a computer I run a hacked-together script to use this information to move the images into folders:

    Recording...
    Read more »

  • Light source for scanning film

    Stephen Holdaway12/18/2018 at 03:31 0 comments

    During early testing, I figured out a couple of criteria for the light source:

    • The film has to be mounted away from the light source's diffuser so that any texture in the diffuser is not visible in the final image (ie. very out of focus).
    • The light has be bright enough to obtain a shutter speed of at least 1/100s at when stopped down to the lens's sharpest aperture to prevent any vibration creeping in and blurring the image.

    I browsed local stores and ended up picking this Deta 12W Daylight LED down light from Bunnings as it was bright, had a decent looking diffuser and in testing showed fairly even illumination across the whole surface.

    This apparently has a Color Rendering Index (CRI) of 86, which is fairly decent given the price. I'm unsure exactly how this affects imaging compared to a continuous light source like an incandescent bulb.

    With the dimensions of the light known, I chucked together a friction-fit / clip-on adapter for the bottom plate to screw to that puts 5cm between the film and the diffuser of the light:

    Then a quick case to mount the light facing up:

    All together, this completes the setup with no moving parts:

    The whole setup is heavy enough that the top plate can be lifted off without disturbing the other half, and rubber feet added on the light case stop it sliding around.

    This rig has been fantastic to use for hours on end without causing any frustration. The only thing I'd probably change in a future revision is making the attachment to the light more secure; the friction clip/fit is acceptable, but having screws to keep it exactly in place would help. 

    All CAD files are available to download on the project's main page.

  • Film scanning mount design

    Stephen Holdaway12/18/2018 at 01:33 0 comments

    35mm film tray from a dedicated film scanner. Both cheap and expensive scanners use mounts like this. The Film Toaster and flatbed scanners also use a similar mount.

    I trialed a dedicated negative scanner before starting this project and found that the trays it used were quite fiddly and somewhat fragile. They do make it quick to move between frames, but opening and closing them to change the film was tedious in my experience. Designs like this also assumes frames are properly spaced on the film, which isn't always the case.

    Based on this, I had a few criteria for a custom design:

    • Easy to insert and remove film without catches, latches, etc
    • Easy to align film for scanning
    • Simple mechanism to apply and remove pressure once aligned to keep film flat

    Looking at patents for ideas on how existing high-speed film scanners might handle this, I came across US5400117A: "Film clamp for flattening image frames in a scanning gate":

    A film flattening apparatus and method of operation for flattening a filmstrip image frame against an aperture in a base operable by applying normal compressing force through longitudinally extending clamping elements to compress the longitudinal edges of said filmstrip image frame against said base surface...

    This design has some good ideas, but armed with just a 3d printer, some hand tools and very little experience in mechanical engineering I wasn't sure how I was going to construct something reliable enough with a lever to apply pressure to the film:

    Help..? By this point I'd sketched out a guide and aperture to fit 35mm film, but wasn't sure where or how to apply moving parts.

    After at least a week of mulling over how I was going to make this mechanical contraption work, I found myself fiddling with some small neodymium magnets I'd bought for a different project. It was only then it occurred to me that I could keep the clamp extremely simple just by using magnets to apply force - no levers, hinges or springs required:

    Sketching out where the magnets will fit.

    The existing design was then adjusted to have a top plate that puts the magnets in each half as close together as possible. Screw holes were added to attach the mount to a yet unknown light source, and enough tolerance was given for the film guides to slot into the top plate without catching.

    I printed this in ABS, and it worked even better than I was expecting in practice. The magnets provide enough clamping force to flatten out the film, and additionally make the two halves self-align. As long as the top plate is chucked within 1cm of the right place, it homes itself.

    Printed in ABS with magnets inserted in both halves. I used twelve 10mm x 1mm neodymium magnets in each half.

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Discussions

wim wrote 12/28/2018 at 15:37 point

I have been thinking about this for years, for I have an analog legacy that even outnumbers yours. Bu I never really started it, even got rid of my commercial scanner, for I consider feeding thousands of frames a bigger problem than photographing a single one.

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Martian wrote 12/26/2018 at 19:29 point

Great project.  Beautiful cats too.

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Dave Walker wrote 12/25/2018 at 01:09 point

Hello, have you seen Hamish Gill's Pixl-latr project? https://www.kickstarter.com/projects/hamishgill/pixl-latr-helping-you-digitise-35mm-120-and-4x5-fi

I was one of the Beta testers, and it works really well.

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Dave Walker wrote 12/25/2018 at 01:10 point

Also, the Intrepid team have produced a lightbox with excellent colour rendition, that may be worth looking into:

https://www.kickstarter.com/projects/1436129614/intrepid-4x5-enlarger-print-and-scan-35mm-120-and

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shelly wrote 12/23/2018 at 19:23 point

I have an old Nikon bellows and slide/negative holder, and an old Micro-Nikkor lens (that I tested and it is at least as sharp as their new ones (but no autofocus, which is irrelevant for copying/scanning) and they all work with my D7100 camera. My problem is in converting color negatives - the C41 (Kodak, Fuji) negatives have a yellow layer that was apparently needed for color printing in the ancient times of photographic chemical paper; when I try to invert the scans with photoshop, it creates a bluish cast. Are there any (preferably public domain or freeware) program for reversing negative color images scans?

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Neon22 wrote 12/23/2018 at 19:46 point

I'd suggest the gimp for photo manipulation. and their forum for that specific question.

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Neon22 wrote 12/23/2018 at 04:50 point

IMHO the colour balance problem you're having might be to do with your LED backlight. Its probable it does not have a flat response across the spectrum but instead looks white with the three peaks at r,g,b being balanced. This would lead to the kinds of problems you seem to be having. To test it - capture just the white with an empty slide and examine the channels, or photogrpah a gretag macbeth chart and scan it. The colours wil probably not match. Solution is to buy a more expensive LED bulb which is for photographic purposes. Has more emitters which are under driven and have better flat response.

I've just bought one of these from Bunnings (Silverdale) for my kitchen.

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Greg van Paassen wrote 12/23/2018 at 08:49 point

I second this - google Color Rendering Index (CRI). A Falcon fluorescent  bulb from Photo Warehouse (or other photo studio supplier) could be used with a 4mm thick white acrylic bathroom shelf from Bunnings as the diffuser. (3mm is the minimum for artifact-free diffusion).

To get the best results you'll also need to compensate for flat-field variation in the lens/sensor of your camera - see rawpedia.rawtherapee.com/Flat-Field.

To solve your focus/sharpness problems you'll need two small pieces of picture glass, as used in art galleries, to hold the negatives truly flat and at a consistent distance. (The glass is sometimes called "anti-newton" glass because it minimises internal reflections as well as external ones.)

Pro photo scanners like the Noritsu use, or used, wet drum scanning to get consistent, optically good results (provided the operator was trained). Not something that can be done at home very easily. They also had special sensors that had very high dynamic range (ability to pick up detail in very dark and very light areas). Some of the more expensive modern cameras are getting close, but most aren't quite there yet.

I admire your grit, Stephen, in working through so many photos!

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Stephen Holdaway wrote 12/23/2018 at 12:37 point

I hadn't looked up the CRI for this light, but it apparently has a CRI of 86, which seems respectable given the price. High/utlra-high CRI LEDs would definitely be interesting to test out, along with other light sources.

http://www.ledbenchmark.com/display.php?id=337&name=Deta+12W+Dimmable+LED+Downlight+Kit+Daylight

I was originally looking at glass to flatten the film, but found the magnetic sandwich was good enough™ to get the whole exposure in focus (enough) at f8.0. The main limitation I'm finding with focus is that the focal plane is no more than 0.2mm, and a hand on the focus ring of the lens isn't precise enough to get the focus perfect. A microscope focusing mechanism would probably be necessary to nail the focus with this gear, at which point the glass you mention would definitely be necessary.

Enabling Lens Profile Corrections in Camera RAW has been useful for removing a hint of vignetting added by the capturing setup. The distortion adjustments have been imperceptible, but yeah I have been correcting this.

There's still a lot of scanning I want to do, so all these suggestions are really helpful, thanks. To date I've scanned 1988 through 2004 from my family (`2,800 frames) and 1,300 frames from my partner's family (~49 rolls), but there's still another suitcase full of negatives from my mum's travel/antics, and my partner's mum has a box with 100+ more pouches of photos and negatives.

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Stephen Holdaway wrote 12/23/2018 at 11:34 point

Interesting - I agree this will be a factor in the captured image, though the colour issues I've been mentioning are from me processing these by eye instead of applying actual data about the film, light source, camera sensor etc.

I'll do some more testing around this, thanks!

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Richard Hogben wrote 12/17/2018 at 22:35 point

Nice mount, I've been placing them on a light table up until now. But I like this sandwich holder strategy to keep the film flat. Is there a diffuser on the led light?

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Stephen Holdaway wrote 12/18/2018 at 03:43 point

Thanks! I kind of stumbled into using magnets for this design, but it's worked really well. The top half is easy to remove, gives enough clamping force on the negatives to keep them flat enough, and self-aligns to the bottom half as a bonus.

The light does have a built-in diffuser, and mounting the film about 5cm from its surface keeps any texture from the diffuser way out of focus. I haven't noticed any consistency issues with illumination across the film with this setup which has been nice.

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Mike Szczys wrote 12/17/2018 at 20:31 point

I assume the cat photo is a sample that you converted from film. Fidelity look amazing! How do you feel about the color quality of the captured negatives?

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Stephen Holdaway wrote 12/17/2018 at 20:54 point

Yeah the cat is a full resolution sample (at about 60% jpeg quality for hacakday's 5MB image size limit).

Colour is something I'm still working on - it's quite a manual process to get it right at the moment, and it's done by eye rather than automatically. The negatives are shot in raw, but it's not particularly intuitive to match the original print colours with existing software. Lightroom and Camera RAW for example don't process curves - which I'm using to invert and correct for the film's response in each channel - until halfway through their pipelines, which makes most of the controls have unwanted side-effects.

I'll keep posting updates to this over the next few days; I started this project a year ago and have already scanned hundreds of rolls of film, so there's lots to write about.

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