On 3 Nov 2013, at 18:42, Mark Roberts <[email protected]> wrote: > > Bob W wrote: > >>> On 3 Nov 2013, at 17:59, Mark Roberts <[email protected]> wrote: >>> >>> Larry Colen wrote: >>> >>>> Yup he lists exactly the situation I said you would see effects in. Other >>>> than >>>> that has any one actually done any side by side testing to see if they see >>>> any >>>> differences? Or is it just more fun to argue without being hampered by >>>> facts? >>> >>> Personally, I don't spend much time doing testing of this sort. I find >>> sources I trust – and I certainly trust Mike J for this kind of thing >>> – and go by their tests. I have experienced this kind of effect in >>> real life (I was just editing some of my shots from Ireland this >>> morning and found some examples of this caused by a polarizer in broad >>> daylight). >>> >>>>> http://www.luminous-landscape.com/columns/sm-feb-05.shtml >> >> Mike J is a good, persuasive writer, and talks a lot of sense, but what >> makes you think he's done any testing? > > If you mean formal, controlled, scientific testing, nothing. But > informal testing, his years of experience and less formal testing, > plus my own replication of the effect is good enough for me. And > likely is good enough for anyone whose purpose is real photography and > not laboratory-level quantifying of the effects. > > For those who need MTF graphs, etc. for scientific measurements then > formal tests with proper controls are in order. >
I don't mean formal tests, and I'm not referring to the internal reflections under particular circumstances which are easy to recognise and deal with, and are not in doubt, but to the supposed degradation of image quality in normal use simply by sticking a (high quality) filter in front of the lens. There's no doubt in my mind that formal testing would confirm that the image is degraded, but that is a long way from equating it with shooting through a window pane. My claim, and my years of experience back this up, is that for normal purposes nobody will be able to see the degradation without the type of equipment needed for conducting formal tests. Ergo for all intents and purposes, it does not exist and the filter does no harm. Nobody, in the 40 or so years I've been taking pictures, has ever looked at one of my photos and pointed out an image quality problem attributable to using a clear filter (other than internal reflections. Once), and I suspect it has never happened to anyone else either. On the other hand, I have used my cameras in difficult conditions, and dropped them on numerous occasions, and the filter and / or hood has taken the punishment. Since the front elements were never damaged it's impossible to be certain that the filter or hoods saved them (like the claim that a crash helmet saved one's life), but on balance I find in favour of good quality filters. But I'm not going to get hung up on it and force my opinion on others. I'll simply have naysayers hanged, drawn and quartered instead. B -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
