When I shoot, I like as little glass between me and my subject as possible. Obviously I need a lens, but as little extra glass as possible is good.
The reason is that glass can distort, and it can introduce extra flare.
- If glass is not optically great, this will be more easily noticeable (use drug store glasses, look though airplane windows, or old windows).
- If it interferes with filters, e.g. with a polarizer (try shooting through your car windshield with a polarizer).
- If you shoot at an angle.
When you shoot through an aquarium, for instance, do not shoot at an angle. Because this results:
Ouch. We call this “chromatic aberration”.
The solution: shoot straight, and avoid wide angle lenses.
No aberration even when you look up close.
So glass can cause problems – which is why I use as little as needed. Meaning I do not use filters on my lenses except when needed. Like “Protection”, “Daylight” or “UV” filters. Yes, I have them in my bags in case it starts raining or snowing, or I am in a sandstorm or on a beach, but unless those things are happening, I will not use them. Every little bit of clarity helps.