Originally posted by estudleon Hi, Ben_Edict
Yes, I agree when you limited the question to the beneficts in the blue and UV light case.
But this is only argument to the UV filter, and in this way, my guesswork about the rest of the filters is true.
But the quid that you refer, not the only to have in consideration
In the case of the UV filter, don't forget that you are adding two air-glass surfaces to the existents in the lens, and then the internal reflections and the
ghost images increase.
And with the filter in the front, the optical formula of the lens alters when modifying itself the diffraction and refraction of the optic system, losing something of his contracts and shaprness.
I fully agree with your reluctancy about the general use of filters, as the two additional surfaces need necessarily degrade the image. In my own experience though, this is not visible (to my eyes), if the best filters are used. But I do make some caveats:
i.e.
- I remove filters when shooting against bright light
- never use filters for nighttime shooting
- remove them in the studio
- never combine filters, thus I remove any UV filter, if I need a polariser
. always use a lens hood and (if necessary) additional shielding, to prevent increased flare caused by the filter
Anyway, as filters should be plano-parallel (high quality filters are that within technical limits), then it does not affect diffraction. So the loss of sharpness and contrast, which is absolutely there, can be so minimal, that it is not visible under standard shooting conditions.
Ben