Fixing a Problem Lens

I may have made a mistake.

In multiple instances, I’ve noticed that my 50mm f1.8 has had some issues where bright light looks like its causing coma or trefoil aberrations.  Aberrations usually occur in non-perfect optical systems where oblique light isn’t perfectly focused on the screen (or in this case, the camera sensor.)  Higher end camera lenses can reduce or make aberrations almost negligible, hence why their optical quality is so good.  But for a $100 lens, I wouldn’t be surprised if those imperfections was just an attribute of the lens.

If you’re really observant, you can see the instances where the imperfections show up in my photos.  I usually don’t choose to publish them if they’re too obvious, but they’re there, especially in low light situations.  If you look closely, the bluish-green blobs of light are what I’m referring to.

Still don’t see it?  When I was lining up my camera in a recent shoot with the 50 mm lens, I noticed it again.  Except this time it was so obvious, it became interesting, but still too distracting to be useful for the shoot.

Fast forward a few days, a video on lenses reminded me to never put cheap filters on expensive lenses (why would you ruin the optical quality of an expensive lens with junk on the front of it?)  I knew that, but I never put two and two together.  I use a cheap Tiffen filter on my 50mm to prevent dust and scratches on the front element.  Maybe that was what was causing my problems?  So I did some test shots: one with the filter, and one without.

I’m definitely going to take my 50mm out more.  Just without the filter.