From Taking Pictures to Photography (01): Basic Parameters of the Camera

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From the Start to the End of Photography

My first card camera, a Nikon COOLPIX S200, was a possession I acquired during my middle school days.

Many people suggest to photography beginners that equipment is not important and you shouldn't expect to become a photographer overnight; just keep taking photos and you will naturally get better. I once believed in this advice.

So, in those days when the internet was not yet a ready repository of knowledge, I took my camera everywhere to shoot, trying out various things. I indeed wholeheartedly embraced the notion of shooting a lot, but what followed was not growth but greater confusion.

I didn't have many people around me who knew about photography, I didn’t know what a beautiful photo was, and all I did was repeatedly compose odd and skewed frames. There weren’t many around me who knew about cameras either, so my understanding of film cameras was limited to knowing that film would be ruined if exposed to sunlight, and I always thought that the colorful noise when shooting night scenes with a digital camera was my own fault. I didn't know what a tripod was or understand concepts such as aperture, shutter speed, or ISO. After trying various modes on the camera, I just switched back to automatic.

Thus, after accompanying me throughout my entire middle school, as the quality of smartphone photos gradually caught up, I stored away the camera in my home during college. My experimentation with "photography" started with "taking photos" and also ended with just "taking photos."

Years later, when I started working, I bought myself a mirrorless camera, the celebrated Sony α6000. By then, the internet was filled with a mix of good and bad information, and by exploration, I chose my first affordable prime lens and tried to shoot using aperture priority mode. Nevertheless, I still had many puzzling questions, such as why I would need a small aperture when I have a large one and what are the drawbacks of a zoom lens besides being expensive.

Falling into the same predicament as before, naturally, led to the same results. After a while, this camera too was packed away in a box, and just a few years ago, the kit lens was no longer focusing due to the aging of its internal plastic components.

It wasn't until a couple of years ago that I finally came across an article by Sean Ning titled "Photography Notes: Photography Isn't That Hard to Learn". Regrettably, I searched for a long time but couldn't find any information about the author. There's a website that I suspect belongs to the author, but without concrete evidence, I won't share it here.

The article was clearly written around 2010 and was obviously a PDF exported from Word, feeling very much of its era. Despite its age, the content is still relevant. It starts with a technical perspective, introducing many important parameters in the camera and their interconnections, then progressively introduces the key concept of "tone" in photography, extending to the essence of "highlighting the subject," and finally discusses key factors to consider for some basic types of photography.

This might differ from the majority of the "how to compose" articles or "how to adjust colors" videos you would find on Xiaohongshu (also known as Little Red Book) or Bilibili. In fact, this article doesn't mention much about the artistry of photography. Instead, it feels like a very "programmer"-like article—I saw it full of techniques, and it was quite benefiting.

This series of articles I write is actually a crude imitation and brief summarization of "Photography Notes: Photography Isn't That Hard to Learn". Even if you are willing to read my articles, I still recommend that when you have time, to click the above link, download the PDF to your local storage, and slowly read it through. Although seasoned photographers might scoff at it, as a beginner, you will surely benefit enormously—since photography is a hobby that is a lot more about satisfying yourself than pleasing others, why take the naysaying of veterans too seriously?

How Cameras Work

A simple search can yield numerous articles and videos explaining the workings of digital cameras.

Typically, they start by categorizing digital cameras into different types such as DSLR and mirrorless, then explain the principles of each type, and might even include diagrams depicting the light paths. More complex articles might also introduce the technical design of smartphones and special cameras like TLRs (Twin Lens Reflex) or rangefinders.

But I won’t make it that complicated; instead, I will summarize some key points:

1. Most of the digital cameras currently on the market are mirrorless, and Sony's "Alpha" is one of these mirrorless types. “Alpha” is a trademark registered by Sony, so others cannot use that term.
2. No matter the type of camera, even film cameras or smartphones, at their core, they all function by allowing light to pass through a series of lenses and mirrors within the lens to refract and reflect, projecting onto a fixed-size image sensor.
3. Most digital cameras and smartphones you can purchase today use CMOS sensors, unless you’re specifically buying a CCD camera for "vintage" reasons (not recommended), in which case the sensor is CCD; for film cameras, the image sensor is the particular section on the film, and for instant cameras, it's the instant film itself, which should be easy to understand.
4. The main difference between DSLRs and mirrorless cameras (including Alpha) lies in how you can see the real-time image projected onto the sensor. Usually, there are two methods: directly reading the information from the image sensor, or splitting the light path to direct part of it. The majority of modern digital cameras, including mirrorless cameras and smartphones, use the former mode.
5. When actually taking a photo, the camera first blocks all light from reaching the image sensor, then briefly allows light to pass through for a short time, and captures the image as sensed by the image sensor during that interval. This period is also called the "shutter speed."

The second point is the most important. Even if you don't understand anything else, just knowing that a camera is a device that projects light onto an image sensor through refraction and reflection and that it collects light for a short duration to produce a photo is sufficient.

Basic Parameters of Digital Cameras

Any digital camera or digital photography/video device hinges on several fundamental parameters.

As repeatedly mentioned, a camera is a device that refracts and reflects light followed by creating a photo via the image sensor. Thus, almost all main parameters are related to "light," adjusting the characteristics of light, while some parameters are concerned with the "image sensor," modifying sensor characteristics.

Following, I will introduce several camera parameters, which generally fall into two categories. One category relates linearly to the amount of light that is let in—that is, a change by a factor of $x$ in the parameter value changes the amount of light let in by the same factor. The other category has a quadratic relationship with the amount of light, meaning a change by a factor of $x$ in the parameter value changes the light amount by a factor of $x^2$. You may not be able to remember all types of parameters at first, but that's okay. There aren't too many parameters, and you will gradually become familiar with and remember them as you continue taking photographs. Ultimately, recalling them is crucial because, in manual mode, you need to inversely adjust two out of these parameters to keep the light amount constant while achieving changes in other aspects to realize specific stylistic goals.

Two Key Elements Affecting Light Intake: Shutter and Aperture

Typically, the most common parameters that directly influence the light and shadow of a photo are the shutter and aperture.

The shutter is the most straightforward parameter, also known as “shutter speed,” and is represented by a time value, like 1/100 second. As mentioned before, this is basically the time during which the image sensor actually receives light. Before and after this period, the sensor is sealed inside a light-proof box.

It's clear that the longer the shutter speed, the greater the amount of light that enters the photo, and this is, of course, a linear relationship (twice the shutter speed corresponds to twice the amount of light).

The aperture directly controls the size of the opening through which light enters. A larger aperture permits more light in, and a smaller aperture lets in less light. But the aperture is the most unique parameter (I promise there will be no more such parameters, so please remember this one!): the smaller the aperture number, the greater the light intake!

This is because of the definition of aperture, which is essentially a reciprocal of the aperture diameter. Here I could share articles like Equivalent Aperture: Yes or No?, but I sincerely do not recommend beginners start by reading about this aspect.

I’ll reiterate one last time: this is the only parameter where a smaller number means more light is let in. In the beginning, simply remember this point.

Moreover, since the aperture reciprocal is linearly related to the opening's diameter, and since the amount of light is related to area, it's clear that the relation between aperture and light intake follows the square relationship mentioned earlier.

In summary, when the aperture number changes to $1/x$ of its original, the amount of light changes to $x^2$ times the original. For example, if my current aperture is F2, and I want to double the amount of light, I should adjust the aperture to F1.4 (because the square of 1.4 is approximately 2). By the way, you might have noticed the aperture values are indicated with an F followed by a number, such as F1.4, F2, F2.0, are all correct ways to write it.

Struggling with Calculation? Let Stops Help!

Since dealing with precise values can be tedious, most camera parameters aren't infinitely adjustable but are changed in steps or "stops."

For instance, when adjusting the aperture, the typical stops you can select from are F1.4, F2.0, F2.8, F4.0, F5.6, F8.0... You'll notice that each step is roughly 1.4 times that of the previous one. Based on what I previously said, this means each step allows half the light of the previous setting.

Shutter speed may offer finer adjustments. Apart from steps like 1/100, 1/200, 1/400—each step corresponding to twice the light—a camera may also feature one-third stops or even more granular settings. Shutter speeds are more intuitive than apertures, so this doesn’t pose a significant issue.

In most cases, all you need to remember is that each aperture stop represents a difference of twice the amount of light. Forget all the formulas mentioned earlier. When you increase your aperture by one stop (for example, from F4 to F2.8), ensure that you correspondingly decrease your shutter speed or the other parameters discussed later by half (for example, from 1/100s to 1/200s) to maintain the total amount of light that gets in.

Sensitivity, Noise, and Noise Grains

Exposure sensitivity is a somewhat unique parameter. It represents the sensibility of the image sensor (CMOS or film) to light—the more sensitive it is, the less light is needed to produce an image with a certain brightness. The sensitivity value is typically indicated by ISO, for instance, ISO 100, ISO 200, ISO 3600, etc.

In practical terms, changes in sensitivity, like shutter speed, are directly proportional to the final image brightness. However, this concept cannot be explained as “enlightening” because, at the moment light is projected onto the sensor, the amount of light is most definitely set and cannot be altered. But it does have a similar effect to increasing the amount of light under situations where due to various objective facts the amount of light cannot be adjusted, which is referred to as increasing the sensitivity to light.

But if sensitivity is so useful, why not just max it out?

This is because, in our real world, various types of noise always exist to some extent. Generally speaking, the higher the temperature, the more active the random motion of particles and thus the greater the noise. However, unless temperature reaches absolute zero, noise is an objective reality that always exists. Excessive noise detected by the sensor manifests as colorful grains—noise grains—on the resulting photos.

The magnitude of noise is only related to temperature and duration of interference and is independent of optical parameters like aperture. To put it simply, let’s say we shoot with an enlightening amount of 100, producing noise of 1; we then double our enlightening amount to 200 by increasing the aperture size, the noise still remains at 1.

However, when we increase exposure time (adjust shutter speed) instead of aperture, the enlightening amount will increase proportionally to the noise. For example, if we adjust our enlightening amount to 200 by doubling the exposure time, the noise will roughly increase to 2. Because noise is random, the increased noise may not always add up with the original noise, and as long as the exposure time isn't too long, the visual impact is usually acceptable. That said, night long-exposure photographs (like those taken with 10 or 30 seconds or even longer) inevitably require us to consider the effect of noise grains.

Sensitivity presents an even greater challenge. Increasing sensitivity means increasing the sensor's sensitivity to light during that timeframe—which includes not just incoming light but also amplifies noise. What's worse, since the time has not been extended, this amounts to the original noise being magnified on the spot.

Let's revisit the example above. By raising the ISO from 100 to 200, we increase the sensitivity to light to 200, but the noise also ups to 2 and effectively stacks on top of itself; theoretically, this outcome is worse than extending the exposure time.

Thus, if it's not absolutely necessary, we should set the sensitivity to the lowest possible value—some cameras start with ISO 100, others with ISO 50… Right? Wrong!

First, even when you want to use the lowest sensitivity, try to avoid using the ISO 50 setting. At the very least, as of my limited understanding in 2024, the normal lowest setting for most cameras is ISO 100. ISO 50 resembles a special ISO achieved through electronic gain and might not be as effective as ISO 100. It's generally meaningless within most shooting settings you’ll encounter daily.

Secondly, modern cameras have made significant strides in noise removal. Even for photos directly developed by the camera (without any post-processing on a computer or smartphone), noise grains are not very apparent up to ISO 3200, even ISO 6400. Moreover, with the prevalence of AI technology, post-processing software like Photoshop can effectively eliminate noise grains. Even if your original shot seems quite grainy, it can be edited into a usable state afterward. Therefore, ISO 12800 or even higher is not entirely unfeasible in extremely low-light conditions where it's not possible to steady the camera. After all, capturing the moment is always more important than perfecting the photo.

Conclusion

I originally planned to introduce all parameters, but as I began writing, I realized it would be too lengthy, so I’ll discuss certain parameters in the next edition.

In this article, you have learned:

• A camera simply projects light onto an image sensor via refraction and reflection, then the sensor gathers light for a brief period to ultimately produce a photo.
• The shutter is the simplest parameter, expressed as 1/100 second or 1/100s, and it has a linear relationship with light intake and sensitivity to light—twice the shutter speed corresponds to twice the light and sensitivity.
• The aperture is the most peculiar parameter, written as F1.4. Its reciprocal is related to light intake in a quadratic manner—about 1.4 times the aperture corresponds to half the light intake and sensitivity.
• Sensitivity, notated like ISO 1600, has a similar effect to the shutter, but it doesn’t impact light intake, only the final sensitivity to light—twice the sensitivity corresponds to twice the sensitivity to light.
• Noise grains in photos are inevitable, and they’re related to shutter time and sensitivity but not aperture—the higher the sensitivity and the longer the shutter time, the more noticeable the noise grains.
• The majority of the camera's sensitivity settings are usable; noise grains are generally minimal. Even if noise grains are present, they can be substantially removed via post-processing. However, do not utilize the special sensitivity ISO 50.

In the following article, you will learn:

• What is the focal length of a camera
• The measurement and role of ambient light brightness
• The meaning and function of exposure compensation
• The impact of different sensor sizes on lens focal length parameters