In this article I’ll try to explain how sensor size influences focal length. When you decide to buy a new camera or a new lens, these things are very important. There is also the chance to buy some lenses that may do not fit with your camera and it would not be too pleasant for you so beware.
Sensor size. First of all let’s do a quick review about sensor sizes. Sensor sizes currently come in different sizes, depending on their use, price and desired. Below you can see the relative sizes of various sensors:
Canon’s 1Ds/5D/6D and Nikon D3 series are the most common full frame sensors. Canon cameras such as the Rebel/70D/7D all have a 1.6X crop factor, whereas mainstream Nikon SLR cameras have a 1.5X crop factor. There are also bigger sensors that are used on more expensive cameras like Hasselblad (medium format sensor). On smart phones and other compact camera we can find smaller sensors from ~1/4” to 2/3”.
Focal length and angle of view
The focal length of the lens is the distance between the lens and the image sensor when the subject is in focus. This length is generally indicated in mm (e.g. 18 mm, 35 mm, 50 mm). For zoom lens you will find two values, one for minimum focal length and the other for maximum focal length (e.g. 16-35 mm, 18-55 mm, 70-200 mm).
The angle of view is the visible extent of the picture captured by the image sensor, stated as an angle. Wide angle of views capture greater areas, small angles capture smaller areas. Changing the focal length changes the angle of view. The shorter the focal length (e.g. 16 mm), the wider the angle of view and the greater the area captured like in landscape photography. The longer the focal length (e.g. 200 mm), the smaller the angle and the larger the subject appears to be.
Crop factor and focal length multiplier.
When we say “crop factor” we refer to the sensor’s diagonal size compared to a full-frame 35 mm sensor. It is called this because when using a 35 mm lens, such a sensor effectively crops out this much of the image at its exterior (due to its limited size). With crop sensors we can find both advantages and disadvantages. The greatest benefit is when we want to approach as much as we can to main subject. A standard 100 mm lens on a 1.6x crop factor it become 160 mm lens! Another good part is that the sensors use more of the lens center, which is sharpest, while quality degrades progressively toward to the edges. This is one reason that involves to buy sharpest lens as you can afford on a full frame format camera. On the other hand, a full frame sensor can provide a much better dynamic range and better low light with high ISO performance. Another think that you must consider is that a full frame DSLR will have a shallower depth of field because larger the sensor is, the longer the focal length required to create the same field of view, hence a shallower depth of field is created due to the additional focal length which can be a good think especially in food photography. In conclusion, we can say that a full frame sensor DSLR and a crop sensor DSLR have their own advantages and disadvantages. While a full frame DSLR provides a bit better overall quality, a crop sensor is much cheaper.
That’s it for this post, I hope you all enjoyed and please rate this comparison!
