Film Developing Printing Scanning Explained


unexposed roll

A film is a celluloid base coated with an emulsion of many layers including the most important – the light sensitive Silver Halide Crystals. The more light they’re exposed to, the brighter and less detailed the photograph will be.

When a film camera takes a picture, the camera lens briefly exposes a portion (frame) of the film strip to an image that’s being magnified through the lens.

This exposure burns an imprint into the emulsion and creates what’s called a latent image.

Once captured, that latent image can be developed into a negative, which can be used to create a photograph.

We call film that hasn’t ever been in a camera UNEXPOSED FILM and film that has been in a camera and exposed to light EXPOSED FILM. If you find a roll and don’t know it’s history treat it as exposed.

Colour negative film is exposed to light in a camera in a light tight box. If at any time you open the back and expose that film to light you will have exposed the film to too much light and lose the images. At Snapshot we use a dark bag to investigate issues requiring the opening of the back while film is still inside.


When you bring in an exposed film for processing you'll see or hear these words: DEVELOP, SCAN, RESOLUTION and PRINT so we’ll try to make sense of the terminology. In this guide we are focusing on commercial film processing (not DIY) of negative film (not slide).


Film Developing is the chemical means by which exposed film is treated to transform the latent image into a visible image.

The exposed film goes through developer, stop, then fixer chemistry to create a permanent image on the (now clear)celluloid base that is no longer light sensitive

The developed film is called a NEGATIVE – because colours are inverted (blacks are white, whites are black, reds are green, etc.)


The NEGATIVE  needs to be turned into a PHOTO PRINT to enable sharing, displaying, framing or putting in an album.

In the past this was done by a traditional photo lab

  • Light was shone through the negative and a lens to expose light sensitive paper with an image then the exposed paper went through developer/stop/fixer silver halide chemistry to create a permanent image on the paper (a photograph)
  • This was all done in a light tight system – the paper could not be exposed to any light until the image was fixed

Now this is done by a digital photo lab

  • Processed film is scanned through a commercial roll film scanner to create a digital file.
  • The file is then printed on photo paper - the actual process used depends on the printer system the photo lab has
  • These printing systems are used for printing all digital images - from cameras, photo editors, phones and scans.    

Digital photo printing systems

  • A Wet Lab uses traditional silver halide chemistry but with an RGB Laser to expose the light sensitive paper with the digital image - all done in a light-tight system
  • A Dry Lab  uses an inkjet system with non-light sensitive paper (Snapshot uses a commercial Noritsu Green II minilab)
  • Professional Inkjet roll printers -wide format and desktop

Labs that develop films most likely have a commercial roll film scanner, made by a photo lab manufacturer, to digitise these.

roll film scanner

The higher the resolution required, the slower the process so the higher the price.  A 1200x1800px scan is only suitable for a 6x4” photo, a 2400x3600px scan is suitable for an 8x12” photo, and a higher resolution is required for larger prints.

Once the film has been scanned the lab cuts the long film into shorter strips and sleeves these in archival quality sleeving. Some labs save the scans to CD or USB but most send direct to the customer using a service like WeTransfer.


As per our earlier discussion these are your choices:


Only select if you can scan negatives yourself, or have access to a darkroom, or are just checking the exposure abilities of an old camera.


This is the preferred option for photographers who grew up in the times of Optical Labs. You get a set of processed negatives back along with a set of photos. Before digital the photographer would keep these negatives for such time as they wanted reprints or enlargements in the future.


This tends to be the preferred option for photographers who have grown up in the digital camera era and are used to working with digital images. They may print their favourites at a later stage. The lab we use sends the photographer the files using WeTransfer. You will need to indicate to the lab what quality (resolution) scans you require.


The best of both worlds but the priciest.


By default Photographers who select DEVELOP & PRINT will be given their negatives when they come to collect their prints.

The opposite is happening with the majority of photographers who select DEVELOP & SCAN without the prints. Once they have the digital scans they seem to see no value in collecting their negatives – this is a world wide trend. Photo labs who are sending the scans to the customer via an online system are most at risk of accumulating these uncollected negatives.  All labs are reluctant to throw out negatives but struggling to find a system to manage these and the space to store them.

There are many reasons you should collect and retain your negatives, even if they have been scanned:

  • The negative is the first generation version of the image seen by the eye
  • The scan of the negative may not have been done at a high enough resolution for a larger image you may want to create in the future.
  • Sometimes digital files disappear – a drive failed, the CD becomes unreadable, etc.
  • They're analogue - and that's the reason you captured photos with film instead of digital :)

We have made the decision to dispose of negatives not collected within one year from the date of processing. Throwing away negatives is not something we ever want to promote but if you choose not to collect them we will dipose of them.

We'd love to see you.

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