Film Jargon: Over/Under Exposure, Pushing/Pulling Film, X-Pro, What?

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If you have ever joined in discussions online (or looked for help) you may have seen people using phrases like “over/under exposing film”, “pushing/pulling film”, “x-pro” or “cross processing” but have no clue what they mean. This article is designed to be an example-led guide for those new to film photography to explain the differences between over and underexposing film, the differences between pushing and pulling film and finally, as a brief look at cross-processing (or X-Pro as it is known).

This is not meant to be an in-depth scientific look at X brand of film, Y brand of camera, or Z brand of chemical/development technique. I have tried to keep it as generic and open as possible. Obviously, your results may vary depending on many factors, such as film stock, whether the film is expired or not, camera, settings, weather condition, metering, but hopefully this article benefits those who have heard these terms before and want a bit more clarity on what they actually mean.


Remember, yOU are in control

When taking a photo, you have full control over how you want that image to look using three tools at your disposal:

  • Aperture
  • Shutter speed
  • Film speed (ISO) and exposure index (EI)

Here’s a quick reference guide from Photoblog Hamburg provided under CC BY-ND:

Credit: Photo Hamburg

Let’s break this down:

Aperture

You can change your lens’ aperture to adjust the depth of field (how blurry or in focus parts of the image are). The smaller the f-stop number, the more light you are letting into the camera, as the lens opening is larger. The larger the f-stop number, the less light you are letting into the camera, as the lens opening is smaller (I know this bit can be confusing when starting out).

Shutter speed

Alternatively, you can change the shutter speed to freeze action, or blur objects and movement. This is measured in seconds, or fractions of a second. The faster the shutter speed, the more the action is “frozen”, with the longer the shutter speed, the more we see movement blurred.

Film speed (ISO) and exposure index (EI)

The speed of the film you use will have an impact on the shutter speed and aperture combinations you can use. A faster film (higher ISO) allows the use of larger apertures and faster shutter speeds but will in turn generally mean larger, more noticeable grain and other differing results.


Although you can’t change the ISO of your film, you can shoot it at a higher effective speed by simply changing the speed you shoot it at – this is called the exposure index, or EI. Allow me to explain…

A lot of film photographers will say things like “I shot and developed this roll of Kodak Tri-X 400 at ISO 1600.” This is technically impossible. The ISO (sensitivity) of a film cannot change. However, we know that the photographer means that they shot Tri-X 400 at an exposure index (EI) of 1600 and developed the film for the same speed — in this case, they underexposed the film in the camera by two stops and compensated by “pushing” the film with two extra stops of development — -2+2=0, no change.

How to set the EI of your film? If you have a camera that allows for manual adjustment of ISO, you simply set the dial to the desired speed. Here’s one way to remember it:

The ISO is the baked-in, unchangeable speed of the film, for example, Kodak Tri-X 400 is an ISO 400 film.

The EI is the Exposure Index, the speed you decided to expose the film at. You can shoot your Kodak Tri-X 400 at EI 50, or even EI 25600 and develop it accordingly. I cover that in much more detail further below.

The dynamic range of photographic film

The photographic film you choose will have a degree of dynamic range (sometimes known as latitude).

Dynamic range is how well a digital sensor (or film, in this case) can deal with ranges of light. If you take a photo and find that some areas are too dark or too light, the dynamic range of the film allows you to correct this in the editing process (a digital or wet darkroom). This allows you to increase the brightness in shadows, or decrease the brightness in the highlights.

Each film stock will have a different degree of dynamic range to it, and this information can usually be found online with a quick search. Generally speaking, slide film (E6) is less forgiving than colour negative (C41) or black and white film stock. So, if you are planning on shooting slide film, you have to be a bit more careful/precise when metering your shot. You can be a bit more relaxed with black and white/colour (C41) negatives as generally, they are more forgiving.


You may have seen a photographer post images from a certain film stock and really enjoyed the look that they have created. You may have then tried that film, looking to produce a similar look yourself, and found that your images look nothing like the ones you have seen online. Assuming that they have not over-edited their photos (which is possible), it could be that the photographer has tried some of the methods below to get their “look”.

Over-Exposing Film

Over-exposing film in camera is when you give the film more exposure (a slower shutter speed/wider aperture than) what the light meter suggests. You let in more light in order to make the image brighter.

This is more common with colour film (negative/slide) than black and white film, but it is still possible with all film. Over-exposing film is useful in situations when there is high contrast, as it decreases the overall contrast in the final image, producing a flatter look to the image. By over-exposing the film, you are also increasing the saturation, as well as reducing the contrast. Many photographers that over-expose their film in-camera will develop the film normally, at the speed/development time it was meant to be (there is no need for anything fancy in development).

Let me break it down with this real-world example.

Film: Kodak ColorPlus (colour negative/C41, ISO 200)
Weather: indoor, well-lit room (no natural light, all LED)
Meter: ISO 200 / f2.8 / 1/60

In order to take the “perfect exposure” my meter suggested that I use f2.8 at 1/60 of a second when shooting ISO 200 film. If I wanted to over expose my film I could do one of the following changes:

Aperture: f2.8 becomes f2 (over exposing by 1-stop)
Aperture: f2.8 becomes f1.4 (over exposing by 2-stops)

OR


Shutter: 1/60 becomes 1/30 (over exposing by 1-stop)
Shutter: 1/60 becomes 1/15 (over exposing by 2-stops)

OR

ISO 200 effectively becomes EI 100 (over exposing by 1-stop)
ISO 200 effectively becomes EI 50 (over exposing by 2-stops)

NOTE: I know this seems strange, but the camera thinks that there is less light than there actually is, which gives us an over-exposed image. If we used ISO 400 (EI 400) instead of 200, it would think that the film is more sensitive to light than it is, which would under-expose the film.

How does this look in the real world?

Below are some examples of just that. In this example, I changed shutter speed, as I was using a tripod and the self-timer on my camera. I wanted to keep the depth of field (aperture) shallow for the image, which left me the shutter speed to change.

To try out the dynamic range of Kodak ColorPlus 200, I shot at 1/60 (“perfect” according to my meter), 1/30, 1/15, 1/8 and 1/4 to show 4 stops of over-exposure. For the sake of balance, I also shot at 1/125, 1/250, 1/500 and 1/1000 to show 4 stops of under-exposure. I was lit from above with daylight/5500k LED lighting and using dual softboxes at a 45 degree angle from either side of the camera.

IMPORTANT: over-exposing images digitally is very different from film. Over-exposing digitally can result in “blown highlights” where all of the detail in the highlights disappears and cannot be recovered. Generally speaking, when over-exposing film you can recover some of the detail in the highlights, assuming you have not shot the film 7-stops over.

In my opinion the film has done an OK job indoors with the lighting. My classroom has no natural light in it, so all lighting is fully artificial. That said, I think that in this example, only the shot that was “perfect” according to the meter as well as +/- 1 stop either side of it is usable in its current form. Of course, if you wanted to edit digitally, you could still use the other shots (with maybe the exception of +/- 4 stops) and recover/fix them to make them usable.


Under-Exposing Film

CHOO CHOO!! It’s the grain train!!

Before I begin this section let me warn you that under-exposing film in camera can result in negatives where you cannot recover your photo if you have exposed it too much. You can lose photos by under-exposing too much. Shooting under-exposed negatives can result in extra grain in your images if you try to brighten the shadows later, so do so with caution, unless you want to buy a one-way ticket on the grain train.

As you may have gathered from the previous section, under-exposing film in the camera is when you give the film less exposure (a faster shutter speed/smaller aperture than) what the light meter suggests. You let in less light in order to make the image darker.

You may want to do this in order to use a faster shutter speed to capture a moving subject, or in low light to stop the shutter speed from being too slow. Many photographers who under-expose a photo for this reason will then “push” the film during development to correct the lack of exposure to light (see the section below).

Let me break it down with this real-world example.

Film: Kodak ColorPlus (colour negative/C41, ISO 200)
Weather: overcast, flat grey sky (typical Britain in the summer)
Meter: ISO 200 / f5.6 / 1/1000

In order to make the “perfect exposure” my meter suggested that I use f5.6 at 1/1000 of a second when shooting ISO 200 film. If I wanted to under-expose my film I could do one of the following changes:

Aperture: f5.6 becomes f8 (under exposing by 1-stop)
Aperture: f5.6 becomes f11 (under exposing by 2-stops)


OR

Shutter: 1/1000 becomes 1/2000 (under exposing by 1-stop)
Shutter: 1/1000 becomes 1/4000 (under exposing by 2-stops)

OR

ISO 200 effectively becomes EI 400 (under exposing by 1-stop)
ISO 200 effectively becomes EI 800 (under exposing by 2-stops)

How does this look in the real world?

Below are some examples. In this case, I had no choice but to change the aperture, as the maximum shutter speed on my camera is 1/1000. So, I took one photo at f5.6 (“perfect”), f8, f11 and f16 to show 3 stops of under-exposure, and the differences in-between. For the sake of balance, I also shot at f4, f2.8 and f1.8 to show 3 stops of over-exposure.

IMPORTANT: under-exposing images digitally is very different from film. Under-exposing digitally you can often recover detail in the shadows and save the image. Generally speaking, when under-exposing film you can recover some of the detail in the shadows, but this comes at the cost of a very grainy image, which may not be to your taste. This also assumes you have not shot the image 7-stops under, in which case, you will have difficulty recovering much detail from the negative.

In my opinion the film handled much better outside when over and underexposed, as I had expected it to. Unlike the previous shots indoors, any of these shots are perfectly usable and I would certainly be happy to post any of them without any editing done to them. Obviously your tastes may vary, but I would be curious to know, which one do you prefer? Let me know down in the comments below.

Pushing Film: Push processing

When you push your film during the developing stage, you are leaving it in the developer longer than the normal time suggested. This time will depend on the film stock and developer you are using, so the times suggested will differ massively. As mentioned in the previous section, pushing film during development is often done to correct an under-exposure that has happened in camera. However, this often results in muddy/grainy shadows in your finished roll of film. You cannot fully bring back what you lost in camera by pushing film in development. So why do it? Pushing film in smaller amounts (1 stop or so) increases the contrast in an image, which works well with certain film stocks, especially black and white.


Using a resource like Massive Dev Chart is useful in this situation as there are often times/combinations for most films/developers that factor in pushing (and pulling) film during development. If you send off your film to a lab like I do, you can ask your lab to push (or pull) your film, but often a lab will charge you extra for this, so consider this when ordering.

I no longer develop my own film due to a lack of time, so below is a hypothetical example to help you with your understanding of pushing film:

Film: ILFORD HP5 PLUS (ISO 400 film)
Shot At: EI 400
Developer: Ilford DD-X
Dilution: 1+4 @ 20c / 68f

If I wanted to develop my roll of film “normally”, the combination above suggests a development time of 9 minutes. If I wanted to “push” my film I would need to leave the film in the developer for 10 minutes to achieve the same effect as shooting at EI 800. This would “under-expose” my film by 1-stop, giving me increased contrast and grain. If I wanted to achieve the same effect as shooting at EI 1600, I would need to leave the film in the developer for 13 minutes using this combination.

IMPORTANT: as mentioned previously, because film is different from digital, where possible it is best to avoid under-exposing or pushing film in development, as it can mean you lose detail in the shadows and negatives can be un-usable in extreme cases. It is not something to fear or be intimidated by. In low-light situations pushing film is fine, you just need to be aware that when doing it, your film will behave differently (side effects, for lack of a better phrase).

If you can live with the increased contrast/grain and general loss of detail in the shadows, then push away. It might be that this the look you are going for, and there’s nothing wrong with that. Most black and white films lend themselves well to being pushed. With colour this can results in colour shifts.

Pulling Film” Pull processing

Pulling film in processing is similar to pushing, but the opposite. Pulling film is usually paired with over-exposed film, and results in less contrast in the final image. Generally speaking, this is not advisable with colour film, as the processing time for colour film is already quite short, and it can result in your negatives looking really flat.

Pulling film during exposure can be done to correct an over-exposed image. Pulling film can be done with colour film, but many photographers only use this when developing black and white film that has been over-exposed. Pulling film in development decreases the contrast, which can help when the photo has been taken in a high contrast situation. Again, using a resource like MassiveDevChart can help with this if you want to check out the times/dilution for your film/developer combination.


Here is another hypothetical example to help you with your understanding of pulling film:

Film: ILFORD HP5 PLUS (ISO 400 film)
Shot At: EI 400
Developer: Ilford DD-X
Dilution: 1+4 @ 20c / 68f

If I wanted to develop my roll of film “normally”, the combination above suggests a development time of 9 minutes. If I wanted to pull the film to achieve the same effect as shooting at EI 200 I would need to leave the film in the developer for 7 minutes. This would “over-expose” my film by 1-stop, giving me decreased contrast and grain.

Olympus OM1N, Kodak ColorPlus 200, ISO 200, other settings vary.

IMPORTANT: pulling film is generally done with black and white film. Yes, you can do it with colour film but this is really uncommon. Colour film tends to look better over-exposed, so this is why it is not done often, as there is little need to correct it during development. Pulling black and white film is more common if you have over-exposed a roll and do not like the look of that filmstock over-exposed and want to recover it back to box speed.

Cross-Processing Film (X-Pro)

Cross Processing is intentionally processing film in the wrong chemicals. This is a very divisive form of development. Either you will love the look or you will hate the look. There will be interesting and unpredictable colour shifts and an increase in the contrast. The best thing about cross processing is unpredictability. You never truly know what you are going to get with it. For some people, this is fun, exciting and part of the creative process.

If this sounds like your kind of thing, to cross-process your film you use the wrong developing process. So, if you had shot colour negatives (C41, Kodak Portra, Fuji Pro400H for example), you would develop it using the chemicals that you would use for colour slide film (E6, Fuji Provia for example). If you had shot colour slide film, you would develop it using colour negative chemicals. Simple.

The most common form of cross-processing involves taking slide film (E6) and developing it using colour negative chemistry (C41). This creates strong colour casts, as well as increased contrast. Cross-processing in this way tends to over expose the film so you may want to under-expose the slide film when taking the photo by 1-stop.

Slightly less common is taking colour negative film (C41) and developing it using slide film chemicals. This results in muted, almost pastel like colours. It can flatten the contrast, so you will need to push the development by a couple of stops to correct this.


Each film has its own look and characteristics, so the colours produced during development can change massively. You can adjust the white balance when editing the photos to compensate for this (for example, a blue colour shift on your image can be corrected by moving the white balance slider towards yellow, or vice versa). This is all down to personal taste, and there is no right or wrong when it comes to cross-processing, just have fun with it!

IMPORTANT: if you get your film developed in a lab, not all labs will cross-process, and some will charge extra for it. Please consider this before you shoot your film. At the same time, slide film is not very forgiving when it comes to exposure, so before you under-expose the film for cross-processing, make sure you have the correct exposure right. It may take a little bit more thinking time, so make sure you are careful with it.

“Under The Bridge” – Lomo LC-A, Cross Processed – @pittaya on Flickr, used under Creative Commons license

Finally

TLDR;

Over exposing film makes the image brighter, and is done in camera. Under exposing film makes the image darker, and is done in camera.

Pushing film during development means a longer development time and increased contrast to increase the ISO of the image.

Pulling film during development means a shorter development time and decreased contrast to decrease the ISO of the image.

XPro (or Cross-Processing) is intentionally processing colour film in the wrong chemicals (for example processing colour negatives in colour slide chemicals or vice versa) to produce colour shifts and increased contrast.

Now that you know all of this, here are some good films to begin experimenting with:


Black and white negative films:

Kodak Tri-X 400 (ISO 400) or ILFORD HP5 PLUS (ISO 400) are both traditional grain black and white films and give you scope to over/underexpose due to their native ISO (also known as “box speed”…literally the speed written on the box.

Modern emulsions such as ILFORD’s Delta series, or Kodak’s T-MAX films aren’t always as successful, so I would avoid them when starting out with over/underexposing or pushing/pulling film.

Colour negative films:

Kodak Portra 400 (ISO 400) or Fuji Pro 400H (ISO 400) are good colour negative films to start with when overexposing. Whilst colour shifts can occur, these two films tend to handle over-exposing better than cheaper emulsions do. You can do it with something like Kodak ColorPlus 200, as I did in this article, but the “side-effects” of over/underexposing or pushing/pulling may be more obvious.

Colour slide films:

Fuji Provia 100F (ISO 100) or Fuji Velvia 100 (ISO 100) are good slide films to cross-process. If you are shooting slide film, make sure you get the exposure right. If you want to cross-process your film, beware the colour shifts, and join the debate on Twitter #SayYoToXpro or #SayNoToXpro, you’ll fall into one camp or the other.

Whether over/under exposing, push/pull/cross processing, your film stock will change the results you get. Whether that film is expired or fresh will change the results you get. What you see one photographer do with a film stock, you may not be able to easily replicate with the same processes (especially cross processing). Remember that it is a learning process. Things will go wrong, and you may not get the results you had in mind, but learn from it and remember to have fun with it all.


Hopefully, this article was useful if you are starting out with film photography and needed some clarification on over/underexposing as well as pushing/pulling/cross-processing film during development. As I mentioned at the beginning, this was not meant to be scientific, or about one particular brand or another. Do you over/underexpose your film? Do you push/pull/cross-process? Share your experiences and tips in the comments below.

~ Tom

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8 thoughts on “Film Jargon: Over/Under Exposure, Pushing/Pulling Film, X-Pro, What?”

  1. Generally a very good article which will help a lot of people. As someone who spent my entire working life developing and printing colour and b/w for pro photographers in central London, I can see some minor flaws, like the comments about Delta and Tmax films not push/pulling well, which is wrong, both types of “tgrain” emulsion push very well, if you use the correct developer, suitable for the “tgrain” films. Cross-processing transparency film is a proven technique that can give consistent results as long as you use the same lab. Each lab that will do the process ( too much xpro film in a c41 Processing machine can throw the whole processing machine off Balance for all the normal negative films) will give slightly different results. Pull-processing colour negative film is a very useful trick for theatre photography or other high-contrast situations, as long as you expose the film for the shadows.

    Reply
    • Thanks for the comment Howard. Yes you’re right, you can push/pull Delta/T-Max without issue, I was coming at this from the perspective of a beginner, who might not know what the correct developer is to use. With time, experience and experimentation with films like HP5, which are more readily available (my local supermarket stocks it), a hobbyist could get good results from Delta/T-Max (a beginner could too, but not all beginners have the access to support/coaching in the early darkroom stages).

      That’s a great tip about using the labs for x-pro. It would certainly be beneficial to try multiple labs if a beginner wanted to try x-pro and wasn’t happy with their initial results.

      Reply
  2. Every time I see a question about this general topic—on FB or IG or wherever—I reference this video by Prof. Agar: https://youtu.be/OdpfRqDDZyw. For those getting started in film, this video provides clear, easy-to-understand explanations about under/overexposure and push/pull processing. The examples provided, from famous (and some not-so-famous) photographers, not only help illustrate the differences between these exposure/processing methods, but also show why one may choose one method over another for artistic reasons. Glad you’re here to promote all these topics, Emulsive!

    Reply
  3. Thank you for putting this together, Tom & EM. This is an excellent summary for various creative options a film shooter has at their disposal. Nice and compact, it’s a good reference for jargon often held dear by mystics of the craft. Good call on using HP5plus, TX400 and ColorPlus200, as examples since they are widely available.

    Reply
  4. “Modern emulsions such as ILFORD’s Delta series, or Kodak’s T-MAX films aren’t always as successful, so I would avoid them when starting out with over/underexposing or pushing/pulling film.”

    This statement is just so patently false that it calls into question the entire article. In fact, Tmax 400 is easily pulled to 100 and pushed beyond 3200 with superb results. I have regularly shot Tmax 400 at 100 and as far as 6400. At high ISO the negatives will be thin and patience is required to get a good print in the darkroom. But to dismiss them in the manner of the author is appalling.

    Reply
    • Thanks for the comment Jason. Whilst yes, you are correct that you can push/pull Delta/T-Max without issue (I’ve done this myself before), I was coming at the article from the perspective of a beginner, suggesting films that are more readily available and/or slightly cheaper per roll (my local supermarket has HP5 and usually some form of Kodak colour film in stock, sometimes stocking Ilford’s XP2 disposable cameras). If I was recommending film photography to one of my students, I was basing it on the kind of things they might find easier to access.

      Based on my own experiences, I found that Tri-X and HP5 were more forgiving when pushed/pulled, giving results that were easier to work with (as you mentioned, the thin negatives at high ISO may be too difficult to work with for someone new to film photography), and have also found that they both work well with a variety of developers. This helps the beginner as they can focus more on the process, than concerning themselves with having the right developer/film combination which can also be confusing when first starting out. Of course, as you get more experienced in pushing/pulling/shooting film in general, you could move on to other combinations (including Delta/T-Max), but for those starting I would always suggest going with what is more widely available and easier to work with before moving into films that require more patience and work.

      Reply

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