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I had dust inside a push pull zoom. I never noticed anything. I think the main issue with dirt is if sunlight hits the dust on the lens it can do some additio

I had dust inside a push pull zoom. I never noticed anything. I think the main issue with dirt is if sunlight hits the dust on the lens it can do some additionaly flaring. I don't use lens caps either, but put a clear filter on the lens. Resale value is hurt with scratches...

azhenley 8y ago
It is really, really hard to scratch a [modern] lens. Tony Northrop demonstrated this by stabbing the lens with a knife repeatedly and it never left a scratch. UV filters though degrade image quality. Why buy nice glass just to put a “protective” filter on it that gets in the way of the image?! The real concern is decentering the lens by dropping it, but no filter will protect it from that.
- rangibaby 8y ago
  I think filters are useful as dust / junk collectors, especially modern ones with repellant coatings. The less you clean your real lens the better. The front glass is tough but not airtight so when you clean or dust it there is a real chance of introducing dust or water into the rest of the lens. Clear filters can’t hurt IQ other than introducing flare or ghosts in backlighting. It’s possible to crack or scratch your front element with minimal to no effect on your picture; a clear piece of glass isn’t going to do anything.
  - breischl 8y ago
    >Clear filters can’t hurt IQ other than introducing flare or ghosts in backlighting. Or causing fringing, or reducing sharpness, or reducing contrast... The absolute _best_ that a filter can do to IQ is nothing. But that's basically impossible. Every air/glass interface causes reflections, and no piece of glass is optically perfect. So it's going to hurt your IQ, the question is merely how much, and whether it's worthwhile. I used to use them. Then I decided I was probably never going to get much of anything reselling my lenses, so I might as well just use them instead of trying to baby them. Haven't had a problem with that decision, but YMMV.
- m0zg 8y ago
  The only time I put a filter on is when I shoot on the beach. Dried up saltwater spray is not good. Otherwise, I just use the lens cap to protect the lens. It's not safe to leave the cap off anyway even if you do have a filter: you could point your camera at the sun and damage the sensor (or shutter if it's a film camera).
- KineticLensman 8y ago
  > The real concern is decentering the lens by dropping it, but no filter will protect it from that. I've been saved by an ND0 filter when I bashed the lens against a rock. It destroyed the filter's screw thread but the len's wasn't damaged. I also once while whale watching got 'steam blasted' by a humpback whale that exhaled while scratching it's back on the boats keel. I was able to quickly unscrew the steamed-up filter and carry on photographing. Edit - This is also why I religiously use the lens hoods - if nothing else they form a sacrificial protector.
- mizaru 8y ago
  Not a knife but a crab claw, which did result in some visible (on the glass) scratches: https://youtu.be/YcZkCnPs45s?t=581 https://youtu.be/YcZkCnPs45s?t=581

azhenley 8y ago

It is really, really hard to scratch a [modern] lens. Tony Northrop demonstrated this by stabbing the lens with a knife repeatedly and it never left a scratch. UV filters though degrade image quality. Why buy nice glass just to put a “protective” filter on it that gets in the way of the image?! The real concern is decentering the lens by dropping it, but no filter will protect it from that.

rangibaby 8y ago
I think filters are useful as dust / junk collectors, especially modern ones with repellant coatings. The less you clean your real lens the better. The front glass is tough but not airtight so when you clean or dust it there is a real chance of introducing dust or water into the rest of the lens. Clear filters can’t hurt IQ other than introducing flare or ghosts in backlighting. It’s possible to crack or scratch your front element with minimal to no effect on your picture; a clear piece of glass isn’t going to do anything.
- breischl 8y ago
  >Clear filters can’t hurt IQ other than introducing flare or ghosts in backlighting. Or causing fringing, or reducing sharpness, or reducing contrast... The absolute _best_ that a filter can do to IQ is nothing. But that's basically impossible. Every air/glass interface causes reflections, and no piece of glass is optically perfect. So it's going to hurt your IQ, the question is merely how much, and whether it's worthwhile. I used to use them. Then I decided I was probably never going to get much of anything reselling my lenses, so I might as well just use them instead of trying to baby them. Haven't had a problem with that decision, but YMMV.
m0zg 8y ago
The only time I put a filter on is when I shoot on the beach. Dried up saltwater spray is not good. Otherwise, I just use the lens cap to protect the lens. It's not safe to leave the cap off anyway even if you do have a filter: you could point your camera at the sun and damage the sensor (or shutter if it's a film camera).
KineticLensman 8y ago
> The real concern is decentering the lens by dropping it, but no filter will protect it from that. I've been saved by an ND0 filter when I bashed the lens against a rock. It destroyed the filter's screw thread but the len's wasn't damaged. I also once while whale watching got 'steam blasted' by a humpback whale that exhaled while scratching it's back on the boats keel. I was able to quickly unscrew the steamed-up filter and carry on photographing. Edit - This is also why I religiously use the lens hoods - if nothing else they form a sacrificial protector.
mizaru 8y ago
Not a knife but a crab claw, which did result in some visible (on the glass) scratches: https://youtu.be/YcZkCnPs45s?t=581 https://youtu.be/YcZkCnPs45s?t=581