View single post by jk
 Posted: Mon Jun 24th, 2019 16:21
jk



Joined: Mon Apr 2nd, 2012
Location: Carthew, Cornwall, United Kingdom
Posts: 6877
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novicius wrote:
I Fail to Understand why the use of ND filters,..here in Europe light level is rather low, f.ex. , in summer ,100 iso at 100sec. between 2 - 4 midday usually requires f11...equally ,6400 iso at f1.4 , a difference of six f stops could be used ,which is easily overcome by today´s camera`s..and anything in between, enabling the photog to play with DOF,..and as mentioned , they`re supposedly polarizers, so why then not resorting to those, since you seem to have them already anyway..?..
It is not DOF that is desired to be controlled but shutter speed.  If you want the sea or water to blur then you need 1/4 or 1/8 second at ISO 100/200 at normal f8 aperture for best sharpness from lens.  You need to use ND to get these shutter speeds.  I find I need ND of 4 stops.  This would mean changing to ISO6/12 (not possible on current cameras).

Many variable NDs are two polarisers working in opposition but these give colour casts (brown/green) also polarisers ate not good when used on wide angle lenses.   Many landscape photographers use flat ND filters but these are expensive for a superwide angle 14mm as you need a 150x150 or 150x175mm.

Going later in the day may be impractical or the light angle changes so the photo does not work.



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