[rollei_list] Re: OT: B&W Filters in digital...Pola filters

  • From: FRANK DERNIE <frank.dernie@xxxxxxxxxxxxxx>
  • To: rollei_list@xxxxxxxxxxxxx
  • Date: Tue, 13 Jul 2010 15:52:56 +0000 (GMT)

The microphone analogy is extreme and absurd. The differences between film and 
digital are not that big. You still have not said what the difference is. Are 
you stating a fact which you have evidence and experience to support, or an 
opinion?
I am stating an opinion. It is that the effect, whilst unlikely to be 
identical, would probably be within the tolerance one would get from the 
variability of film from type to type, and tolerance between different filters 
of the same nominal spec.
That is to say, I would expect one to be able to get the effect one is after as 
accurately as you would on film.
The effect may not be identical, but neither would it be between 2 rolls of 
film from different batches.

--- On Tue, 13/7/10, Eric Goldstein <egoldste@xxxxxxxxx> wrote:

> From: Eric Goldstein <egoldste@xxxxxxxxx>
> Subject: [rollei_list] Re: OT: B&W Filters in digital...Pola filters
> To: rollei_list@xxxxxxxxxxxxx
> Date: Tuesday, 13 July, 2010, 13:14
> And again I will reply that there is
> a difference between filtering
> light with a green, yellow, orange, etc. before it hits the
> sensor and
> applying a photoshop filter in post-processing. The look is
> different.
> If you think about how a digital camera works, it would
> have to be...
> 
> There are photoshop filters which attempt to mirror the
> characteristic
> curves of classic b/w emulsions. They help but again are
> not the same
> as shooting the emulsions. This remind me of ProTools
> plug-ins that
> supposedly make your 30 dollar boom headset mic sound like
> a U-87...
> 
> 
> Eric Goldstein
> 
> --
> 
> On Tue, Jul 13, 2010 at 2:52 AM, Frank Dernie
> <Frank.Dernie@xxxxxxxxxxxxxx>
> wrote: (snipped)
> 
> > Do not forget, however, the original question was
> whether one would need to use green, yellow, orange, etc.
> filters used in B&W film photography to get their effect
> in B&W digital photography. Many subsequent responses
> have drifted away from the original thread (as usual on the
> internet...)
> >
> > In the case under discussion (ie the original query) I
> am sure that on a non-clipped digital colour file the effect
> of any filter on the converted-to-black-and-white version
> can be produced to an acceptable level of consistency (ie at
> least as good as the effect of the same filter on different
> B&W films, or at different exposures). It would probably
> be easy to exactly replicate the effect mathematically as
> long as the precise filter characteristic is known, though I
> have no idea whether Photoshop has an easy way to do this.
> >
> > Whether one would actually want to do this rather than
> use a filter is up to the user!
> >
> > cheers,
> > Frank
> >
> > On 13 Jul, 2010, at 02:04, CarlosMFreaza wrote:
> >
> >> 2010/7/12 Laurence Cuffe <cuffe@xxxxxxx>:
> >>>
> >>> What about a Pola-Screen? I can not find a
> >>> reference to polarization in the IB for my
> camera.
> >>>
> >>> Marc
> >>>
> >>> Yes good point. Thats another glaring
> exception to the notion that it can
> >>> all be done in Photoshop.
> >>
> >> Regarding a polarizing filter for PS and others
> image edition
> >> software, it's necessary to distinguish two main
> practical effects you
> >> can obtain from a regular true polarizing filter
> used during the image
> >> taking. The effect to obtain deeper and darker
> blues for the sky and
> >> for the greens, etc. can be obtained using PS or
> similar software
> >> judging the image after to take it, you don't need
> a Pola-Screen for
> >> this case. It can be done working with the R-G-B
> channels in PS or it
> >> can be easily done with simpler tools like the Sky
> graduated filter
> >> from Picasa. This is a method for PS:
> >> http://photoshoptutorials.ws/photoshop-tutorials/photo-effects/polarizing-filter.html
> >>
> >> However there is another very useful effect you
> can obtain from a true
> >> Pola filter (Rolleipol f.e.) that cannot be
> obtained from PS and
> >> similars; this is the effect to eliminate
> reflections from bright and
> >> transparent surfaces allowing to capture subjects
> beyond this surface,
> >> f.e you wan to capture fishes and stones within
> clean and transparent
> >> water but the reflections are avoiding to see
> them, turning the
> >> Polafilter you'll find a point where the light is
> polarized and the
> >> reflections are eliminated allowing to capture
> fishes and stones. If
> >> you want to capture the _real_ image for this and
> similar cases, you
> >> need to use the filter during the image taking, PS
> cannot invent the
> >> real subject.
> >>
> >> Carlos
> >> ---
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