Can I change my shutter speed multiple times for one film?

Question

I am a beginner to film photography and I just got a new camera (Canon EOS 88). From different questions, I got that the ISO setting needed to be the same for the whole film (meaning that I can't change ISO setting while using the same film). Now, what I don't know is, can I change shutter speed multiple times for one film? Basically I would like to take urban pictures (so car moving or people walking), but I might not use the whole film for that purpose. Therefore, can I change my shutter speed for every picture?

Also, I think I understood that if I lower shutter speed (to get the subject more blurry), it will change the amount of light the camera is receiving? Am I correct?

And last but not least, where can I find an idea of how slow I should set my shutter speed? Because I guess it's a different shutter speed if you want to take a picture of a car or a person walking.

If anyone can help me with that, it would be great. I am kind of lost with all the information I find on internet, and considering how much it costs to develop pictures, I just don't want to make a rookie mistake.

Answer 1

ISO is simply the sensitivity of the film to light. You set your camera to match the ISO of the film so that the light meter in your camera is calibrated to the sensitivity of the film. Thats why you don't change it (we will ignore pushing film and other topics).

From there, you manage the light that hits the film by the combination of aperture and shutter speed. The bigger the aperture (smaller number!) the more light. The slower the shutter speed, the more light.

So yes, indeed you can and should change your shutter speed for each shot on the roll of film. Each shot has its own conditions, and tradeoffs for composition.

Aperture changes will vary essentially how much of the scene is in focus. Think about what you do when you are trying to better see something in the distance: you squint. Same for a camera lens, you want to 'squint' it to see better in the distance. So, in order for stuff in the distance to be in focus, you squint or make the aperture small. Think F/22 for squinting and making distant objects more in focus, vs. f/1.8 which is very wide. So, you vary the light via aperture, but there are pluses and minuses to doing so.

Shutter speed is how long the film is exposed to the light. Longer times, like 1/60th of a second, exposes the film to more light than 1/1000 of a second. Just imagine a high speed camera capturing highspeed action and each frame 'freezing' the action. The more frames, the better the 'freeze'. So, the faster the shutter speed, the more 'freezing' you will get, but the less light. So if you want to freeze action you need high speed and more light.

You simply make trade offs between shutter speed and aperture to balance how you want things to look. Maybe you are ok with more blur in distance to get faster shutter speed in lower light, or you decide distant blur is what you want so you have to manage the slower shutter speed.

Rules of thumb for speed used to be that any shot handheld needed to be at least 1/60th. But, that varied depending on your lens, as longer lenses are harder to hold still enough, so you need to have at least the inverse shutter speed to the focal distance. So a 50mm lens would be handheld at 1/60th just fine, but a 200mm lens would require at least 1/200th. While modern cameras with image stablization have changed the rule of thumb, this still applies to old film cameras.

As for stopping action , it really depends on the action, but you won't find much improvement to blur below 1/200th or so. If you really want it, go for the highest shutter speed the lighting conditions will allow.

Answer 2

Exposure Basics

ISO, shutter speed and aperture (f-stop) are (mainly) about the amount of light that hits the film, and you want to control that amount so that the film receives just that much light that gives you a decent brightness.

Over-exposure (too much light) gives a result where everything is white, whereas an under-exposure results in an all-black image.

• For a specific film roll, ISO tells you how much light this film needs for a good exposure. E.g. ISO 200 means twice the speed of 100, meaning that it needs half the amount of light.
• Shutter speed says how long the shutter is open, letting light reach the film. The longer the time, the more light you get. You typically use fractions of seconds, so 1/30 gives you twice the light compared to 1/60.
• Aperture tells how how big the "window" is that lets light pass through to the film. The naming convention is a bit counter-intuitive, f/4 gives four times as much light as f/8. We aften talk about "full stops", each "stop" meaning half the light, compared to its predecessor. The typical sequence is ... f/1.4, f/2.0, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32 ...

If you do everything manually, you measure how bright the current scene is, and then calculate a combination of shutter speed and aperture that exposes the film to the amount of light that it needs, according to its ISO rating. This can and should be done individually for each photo you take.

There will be multiple valid combinations, e.g. 1/30 with f/11 gives the same amount of light as 1/125 with f/5.6 or 1/250 with f/4. See below for hints on which one to use.

You'll typically use your EOS in an automatic-exposure mode, so the camera does the measurement and calculation for you. This calculation needs to match the film ISO value. E.g. exposing an ISO 25 film with settings that have been calculated assuming ISO 400, will give a vast under-exposure.

Howto

So, always use the ISO setting that matches your film roll. Otherwise, the exposure automatic will automatically produce wrong results.

Within the possible correct-exposure combinations, there are a few image-composition aspects you can consider (over the time, you'll get some experience...), e.g.:

• A shorter exposure time (with aperture wider open to get the same amount of light) "freezes" motion (e.g. good for sports), while a longer one gives you the risk of motion blur, either because of a moving object or by a non-steady camera.

• A wide-open aperture (smaller f/ number, with a shorter shutter time) gives a shallow depth of field, meaning that objects closer or further away than the focussed one get blurry. Sometimes you want this, so the object better stands out from the background, sometimes not.

If you also have a digital camera (with ISO, aperture and shutter controls accessible to you), you can use it for experiments - you'll immediately see the results of various combinations, at zero cost.

Answer 3

There are many ways to explain how the “exposure” is controlled. We are taking about adjustments that impact the amount of light energy the film or digital sensor receives when you take a picture. I like to think about exposure this way --- invention a drinking glass with a line of demarcation drawn midway up. Your task is to fill the glass at the sink to the line. Overfill or underfill = inaccurate exposure.

The factors are a. size of glass = ISO b. time under the spigot = shutter speed c. water pressure = scene brightness d. aperture diameter = f-number. All these four factors intertwin to make up exposure = amount of desired light energy playing on surface of film or sensor.

You are free to change any of these four factors to your heart’s desire. If the media is film, you purchase a film type with the ISO required. We generally set this value only once before we shoot. If digital, we are free to adjust on an as need basis. Shutter speed used is changeable for each different picture opportunity. Scene brightness can be altered by time-of-day, bringing to bear artificial lighting or reflectors or location. Iris (f-number) adjustment adjustable each picture based on your preference paired with scene brightness. Bottom line – no shutter speed or f-number restrictions, there are no rules regarding these adjustments we are talking creativeness.