Any photo we are to take today is limited in clarity by the pixel count of that photo.
That is to say, a very far object might only appear as one pixel on the picture, rendering it unable to be identified.
But, if we were to take that same photo from the same location but with a strong enough telescope, then the object would be covered by more pixels, increasing its resolution and allowing us to identify what it is.
Then, assuming that there are no obstacles obstructing light, if we had a sufficiently strong telescope, we could clearly resolve an object of any distance when observing from a stationary reference point.
Yet, the distance between the object and our stationary point of observation grows exponentially in while our eye at the telescope remains a fixed cross-sectional area, resulting in a more "pixel dense" image as we increase the strength of our telescope.
This gives rise to the question: Is it possible to resolve an object infinitely far while keeping a set cross sectionary area and stationary point of observation?
In other words, how "pixel dense" is light? How much information could light carry?
Understanding the Exposure Triangle (with f-stop proof)
The exposure triangle is basically three factors that affect exposure: ISO, shutter speed, aperture.
1. ISO
This value is calculated in lumens/area, controlled by the microprocessor that determines how much analog data would be collected by each photosite which corresponds to effective pixel (because some border pixels are used to determine parameters, not for actually capturing the image).
The ISO is also split into native ISO and extended ISO. The native ISO is how light each photosite could actually hold before it spills. For example, if the native ISO goes from 100 to 4000, then each photosite could hold a maximum of 4000 lumens/area. The extended ISO goes much higher into values like 12000, or 208500 lumens/area. This would introduce a great deal of gain because the extended ISO isn't the photosite absorbing more light information, but a manipulation does by the software. I personally never go up that high and I do not recommend it as it would mess up the image.
Finally, if you were to double the ISO, you would get double the exposure. Also, exposure is counted in "stops", one additional stop of exposure is equivalent to doubling the exposure.
2. Shutter Speed
The time duration of exposure of each photosite. If your shutter speed was set at 1/100th of a second, then each photosite would be exposed to light for 1/100th of a second. Usually, the time would be a fraction of a second. Sometimes, for long exposure effects like making waterfalls look silky, you might have a shutter speed that's longer than a second.
On a mechanical shutter, the effect of rolling shutters would occur if the speed isn't fast enough. It's where an object moved while the shutter was scanning from top to bottom. Also, since the shutter scans from top to bottom but the image that comes through the lens is upside down, the lower part of the image is actually older than the top part. However, in a video camera, pixels are read from bottom to top to counteract the effect of the vertical flip from the mirror. So in those cases, the top part of the image is actually older than the bottom part.
If you were to double the shutter speed, say from 1/100th to 1/50th of a second, then you would get one more stop of exposure.
3. Aperture
This is the extremely tricky one. Aperture is measured in f-numbers or f-stops (which is not the same as a stop of exposure, though both do have the word "stop" in them).
If you have an aperture of f4, then to get one more stop of exposure, you would adjust it to f2.8. I know, it's very confusing. Why does the numerical value go down to get more exposure? Why isn't it f5.6 (which is a multiple of 2 of 2.8)? Well, when you do a google search on the internet, they would give you this following chart to reference.
where f is the f-stop, L is the focal length, and D is the diameter of the aperture.
The focal length is the distance from the focus center of the lens to the focal plane (image sensor), but for now, ignore it; it doesn't affect exposure, and for our purposes, it's constant.
The first equation is the definition of f-stop. All remaining steps use F to represent f-stop.
Basically, the idea is that double the area of the aperture, double the exposure. Now, we need to convert that idea into a number for the f-stop.
Thus, the multiple of the f-stop is the inverse square root of the multiple of exposure.
I actually made a calculation error in the example. bf on the last line should be f2.
If I started off shooting at f4, then I would get f2.8 in order to double the exposure.
Anyways, for those starting off with photography or just wanting to understand how exactly f-stops correlated with exposure, I hoped this helped.
If you have an aperture of f4, then to get one more stop of exposure, you would adjust it to f2.8. I know, it's very confusing. Why does the numerical value go down to get more exposure? Why isn't it f5.6 (which is a multiple of 2 of 2.8)? Well, when you do a google search on the internet, they would give you this following chart to reference.
This chart shows two things, the f-stops that you need to get to double exposures and that the smaller f-stops are actually bigger apertures.
What most people couldn't to explain is why.
The equation for f-stop (f) is actually this:
f = L/D
The focal length is the distance from the focus center of the lens to the focal plane (image sensor), but for now, ignore it; it doesn't affect exposure, and for our purposes, it's constant.
The first equation is the definition of f-stop. All remaining steps use F to represent f-stop.
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| How to calculate f-stop in relation to exposure |
Basically, the idea is that double the area of the aperture, double the exposure. Now, we need to convert that idea into a number for the f-stop.
Thus, the multiple of the f-stop is the inverse square root of the multiple of exposure.
I actually made a calculation error in the example. bf on the last line should be f2.
If I started off shooting at f4, then I would get f2.8 in order to double the exposure.
Anyways, for those starting off with photography or just wanting to understand how exactly f-stops correlated with exposure, I hoped this helped.
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