2005-03-08 kl. 17.52 skrev Qkano:
<<<One is an UV filter to protect the lens in really adverse conditions (leaving it on the lens all the time is bad practise, like playing a violin without removing it from its case), the other would be a polarizer, whose effects would be difficult to simulate in PS afterwards.>>>
Per
1) The polarizer is impossible to simulate in PS.
Literally, yes of course, since the info about polarizing of the photons has gone the way of Shrodinger´s cat. A few of the more obvious photographic effects, like dark skies and toned-down reflections CAN be simulated with some hard work.
2) The UV filter has me guessing.
Are CCD, or for that matter CMOS, sensors particularly sensitive to UV in the same way colour film was? Obviously any overall haze caused by UV cannot be undone later. It's not a simple matter of colour balance
Well, I didn´t refer to its actual filtering effect (which is minimal anyway with today´s lenses; an uncoated Tessar was another thing), only to its physical protection (which would be EXTREMELY hard to simulate in PS afterwards....;-> ).
3) For mild colour balance effects the only real reason for using a filter is I guess to reduce the amount of work post capture (remembering to turn auto-colour balance off). For an *extreme* colour cast you are trying to correct there is a lot of sense in correcting it first - presenting the sensor with a balanced mixture of wavelengths. But this extreme is probably beyond anything we meet in outdoor photography.
Agreed. Putting on a filter for a shooting session is less work, and theoretically better, than correcting 75 raws later, even if you batch them. Only, chances are the filter won´t be exactly what you need, so you´ll have to run that batch job anyway...
Per Öfverbeck http://foto.ofverbeck.se
