Camera Tech: Sensor Size’s

Big or small, what’s better? More importantly, you should be asking yourself, what’s best for you?

Let’s start by talking about different sensor sizes. In the early days of film there were a few major sizes of film that became popular which have since stuck around as the major sizes in use today. Firstly, there was large format or sheet film. This included most of the old wooden boxes where you could see someone hiding under a curtain behind the camera, and while there have been digital cameras made in these formats, they are not hugely popular or the most practical option.

Secondly there is medium format, this used 120 or 220 film and included cameras that shot 6×6 (like the Hasselblad 500cm), 6×4.5 (like a Bronica ETRS) or 6×7 format (like the Mamiya RB67). This was a much more practical size for photographers as the cameras could be hand held and was a more transportable option. There are still digital cameras now being produced in medium format, such as the GFX50S which shoots a size slightly smaller than 6×45 but significantly larger than 35mm or “full frame.”

This leads to the third size of film and the most popular by far, 35mm film. Again, there are different ratios. This includes half frames (as taken by the Yashica Samurai) which was used to allow for more photos to fit on one roll of film or panorama formats which did the opposite but took spectacular photos (like on the Hassleblad Xpan). However, the standard 3×2 format which most cameras adopted is similar to that of full frame digital sensors today, which can be seen in the ranges of Canon, Nikon, Sony and almost all camera brands.

Coming in forth and much later to the film scene is the since discontinued APSC size film. This sat at about half the size of 35mm and was used to make some of the smallest and most compact film cameras ever made such as the Canon IXUS. This sat significantly smaller than most 35mm compact cameras or point and shoots. There are other film sizes not listed here, but along with digital sensor sizes, with phone cameras and digital compacts constantly shrinking and challenging what’s possible, there are too many to count.

Here is where the fun begins. What does sensor size do exactly? The most obvious difference you can find is in the size of the image. This doesn’t mean the file size or the number of pixels, but rather the size of the image seen by the camera. This is called the crop factor. It’s what allows some cameras like the Panasonic TZ90 or even the Nikon P1000 to have such amazing zooms fit all into the one camera. When combined with the right lens, a small sensor can do wonderful things.

The easiest way to demonstrate the crop factor is to compare two cameras on the same lens. Here I used a Nikon D7000 (with a crop factor of 1.5x) and a Nikon D810e (a full frame or 1x crop factor) on a 200mm lens at f2.8 to take an image in the same location. As you can see, the second image which was taken on the Nikon D7000 looks almost as though it has been cropped from the first image.

Though this can help you in taking long distance photographs, it can be a hinderance when looking for a wide angle. Alternatively if you’re looking for the depth of field and bokeh without cropping in the image and losing the background. An example of this is on a wider shot where one might normally struggle to get much depth of field, a larger sensor will be able to give you that shallow depth of field.

Another difference noted by camera makers is the dynamic range of digital sensors or the range between the lightest and darkest area of the image. While film’s dynamic range depends on which film is chosen and the chemicals on the film, with digital cameras, it is the set up and the type of sensor used that determines this.

The other difference is the noise, or the little specs you see on photographs taken with a higher ISO. One of the factors in the amount of noise or using film terminology “grain” (in films case, tiny crystals forming on the film), is the amount of light each pixel can collect. This is affected by the size of the pixels and some more factors I will explain further in upcoming blog posts. This means that having a smaller sensor with the same number of pixels will mean more grain when turning up the sensitivity (ISO).

In conclusion, size does matter, but technology is trying to change that.

Computational photography is essentially, photography simulation or using processing power to improve photographs and get them closer to that of a camera with a bigger sensor or better lens. There are a lot of ways that this can be done but this too will be explored further in blog posts to come. As a teaser, here is one, portrait mode. On any of the latest iPhones, there is a portrait mode where the phone simulates bokeh to provide more aesthetic images which its cameras cannot. As seen below when compared side to side, a portrait taken on an iPhone SE of our handsome Steve has the blur that draws attention to the subject but also blurs the edges of his body and does not blur the background proportionally to the distance. Contrastingly, this looks off when compared to the portrait taken on a Nikon D500 (cropped sensor) with a 24-70mm Af-s f2.8. It can also be noted here that the perspective is different although he takes up a similar portion of the image. Thanks Steve!

That is all for this week! Stay tuned for more posts coming soon!