Experimenting with Exposure Indexing, 17 September 2009


I have occasionally mentioned exposure indexing (or EI values) [1] and push processing [2] in some of my previous photography-themed posts, but for those of you who are unfamiliar with the terms, these are just fancy ways of indicating that I shot and processed the film at a “speed” value other than its ISO rated speed. [3] Thus, while a film may be rated for a speed of ISO 400, when one shoots said film at a different speed than its ISO rated one, one describes the film as having been shot at EI #, where the “#” value corresponds to the speed at which the film was actually shot. Delving into product literature will also reveal that some films are better at being pushed (or pulled) [4] than others. Generally speaking, pushed film will exhibit a greater degree of contrast between light and dark tones, and will also have a far more pronounced grain structure. Sometimes, pushing is required when shooting in low-light conditions, particularly when one does not want to use a flash. [5] Now, why am I blathering on about this topic? The answer, of course, is that the photo I’m including in this post is the result of a shoot wherein I shot an ISO 400 film at EI 1600, and subsequently pushed the film while processing it.


Those of you who are familiar with movies may recognize this location from the film The Untouchables. [6] More recently, the building in the background doubled as the headquarters of Wayne Enterprises in the new Batman series. [7] The building itself houses the Chicago Board of Trade, and outside of cinema, it is well known for its Art Deco design and decoration. I happen to appreciate the building primarily for the latter qualities, though I certainly didn’t mind seeing it feature prominently in the new Batman movies, either. Hey, Chicago’s got some pretty buildings, so the fact that this one can stand up to the competition is probably saying something. For those of you who are unfamiliar with Chicago geography, the street where I was standing is LaSalle Street, and while it continues further south beyond the CBoT building, as you can see, it dead-ends there in downtown. In fact, this is one of the few locations in downtown where the street does not offer an unobstructed view along its length.

Photo Information:

Camera: Canon AE-1 Program
Lens: Canon 50mm f/1.4 FD
Film: Ilford HP5+ ISO 400 (shot at EI 1600) [8]
Exposure: TTL metering

As for why I’d voluntarily shoot this film at EI 1600 during the day (thus, necessitating the use of a rather robust neutral density filter), [9] I was experimenting with the push processing to see if the results could emulate those one would expect to see from older film. I don’t think I quite succeeded in that regard, but it was an interesting shoot, nonetheless. My rationale was that older photographs tend to have the following characteristics: 1) they tend to have pronounced and highly visible film grain, 2) they tend to have a higher contrast ratio than modern film results, and 3) they tend to be a bit less saturated than modern results (perhaps as a result of the higher contrast ratio). The results here have a higher than normal contrast ratio as a result of the push processing, along with highly visible film grain, but I’m not sure it looks old. [10] Hey, one of the drawbacks of being the creative sort is that sometimes, your “creative” ideas don’t actually work out as planned. Still, it does look interesting, so in that regard, I can consider this a success. Of sorts.



[1]: See here for a description of Exposure Indexing (Wikipedia article).

[2]: See here for a description of Push Processing, often referred to simply as “pushing” the film (Wikipedia article).

[3]: ISO = International Organization for Standardization (I’m assuming that the acronym is organized as it is because it is easier to speak “ISO” than it is to speak “IOS” – or that there is already an IOS out there that predates ISO). I’m going to assume that you already know what film speed is. Okay, okay…if you need it, the Wikipedia link to the definition of EI actually links to the article on film speed, so poke around there, if you don’t know what this is. But seriously…you couldn’t be that heavily immersed in the digital realm that you don’t even know what film speed is, could you?

[4]: Pull processing is the opposite of Push processing, wherein a film that has been shot at a speed slower than its ISO rated speed; Push processing is employed when a film has been shot at a speed faster than its ISO rated speed.

[5]: Or, if you’re like me and you don’t know how to use a flash…

[6]: Or so one of my friends swears to me; I’ve only seen this film a handful of times, and while I enjoyed it, I don’t own a copy of it, nor do I well remember it. Perhaps, I should re-watch it, one of these days…

[7]: You know, that Batman series (Batman Begins & The Dark Knight, both directed by Christopher Nolan), not the other one…

[8]: The reason I chose HP5+ is that it performs very well under alternate exposure settings; I have shot HP5+ at EI 800, 1600, and 3200, but only recently shot it at its actual rated speed. Yeah, I know…I’m weird like that.

[9]: Remember that when you push a film, you’re effectively treating it as being more sensitive to light than it otherwise would be. Thus, when shooting in broad daylight, the film would end up being highly overexposed if shot at “normal” settings for that time of day. Cameras that utilize automatic ISO exposure calculation will automatically adjust for this by requiring faster shutter and aperture settings, but since there is an upper limit to these, it may be impossible to use these settings (e.g., if the meter indicates that you need to use a shutter speed of 1/4000 sec. and an aperture of f/22, but if your camera can’t do that, you need to make other adjustments). The solution to this problem is to shoot through a neutral density filter, which artificially darkens the scene (while leaving the color balance unaffected – hence, the “neutral” part of the name), allowing you to use more “normal” settings.

[10]: Oh yeah, I know…the cars tend to ruin that perception, anyways, but you know what I mean.


3 Responses to “Experimenting with Exposure Indexing, 17 September 2009”

  1. renato Says:

    what is the name of this street?

  2. renato Says:

    ooh, the name is there..

    • seeker312 Says:

      Yes, as mentioned in the original post, the name of the street is LaSalle Street; this photo was shot while facing south from approximately Washington or Monroe (I think).

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