What you need to know about lens, sensors and light fall-off.

Ok i have a report to write but am in absolutely no mood. So i will expend the remaining energy i have in writing this short piece.

Ever wonder why people complain about vignetting on their images and what the hell is vignetting? Well, it is caused by this phenomenon called light fall-off onto the camera sensor. This is most common with wide lens.

Lenses have some degree of light fall-off, meaning that when transmitting light from the front of the lens into and onto the camera sensor, not 100% hits the sensor.

Some light is unable to reach the sensor and this usually happens on the four corners of the sensor. This causes vignetting (slightly darker exposures on four corners of the image).

AND, for reasons beyond me, light fall-off has got to do with your aperture settings. (Go ask other more techy pro people if you insist on finding out).

So looking the images i have attached, shot with 24mm f2.8, you can clearly see the horrors of all horrors, massive vignetting on the image. Some pros like the dreamy effects, others like Clubsnap photographers don’t.

But rectifying the problem is simple if you shoot in raw and uses Adobe Camera Raw on Photoshop. For that part, go and figure out on your own. Thankfully results (2nd and 3rd image) show that not much image quality is compromised.

The more sensible way is not to shoot with your aperture setting wide open. Generally when you stop down by one stop, the amount of light fall-off decreases drastically.

The forth image is shot at f8.0 without any photoshopping. Most photographers (landscapes) i know prefer to shoot at f8 or f11 anyway so they don’t really have much issue with it.

Just thought that for those who like to fix a wide lens once in a while for walkaround shoots, this might be a piece of useful information