You’re shooting film. Assuming you don’t have access to a dark room for film processing, and don’t want to invest time and money in your own scanning equipment, you will have to rely on photo processors to develop and scan your film. Most labs propose the choice between 2 or 3 scan qualities. What should you order?
Our perception of the “minimum acceptable quality” has changed over time:
- In the old pre-smartphone days (12 years ago), the conventional wisdom was that an image was displayed on a monitor at 72 dpi, and that most amateurs seldom printed anything larger than 5 x 7. A 1500 x 2100 scan was good enough.
- we now visualize and share most of our images on high pixel density screens (the “Retina displays” of Apple’s products, but also the 4k or 5k screens of recent monitors and TV sets, for instance) which have 3 to 4 times the pixel density of the displays and monitors we used 10 years ago.
- far fewer of our images are printed (I don’t know anybody who still asks systematically for 4×6 prints) – we only print the best of our pictures, and when we do it, we tend to print LARGE (coffee table books, 11 x 14 posters). A 2400 x 3600 scan constitutes the new normal.
Resolution of the scan of 24×36 film needed for a print or to fill a screen:
In theory, it’s pure math. Photoshop will prepare images for printing at 300 or 600 dots per inch (DPI). If you want to fill a 10×8 page at 300 dpi, you’ll need an image dimension of W=300 x 8 and L= 300 x 10 that is 2400 x 3000.
Photo processors generally offer scans in three levels of resolution:
- low res image: 1200 x 1800 – good for 6×4 prints at 300 dpi at best, a standard laptop screen at 100 ppi, or an iPhone with Retina screen (at 366 points per inch). An image size significantly below 1200 x 1800 will only be good for proofs or vignettes.
- medium resolution image : (2048 x 3072 ) : good for 7 x 10 prints or a Macbook Retina or iPad Pro display at 250 points per inch.
- high resolution image: ( 4492 x 6777): 15 x 22 print or a large 5 k monitor (24in or more).
Let’s compare two images taken in the Atlanta High Museum of Art with the same type of film and the same camera, and scanned at different resolutions:
The lower resolution picture is visibly less detailed (look at the hardwood floor, look at the grain in the shadows). A resolution of 1024 x 1544 is very limited, even for a WordPress blog.
However, the image size alone is not enough to determine the quality of a scanning service.
First, an image with 1200 x 1800 pixels has not always been scanned with a scanner resolution of 1270 Dots per Inch (36mm = 1.42in; 1800 pixels for 1.42 in = 1270 dpi) – it could have been scanned at a lower resolution and enhanced with interpolation.
Secondly, even with the same scanning equipment and the same resolution, images can be massively different, depending on the settings of the scanner and the skill of the operator: as an example, let’s use two pictures taken on the same type of color film and processed and scanned by two different Wolf Camera in-store labs in Atlanta:
The second picture looks much more grainy than the first one, even if the JPG files delivered by the minilab contain the same number of pixels in both cases.
I had noticed the same phenomenon with Costco a few years ago – in the same store, you could get very different results from one day to another one, depending on the experience and skills of the operator on duty that day.
The labs, the services, and the cost
Almost nobody operates in-store minilabs anymore. Pharmacy chains or large retailers that used to process film in-store are now contracting the work to a few centralized labs. They target the amateurs using disposable cameras and 35mm color film.
The enthusiast photographer crowd will be better served by a few large mail to order processing labs such as The Dark Room, The Old School Photo Lab , or North Coast Photo Services (NCPS). They offer a wider range of services and also process color slide and “true” black and white film (such as Kodak’s Tri-X Pan or Ilford’s HP5), in many formats.
I’ve been using The DarkRoom and the Old School Photo Lab a few times. Their prices are roughly in the same ballpark. They develop and scan a 135 film cartridge for $11.00 (the base price includes postage, and The Dark Room provides low resolution scans for free). Medium and High resolution scans are available at extra cost ($4 to $5 extra for 2048 x 3084 scans, $ 9 for 4492 x 6774 scans). The scans are posted on a Web Gallery (no need to wait for a CD to come back through the Postal Service) and can be downloaded to a PC or a Mac as jPEGs (TIFFs are available at extra cost). A free app is also made available to visualize the images on a smartphone.
The differentiator between those services is what happens to the film after it’s been processed:
- Pharmacy chains and big retailers typically DON’T return the processed film to the customer (one can assume it is destroyed after scanning). They generally simply return a CD.
- Services like The Darkroom or Old School Photo Lab return the processed negatives, with or without a CD, but may charge extra fees to cover the shipping cost (The Darkroom) or the cost of the CD itself (Old School).
Other vendors package their offer differently but the prices are roughly in the same ballpark.
A general issue with all those services is the lead time. You seldom get your scans on line in less than 10 calendar days (135 film, negative color film). Speciality items (slide film, black and white, medium format) may take a few days longer. But we don’t have much choice anymore, do we?
As a conclusion, if your pictures are important to you, learn to know your lab
- if they publish a mission statement, read it,
- if they describe their process and how their staff is trained, pay attention.
- and before you send a large order, test them with a single roll of film – you don’t want to discover after it’s too late that they scanned your negatives at the lowest resolution before destroying them.