If you currently own an APS-C camera, then it likely has a 1.5 or 1.6 crop factor. In a nutshell,itdescribes the size difference between a 35mm full frame (film) and your DSLR’s sensor.
Have a quick look at the image below.
Basically when shooting with a APS-C (crop) camera, it captures less than a full-frame sensor camera. And because of the narrower view of angle, you get an impression that a longer focal length had been used (as if it was zoomed in on purpose).
I want you to remember about this when choosing the lenses because their focal lengths are set in accordance with full-frame 35mm sensors.
50mm on full-frame sensor DSLRs
The nifty-fifty is considered to be a standard lens on full-frame (FX) cameras and you could use it in a variety of photography genres.
A lot of photographers use this prime because they like that it’s one of those that closely resemble the perspective of the human eye.
(Although, a 43mm corresponds more to the human eye but such lenses are rare.)
50mm on crop sensor
While the 50mm might be versatile for FX cameras, it’s not the case with APS-C sensor DSLRs.
Technically this glass will continue to display what you see, but the frame area itself will decrease in proportion to the size of the given sensor.
In the pic earlier, it seemed “zoomed in” solely because the cropped sensor captures less area than a full frame sensor.
Another example of a crop factor below:
As you can see, when shooting at the same focal length on a full-frame vs. APS-C sensor, the frame area is significantly different.
The viewing angle also changes on a crop sensor.
Therefore it would be incorrect to say that the 50mm on APS-C is same as 75mm (50mm x 1.6 crop factor) on a FX camera. Instead, it’s more accurate to say that the viewing angle of a nifty-fifty corresponds to 75mm on a crop.
If a nifty-fifty is pretty universal on a full-frame, then it becomes too narrow on a crop (in terms of photography uses/genres), so it’s likely you won’t be satisfied with it as much.
50mm on a crop = great portrait glass?
Here’s the thing:
Some people say that 50mm on a crop sensor camera is a portrait lens. It’s not exactly so.
As I mentioned earlier, only the viewing angle changes. However, this prime is not the best choice for shooting full face photos due to sufficient distortion.
(Remember that a nifty-fifty on an APS-C camera might be too wide and you’d have to get in tight and introduce more distortion.)
This being said…
If you own a APS-C (crop) sensor DSLR, it’s probably best that you do not get a 50mm prime. So, what to get then?!