Been inspired by some great pics posted on here recently.
Learning at the mo with a DSLR - all v challenging ;-( I remember a lifetime ago I had a polarising filter for 35mm which gave good results. Is it worth trying with DSLR, or should I be using the camera's flexibility/capabilties to achieve similar result?
Am not competent at re-touching on the PC.
Ta
Get one, they work really well. You know you have to get a circular polariser, yes?
Can I suggest you take a look here talk photography tutorials
It's a very good forum, like STW but more friendly.
Yep. Polarising is one of the few filter effects that you can't really just add-in afterwards in photoshop - worth getting IMHO.
As samuri says, you need a circular polariser to work properly with a DSLR.
Read http://www.luminous-landscape.com/tutorials/polarizers.shtml
Worth getting. Very handy on the beach.
Anyone else using a ND gradient filter?
A DSLR's flexibility or capability won't do what a CP filter will do - neither will any image re-working application so do get one as they are very useful in the right circumstances.
There are ways to tweak a photo in Photoshop using Selective Colour and adjusting the blues, after selecting just the sky, but it's a pfaff when a polariser does the job when you take the photo.
Anyone else using a ND gradient filter?
My wife doesn't mind me fiddling and fumbling, but that has no connection to photography.
yeah there great i can see my neighbour getting out of the shower even when there's glare on the window!
thumbs up!
it is virtually impossible to unpolarized a picture in photoshop.
There are ways to tweak a photo in Photoshop using Selective Colour and adjusting the blues, after selecting just the sky, but it's a pfaff when a polariser does the job when you take the photo.
Tweaking sky simulates some of the polariser effect, but try photoshopping to remove unwanted reflections from glass or water!
Yep, I use an ND Grad as well. I use that more than the polariser to be honest.
I use the cokin P series filters. You get an adaptor to match your lens filter size then you slot the filter holder onto it and drop the filter in, very easy to use and all you need to do for different filter sizes is get a different adaptor.
Graduated filters are easier to add in photoshop but I still prefer getting that effect from the filter. You capture a lot more detail from the sky and you can get some **** awesome long exposures pictures.
Forgive my ignorance, but what does a polarising (or any other) filter do?
Cheers.
samuri - nice!
Forgive my ignorance, but what does a polarising (or any other) filter do?
A polarising filter removes reflections from non metallic surfaces. So skies look more detailed and water looks more lifelike. Stuff like that.
Other filters do other things, like the graduated filter exampes from Samurai above
(Nice pics BTW Samurai! 
)
santacruzsi
fitlers fall into three main catagories, they are placed in front of (or behind on some more obscure lenses) the lens to directly affect the light hitting the film/sensor and are therefore a permanent effect unlike filtering in software.
Colour effects will cut the amount of certain colours entering the lens so can be used to enhance or retard the appearance of certain things like the sky, grass or flesh tones
EV (or light level) effects serve to reduce the amount of light entering the lens without changing the colour (this is called 'ND' or Neutral Density). It is either a flat change across the whole frame or a graduated change across the frame (Grad ND). This means you can change the ISO/aperture settings whilst maintaining good exposure or you can lessen the effects of having a high variation of light level across the frame (like a bright sky with a dark foreground).
Special filters like UV(0), Soft focus and Polarising filters have specific effects. UV filters cut out UV light which can help to cut out Haze in the air. Polarising filters cut down on light that has been reflected (and therefore polarised), this can be from the atmosphere to cut or boost the brightness of the sky or from other surfaces like water and glass.
ignoring wave-partial duality
consider light as a wave oscillating on a plan
the plan of oscillation can be anything from 0 to 360degrees, there will be many-many waves propagating together all on different plans of oscillation, totally random
when light hits a semi-transparent surface at grazing incidence some of the light will be coupled into the media, whereas some will be reflected
the light that is reflected now only has the wave oscillating parallel to the plan, it has become linearly polarised, the rest of the light is coupled into the medium
the same occurs within your camera; light is split according to polarisation
a linear polariser rejects all light EXPECT the plan of interest
if a linear polariser were set crossed to a polarising splitter in your camera no light would hit the sensor in question
in a circular polariser the oscillating wave is set-spinner (can't remember why)
IIRC it goes something like | O - O
with a circular polariser there is always a component of polarisation in the correct linear orientation for the camera sensors to function, albeit with less light available
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the reason a polariser enables one to cut reflections from a surface, the circular polariser rejects the reflection (well most of it, only a linear polariser could reject more, though that would affect the camera as described above)
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does that make any sense?
i'm actually impressed i can remember most if it!!
You need an ND grad if you want to avoid dynamic range issues, no DSLR to date has enough dynamic range to deal with bright sky/dark foreground issues yet . . . best DR on current DSLR's is 6-7 stops, your eyes have 12 stops DR . . . so a grad is required . . . if you try to avoid using one you end up exposing for the highlights and 'bringing up' the shadows which results in noisy images and loss of shadow detail . . . this is because of the non linear way digital sensors record light intensity . . . most of the 'bits' in the pixel are used to represent the lighter tones in the pixel . . .
You cannot capture enough info in many scenes without a grad . . . the sunbeams in this image, for example
Equally you cannot replicate what a circ polariser does in photoflop . . . and not just for removing reflections . . .
Fd
useful info. *joins thread so i remember to read all after work*
You need an ND grad if you want to avoid dynamic range issues
You can just use an HDR software.
<retires to a safe distance>
FWIW, I use a linear polarizer just fine on a DSLR.
for the pedants...
use a circular polariser to allow autofocus to work, with a linear polariser you can only manually focus.
Yeah you can use HDR as long as you carry a tripod and nothing in the image moves, clouds, ripples in the water, trees in the wind, etc, etc, etc . . . simpler to take one image that is correctly exposed in the first place rather than rely on tech that doesn't actually solve the problem in many instances . . . then you have to consider how difficult it is to produce an HDR image that doesn't look like an HDR image . . . I'll carry the wee filter in my pocket . . . 
Fd, brilliant shot.
HDR?
I just did a sick in my mouth.
Nice pics Samuri.
Will be buying ND grad and polarising filters soon.
Yeah you can use HDR as long as you carry a tripod and nothing in the image moves, clouds, ripples in the water, trees in the wind, etc, etc, etc . . . simpler to take one image that is correctly exposed in the first place rather than rely on tech that doesn't actually solve the problem in many instances . . . then you have to consider how difficult it is to produce an HDR image that doesn't look like an HDR image . . . I'll carry the wee filter in my pocket .[quote]
Quite a few misconceptions there. This is an interesting article:
http://www.luminous-landscape.com/essays/hdr-plea.shtml
Taking one correctly exposed image with a ND filter is not as easy as you make it sound
This topic has been closed to new replies.
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