Full Frame vs Crop sensor Depth of field comparison (DoF)

We've all been hearing about the differences between 35mm Full Frame cameras and the very popular crop sensor (Aps-c) cameras . The thing that interests me however is the depth of field. Unfortunately this topic doesn't get covered very often and it makes a huge difference in my opinion.

With 35mm Sensors you get the actual focal length of your lens. With aps-c sensors you get a narrower view through the same lens because the sensor is smaller. So with a 50mm lens you actually have a view similar to that of a 75mm lens on a Nikon Crop body. Please note that the focal length does not change it just gives you an enlarged area in the middle.

What this basically means is that you need to get closer to your subject with a full frame camera. We all know that getting closer to our subject decreases the depth of field. So in theory full frame cameras should have the advantage if you want to isolate your subject from the background.


We can also then determine that with a crop sensors you will get more depth of field because you have more working room. This doesn't seem to make much of a difference to most professionals as they can always get everything in perfect focus with landscape photography. What you can't however do is get less depth of field. Unless of course you can afford a Tilt Shift lens.

So in my search of this topic I stumbled across this page by Bjorn which is very informative.
http://www.naturfotograf.com/D3/D3_rev06.html

As you can see from his test there is about a 1 stop difference between the backgrounds. As stated by Bjorn the differences are there but very small.

Now lets look at the Nikon 85mm f1.8 lens and compare it to the 85mm f1.4 lens. There is a difference of only two thirds of a stop. But the 85mm f1.4 lens is used by the worlds best portrait photographers. It costs three times as much and it isn't even as sharp as the f1.8 version. They pay that money solely to get a smoother background.

Do you think 1 stop makes a difference?

Well that depends really on the lens. If you are shooting with a cheap lens the Bokeh isn't very pleasing to begin with but if you are shooting something like a f1.4 I think you might just benefit a great deal from a full frame camera.

Happy Shooting!