What are the differences between different sized sensors?
(A continuation from part one, where we discussed the difference between DSLRs and other cameras, and the benefits of a larger sensor.)
Different models of DSLR cameras come with sensors of various sizes.
The most expensive professional DSLRs have what are called Full Frame sensors. They are called this as they are the approximate size of the old 35mm film negative, and so are considered full 35mm frame size.
Most entry level to mid range DSLR’s have what is known as an APSC sensor. This is usually ¾ of the size of a full frame sensor. (although Canon APSC sensors are slightly smaller) The advantages of an APSC sensor include lower cost and lighter weight cameras and lenses.
Sharp from front to back
Full frame sensors generally have the lowest noise at higher ISO’s and resolve superbly fine detail.
One of the biggest difficulties inexperienced photographers face when they first move to DSLR cameras is getting perfectly sharp images. This is because the higher the pixel count and the larger the sensor, the more spot on your aperture and focus distance needs to be.
This is why you will often hear of inexperienced photographers who splashed out on a DSLR because they thought it would make them a better photographer, only to be sorely disappointed.
They will complain that they got sharper images from their compact cameras and even suggest that the DSLR is not as good. This is however all user error.
With a small sensor on a compact camera you can focus anywhere using any aperture and most likely always fluke a sharp image from front to back. There is no skill involved hence why they are referred to as 'point and shoot' cameras.
With a DSLR you have to know how to use your equipment and how to correctly set your aperture for the shot. You need to know how close you can focus on an object and still keep sharp focus in the background; and what aperture will achieve this. In other words, don’t even bother with a DSLR until you know how to use it. You will just look like a fool with an expensive camera.
So the smaller the sensor the more of the image that stays sharp from front to back. It is actually really difficult to achieve any blurring effects with a small sensor, which is another disadvantage of compact cameras if you want to get creative with highlighting your subject and blurring the background. This is especially important for portraits and wildlife photography.
The largest sensors can most easily achieve shallow depth of field and selective focus. This is also why they are the most difficult to use for front to back sharpness. It is therefore recommended that you don’t outlay for a top model full frame sensor until you are confident with nailing aperture selection and focus, as you will only end up frustrated with disappointing results.
An APSC sensor is a perfect compromise for photographers with intermediate skills. You can achieve creative blurring effects and will still need to know how to use your camera. However there is a little more margin for error with focusing distance.
Beach from above
Even if you are still learning, it is better to buy a mid range DSLR that you can grow with as your skills improve, rather than buying an entry level model that you may outgrow too quickly as your skills develop.
In Part 3 we look at the pros and cons of full frame vs APSC sensors for different styles of photography and also discuss the importance of decent lenses for image quality.