Polarising Filters

[NigelT]

There seems to be an array of polorizing filters out there and I wondered if there were any differences which may affect digi camera lenses.

I need one for my new Canon 40D.

I called into Jessops in town today and their own filter was £46 and a Hoya version was £50+ !!!!!!!!!!!

I have seen on line filters at around £28 some of which appear to have one side coating?but wondered if this affects the image.

None used that I have before and which i still use seem to be a problem so mis it all just quality levels of glass? Anyone any ideas please?

[crisscross]

If you are shooting RAW (and using one of the more powerful converters, DxO my favourite, but never tried ACR), do you need a physical filter at all? You can apply very similar effects using gradient selections in PP (I use Nikon Capture NX2, but I am sure Photoshop must have similar facility and NX2 works perfectly well on tif output from DxO)

[Dave Humphries]

You can apply very similar effects using gradient selections in PP (I use Nikon Capture NX2, but I am sure Photoshop must have similar facility and NX2 works perfectly well on tif output from DxO)

Only in respect of darkening skies, Chris.

I think Nigel is going to need a real circular polarising filter (CPL) to cut reflections on water, cars, glass, etc. when the need arises.

Cheers,

[Colin Southern]

If you are shooting RAW (and using one of the more powerful converters, DxO my favourite, but never tried ACR), do you need a physical filter at all? You can apply very similar effects using gradient selections in PP

Hi Chris,

A CP is one filter you can't emulate well in PP - in terms of reducing glare from water - foliage - even off the oils in human skin.

[crisscross]

Hi Chris,

A CP is one filter you can't emulate well in PP - in terms of reducing glare from water - foliage - even off the oils in human skin.

The solution for this in NX2 is to use 'Selection control point', which if placed in sky also extends proportionally faded selection to everything picking up the same colour range. This is a develoment of NIK/Nikon 'U-point technology', which in its original form was a bit flaky but is nevertheless patented. The software automated selection can also be added to and subtracted from manually by brush and then it is like a layer to which any enhancement or tool combination can be applied without affecting unselected areas.

Anyone care to give me a URL to a suitable subject for treatment? (RAW & unadulterated, but not from 60MP Hasselblad)

[Colin Southern]

The solution for this in NX2 is to use 'Selection control point',

Hi Chris,

I'm not familiar with NZ2, but I just don't understand how it (or any PP) software could reveal detail that just wasn't captured in the first place (eg remove glare on water so that rocks below can now be seen). I can shoot something for you if you like, but it seems like a wee bit of a waste of time in my mind

[Davey]

It's safe to say no pp can do that since. Even in the case of reflections if the software could accurately analyse and build up a picture of what's beneath the reflections it would be easier and higher success of perfect result if you used a cpl IMO, software is good at doing what hardware cannot and vice versa. Why use software to do something the camera can do naturally and easily, and more importantly better and more accurately.

Reading chris' comment I see he asks "do you need" rather than saying "you don't need", I guess because chances are for some what they want the polar filter for is something that has a software workaround they don't know about (or haven't considered). Obviously for skies (depending on what you are doing) then a filter might not be a must. Even then software, budjet, OS compatability, computer familiarity and time constraints might rule out pp route even if it was the better or equal result.

I don't own a polariser but plan to get one, water in particular is the main subject that makes me think there is no real way around it other than cp. Obviously things like gnd can have digital work arounds in many cases (and no doubt traditional film development stage work around albeit probably more difficult than a filter in that case) and some of the applications of polariser will have a software equiv. However some of the applications of it won't since the only real way around the reflection and related issues is polarising the light being captured.

[shreds]

Chris,

Nikon aka Nik software have now produced a Viveza plug in for PS & LR so you can use U Point technology on these applications which is usually quicker and simpler than layers in PS.

Personally I would agree with the comments that a good polariser is still essential in a lot of situations, and yes it is the quality of the glass that makes these expensive in certain cases with a variety of coatings. They all do the same job but it is like comparing a budget lens with a Pro top of the range one. You get what you pay for and it is the quality of the glass between the subject and sensor that can make a difference.

All depends on your own standards and the prospective use of the resultant pics.

[crisscross]

Hi Chris,

I'm not familiar with NZ2, but I just don't understand how it (or any PP) software could reveal detail that just wasn't captured in the first place (eg remove glare on water so that rocks below can now be seen). I can shoot something for you if you like, but it seems like a wee bit of a waste of time in my mind

Fair point; I had not considered getting through the reflections to within the water. Likewise you keen guys who are evidently keen on real filters will have uses for them I have never dreamt of.

[Colin Southern]

Obviously for skies (depending on what you are doing) then a filter might not be a must.

I've given up on CP filters. In terms of skys, I believe that they can be beneficial with a medium lens, but with anything wide-angle all they seem to do is give uneven skies.

[Dave Humphries]

I've given up on CP filters. In terms of skys, I believe that they can be beneficial with a medium lens, but with anything wide-angle all they seem to do is give uneven skies.

I had another mooch around your website Colin and I have to say; I can't see a single image where a CPL would have benefitted you significantly.
They're just no help for the type of subject and photos you take.

Given the wider angles you work at, you're absolutely right about the skies too.

So I can see why you have given up.

Cheers,

[ajith.rajeswari]

Hi Nigel,
17 Mile Drive
These are some shots taken with Nikon CP filter (18mm Lens).
You have see trees, water, sky to compare with . No much manipulations.

~Ajith

[NigelT]

Hi all

I am used to using polorising filters for film cameras to parrallel before the T90 came along and circular after but have not bought one for a fair while as the ones I had fitted the new lenses.

I use them to take pics thro' water, cut out distracting (or intensify) reflections in glass and to 'blue up' skies and increase detail in clouds. I have used one that I had on the350d and wish to get one for the new lens but as I said am staggered by the differential in prices. There are some at around £10 on the web and others over £50.

I am not flushed with money tho' I have purchased the 40D - out of retirement settlement - but I guess my main concern is with the optical quality of the glass and if there are any aberations that particulary show up thro' digi pics that would not otherwise on film and at what point should I set a minimum cost level or a prefered supplier.

I use Cokin filters also both A and P type for various reasons such as graduated grey filters to reduce light from skies when taking buildings against the light. i find these most useful even on digi cameras as it saves a deal of work after the picture has been taken.

[Tareq Alhemrani]

I don't use CPL at all now since last year, almost 95% of my shots are including the sky, where the CPL can't help me out to get better results in corners, so i don't use it and i am doing great without.

[Colin Southern]

...and i am doing great without.

Even if you do say so yourself

[ckuklbac]

I have found that using a cpl is useful in developing cloud edges in panoramic shots and especially in aerial photos of snow covered mountains (I live in BC). I sometimes use 2 on the same lens at the same time, one cpl and one non-circ as neutral density filters of variable density (just rotate the front filter over the static filter) especially for creating white water trails at waterfalls etc. (I can get exposure times of over 2 seconds in broad daylight using this technique)

[Colin Southern]

Hi Ckuklbac,

Welcome to the CiC forums. I notice that you said you're from "BC" - where's that if you don't mind me asking?

[atvinnys]

snow covered mountains....BC sounds like British Columbia, in Canada...then again just a late guess

[Daniel Salazar]

Hi Nigel and if you check the B+W are even more expensive than £50, everything depend on the quality of the glass and also on the wide.

About emulating a CPL, I'm using Nik's plugins and I can tell you that you can't definitively reveal details as if you ld be using one.

[ckuklbac]

snow covered mountains....BC sounds like British Columbia, in Canada...then again just a late guess

Yep, BC is Western Canada up against the Pacific, sorry for not explaining further. I have posted a couple of shots of the waterfall I mentioned above here:
http://picasaweb.google.com/ckuklbac...32387454218594