Maybe I will make these into a series if I manage to find more things to complain about, but for now I would like to rant about …
Focal length, sensor size and how they truly affect your photos
Disclaimer: I have been brooding over this subject for a few months and I am not saying that what I typed here is absolutely correct, but I feel they would serve as
Due to the lack of equipment (money), we will have to do a lot of thought experiments instead of
The analogy
Imagine you are the most skilled photo-realistic painter in the entire observable universe and you would like to paint the scene infront of you and mail it to your friend. How much of the scenary you are able to share with your friend depends on the 3.5 factors:
Factor 1 - How much of the canvas you can reach. Stand infront of the canvas and extend out your arms to their maximum possible length. That will be the limit of how much you can paint on the canvas without moving.
Factor 2 - How “big” you want to paint everything. Maybe you want to magnify everything by 10x in your painting, eg. a 1 meter tall tree will be 10 meters tall in your painting.
Factor 3 - The size of your canvas. Just because you are the best painter does not mean you have unlimited paper. Or maybe you purposely chose a smaller piece of paper for your artistic vision. Who knows.
Factor 3.5 - How far away you stand. The closer you are to a scene, the less you are able to see and therefore replicate in your painting. The further you are away, the more you can see and thus paint to show to your friend. But this rule applies “linearly” no matter how you alter the 3 main factors above so we will not talk about this in detail.
With the analogous factors above, it should be easier to have thought experiments regarding focal lengths and sensor size by thinking of it in terms of paiting. Now I shall explain what each factor represents in photography terms:
Factor 1 - This is akin to image circle, the illuminated area that is projected by your lens. This is a fixed factor that is dependent heavily on lens design and cannot really be changed, just like the length of your arms.
Factor 2 - This actually refer to the focal length, because focal length decides the size of objects when projected onto your sensor. I have decided to abondon the mainstream notion that focal length = field of view (for this article) due to reasons I will explain later on.
Factor 3 - This is an analogy for sensor size. There are a few standard sizes for camera sensors in the industry, full-frame (FF) and APS-C, which is 1.5 times smaller than FF.
Scientific Definition: The distance between point where all the light rays converge and the camera sensor.
Colloquial Definition: How much the camera can “see” and how much “magnification/zoom” a lens has. For example, everyone knows that a 14mm captures a wider scene than a 28mm. And a 200mm lens produce images that are very “zoomed in”. It is basically ingrained in all photographers that a smaller focal length means wide and the more you increase the focal length, the more zoomed in/magnified your scene/subject is.
Image Circle
Colloquial Definition: Imagine (or actually try it out) that you place a lens infront of a very dark piece of cloth. The circular “image” you see on the cloth is what is called the image circle.
Sensor Size
Colloquial Definition: The area of your camera that is sensitive to light. The most common “sizes” are APS-C, full frame and medium format. A full frame sensor is 36mm * 24mm but for reasons that is rooted in film history, full-frame sensors are also sometimes referred to as “35mm sensor”. APS-C sensors are smaller by 1.5 to 1.6 times smaller, depending on the camera brand. Medium format sensors are larger than full-frame. How much larger? Once again it depends on manufacturer. Full-frame sensors are 0.79 times the size of Fujifilm’s GFX “medium format” sensor / Hasselblad’s X series of cameras. However, when compared to Hasselblad’s H series of medium format sensors, full-frames are only 0.64 times as large.
Crop Factor
Colloquial Definition: The area of your camera that is sensitive to light. The most common “sizes” are APS-C, full frame and medium format. A full frame sensor is 36mm * 24mm but for reasons that is rooted in film history, full-frame sensors are also sometimes referred to as “35mm sensor”. APS-C sensors are smaller by 1.5 to 1.6 times smaller, depending on the camera brand. Medium format sensors are larger than full-frame. How much larger? Once again it depends on manufacturer. Full-frame sensors are 0.79 times the size of Fujifilm’s GFX “medium format” sensor / Hasselblad’s X series of cameras. However, when compared to Hasselblad’s H series of medium format sensors, full-frames are only 0.64 times as large.