A Guide to Film Specifications and What They Mean

When you’re just starting out shooting film, it can be a little overwhelming understanding all of the technical information about your film, and knowing what to purchase. This guide will take you through the various properties of a roll of film, what they mean and how they will affect your shooting and developing process.

What are the different types of 35mm film

What are the different formats?

The first place to start with buying film is knowing your format. This categorises the size and shape of the film - 35mm (135) is the most common (and the format of all of Max’s cameras) then 120 (medium format) and finally 4x5 (large format). 

There are then ‘obsolete’ films that are no longer made, or films like 110 which are super rare - but you don’t really need to know about those yet! 120 film is always 6cm wide, vs 35 being 36mm wide, for a sense of the size difference.

Size of 35mm film

As 35mm film is the most popular, it has the broadest range of emulsions (varieties of film essentially). It also has the most economical number of images, sold as either 24 or 36 exposures (individual shots) per roll. If your film camera is described as 35mm film camera, it will use this format of film.

Comparatively, 120 films will have 12 exposures, despite their costs per rolls being in the same region. Often, there will be the same emulsions available on 120 and 35 formats - you can expect the same aesthetic, but medium format, as the negative is so much bigger, will provide more detail.

Different types of film format, medium format and 35mm film

How do different types of film differ?

Now you've understood which format of film you are looking for, there are some technical details that will determine the results you get with different rolls of film. Don't worry, we've explained it all as simply as we can below.

What is the ISO (ASA) of film?

The next fixed property of film we need to think about is the speed, which is also known as the ISO, or more rarely ASA. When we say ‘box speed’, it simply means the advertised speed of the film. 

This is a measure of the light sensitivity of the film - less sensitive film will be denoted by a lower number, and requires more light to expose to the same level as a faster film. This would result in different aperture or shutter speed settings being required when you’re shooting, to allow more light in. 

ISO diagram for 35mm film

Your film ISO will form one apex of your exposure triangle, and will be fixed for a roll of film while you vary the other two properties.

Exposure triangle for 35mm film cameras

If you shoot 35mm film with automatic settings or with a point and shoot, it is worth checking if your film is DX-coded. This is a marker on many film canisters which allow the camera to tell the film speed, and number of exposures on a roll. If your camera does not enable you to manually set your ISO, you will need a 35mm film that is DX-coded (which is more often than not), or a DX code sticker which you can put in the location a marker would be.

Example of DX coding on 35mm film canister

What is a low-speed film?

Films in the range of 20-200 ISO are classed as low-speed, meaning they are less sensitive to light. This means you need to be shooting it in well lit conditions. Otherwise you will likely need a long shutter speed and, without a tripod, may get shake in your final image. Low speed films provide a finer grain. The lower the speed, the finer the grain, and so these films are great for capturing fine detail. It’s lovely on bright days.

Examples of low-speed films include Kodak ProImage 100, Kodak Ektar 100, Ilford FP4 Plus (125), and Kodak Gold 200. 

Example of Pro Image Kodak film - what is 35mm film
Examples of ProImage 100
Example of Pro Image Kodak film - what is 35mm film

What is a high-speed film?

These range from 400 all the way up to 3200 ISO, and are much better on overcast days or in low light. They are also great if you want to shoot a fast-moving object, as a higher speed film will be able to tolerate a quicker shutter speed (when less light would be allowed through). As the speed increases, the grain becomes more noticeable.

Examples of high-speed film include Kodak Portra 400, Kodak Ultramax, and Cinestill 800T.

Example of Kodak Ultramax film - 35mm film camera shop
Examples of Kodak Ultramax
Example of Kodak Ultramax film - 35mm film camera shop
Examples of Cinestill 800T 35mm film - 35mm film camera shop
Examples of Cinestill 800T
Examples of Cinestill 800T 35mm film - 35mm film camera shop

Should I use colour film or black and white film?

You’ll also need to choose whether you want to shoot in black and white, or colour. There has been a shortage of C41, the chemical used in colour film for several years now, and so black and white film is often easier to get hold of than C41. 

That said, the turnaround times for labs to develop black and white are often longer, as they are often only processed on a weekly basis. 

The chemical processes used for C41 vs black and white are different, so you will need to specify when paying and sending off your film. 

There are notable anomalies though - Ilford XP2 for example, is a film that appears to be black and white, but is not a ‘true’ black and white, as it has C41 composition and is developed as if it is colour film.

What are the differences in colour films?

The key comparison between colour films are their saturation. This is a measure of how vivid/intense the colouring is and the palette that results for a given film. 

Kodak films are known for having warmer tones than say, Fuji, which has a cooler profile.  This can result in two 200 ISO films for example, looking very different. 

Films at the lower price point, like Colorplus, often have more washed out tones. Pricer films like Ektar on the other hand, have high saturation and are very vibrant. 

Films may also have bias towards individual colours or tones; the varieties of Kodak Portra are professional grade film and are optimised for skin tones.

Examples of Fuji C200 film for 35mm film cameras - 35mm film camera shop
Examples of Fuji C200
Examples of Fuji C200 film for 35mm film cameras - 35mm film camera shop

What are the differences with black and white film?

For black and white film, contrast is key. This is the degree of difference between the darkest and lightest parts of the image - the smaller this difference, the lower the contrast and the higher level of detail in the shot.

Kentmere Pan 400, for example, has less contrast than Ilford HP5. 

Examples of Ilford XP2 35mm film  for 35mm film cameras
Examples of Ilford XP2 
Examples of Ilford XP2 35mm film  for 35mm film cameras

What is remjet and ECN-2?

That C41 shortage we mentioned earlier? There have been significant shortages of colour film, with manufacturers struggling to keep up with demand and prices rocketing in turn. While Kodak have been producing film for stills like Ultramax and Gold, they have also been producing motion picture film for decades, known as Kodak ECN-2 film.

The key difference between ECN-2 and C41 is that ECN-2 is coated with a black carbon layer called ‘remjet’. In its intended use, remjet forms a protective layer which defends against the scratches and static that film is likely to incur when it is passing through the camera in the much faster speeds associated with motion picture filming, rather than the slower speeds used when taking stills. 

What is remjet and why is it different to C41

In a traditional still camera, it will work just the same technically. The key aesthetic difference is that the darkness of the carbon layer will limit refraction of light and can produce halos on highlights. When buying a film based on Kodak Vision, it will often have an assigned ‘D’ or ‘T’ after its ISO value. ‘T’ indicates that the film is tungsten balanced. If you’ve ever taken a photo indoors and noticed the yellow-y hue that artificial lights can take on, tungsten film will counter this and produce colours that appear more accurate to human perception of colour and lighting. ‘D’ indicates that film is daylight balanced, which is something of the standard setting for film.

The developing process is very different though. When processed by normal C41 processes, ECN-2 film will alter the chemistry of the developing bath and pollute with the gooey lifted remjet coating. This can mess up a labs scanners, damage other people's negatives and cause a huge knock on effect. It is important to know what you are shooting, and if you are going to shoot 35mm film with the remjet backing still present, that you send it to a lab that can accommodate, and you will likely need to pay a premium. 

Examples of ThisIs HowIRoll ECN-2 film
Examples of ECN-2 film
Examples of ThisIs HowIRoll ECN-2 film

The other option is to buy a film that is based on the Vision motion picture film, but has a prewash carried out on it. This means the remjet layer has been removed PRIOR to you shooting, and you can process as you normally would for C41.

What is experimental film?

Finally, the market also has a great deal of experimental films. These may have a colour tint, alter the appearance of particular colors, or add special effects over the top of the image. Some brands choose to double-expose the film with colours or lights to give the effect of light leaks or deliberate patterns, such as hearts. Brands like Lomography, Dubblefilm, Revolog, Kono and BKIFI produce lots of these.

What is expired film?

All film has an expiration date, by which the chemicals may start to degrade. We have another blog post all about expired film, which you can read here.


  • Make sure you know which format film your camera uses. Most are 35mm. 
  • ISO relates to how sensitive the film is to light. The higher the number = the more sensitive. 
  • Low speed films range from 20-200 ISO. 
  • High speed film range from 400 to 3200 ISO. 
  • Film is available in black and white, or colour.
  • Colour film is generally developed in C41 chemicals. 
  • ECN-2 film is motion picture film with a layer removed. 
  • Experimental film is film that has been altered. 
  • Expired film can be used in all cameras and has slightly different rules for exposure. (Read here.)

Article written by: Daisy

Daisy is an artist, turned analogue photographer. She works as an engineer and she enjoys photographing her travels and adventures. She posts her work on her Instagram: @whisquila.shots

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