# Circular Polarizers VS Photoshop



## Sandyjas (Jun 6, 2014)

Can a good Polarizing filter darken a blue sky more naturally than Photoshop?  Good polarizers are expensive esp. for widest angle lenses.  Also there is always my feeling that by using a filter over the lens you are adding glass, and that (no matter how good the filter) will soften sharpness in the photo.  I don't know whether I should think about using a Polarizer or not for a few shots.  They are expensive.   I would consider using one if they can darken a sky a bit better.  I really don't know.   What arguments Pro & Con are there on this?  Circular Polarizers VS Photoshop.


Thank You So Much for the information. 


Sandy


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## clee01l (Jun 6, 2014)

A Polarizing filter is going to alter the natural color of the sky. So, It won't "darken a blue sky more naturally"   That said, LR gradient filters can produce a more pleasing and interesting blue sky.  But a LR gradient filter can not replace a on lens filter(polarizing or otherwise).  They both have their benefits and shortcomings.


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## Linwood Ferguson (Jun 8, 2014)

The effect on reflections from water and vegetation however cannot be duplicated at all in Photoshop.

It's one of the two filters that seem still to be necessary in the digital age (the other being ND filters).


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## Sandyjas (Jun 9, 2014)

Sorry I was late in thanking you.  I got my neighbor's laptop at her garage sale last summer and after using it for some time it has _something_ on it.  I read Cletus answer Saturday night, but couldn't answer back!  Thank You both for the adjustment information on this.  I can't exactly find this info on the web with my time to look.  Thank you both Cletus and Linwood for the objective knowledge about Circular Polarizers VS Lightroom and Photoshop.  I know more now.   This could be a personal judgment.  So much you can do in editing.  But I was wondering about this.  And also thanks for the tip about ND filters!

Thank You,

Sandy


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## Linwood Ferguson (Jun 10, 2014)

Sandyjas said:


> And also thanks for the tip about ND filters!



Sandy, I should elaborate on the ND filters, as it is different from CPL's.  CPL's do things to the image that you cannot do in post processing, especially with reflections, they make the image different.

ND's do things you CAN do in post processing, but may not be able to do enough of.  An ND filter is (more or less) the same as reducing exposure in post processing, but you can only do that so far.  Let's say you want a slow shutter speed shot of a waterfall (to blur the water).  In bright sun you may be way over-exposed, even at the smallest reasonable F-stop and ISO.  If you are 1 or maybe 2 stops over exposed, you may be able to pull that down in post processing.  If you are grossly over exposed, you cannot -- the detail disappears.   

So an ND let's you use shutter and aperture that you otherwise cannot use (or correct), it does not really affect the (for want of a better word) content of the image, whereas a CPL does.

Incidentally, a CPL also adds a bit of exposure difference (1-2 stops, depending), so you get some ND effect for free there.  Helps around bright sun and water then in both ways.  But some ND filters are 5 or 10 stops, or more interestingly varying stops so part of the image is darkened more than the rest (e.g. for sunsets).


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## Sandyjas (Jun 12, 2014)

Thank You,

I have one ND filter and one Split ND filter.  It would be nice to have 5-10 stops.  I don't use them much, but, you never know when you might need them.  That is also the reason for my question about the CPL.  Would like to have one.  Many rainbows and blank sunny skies where I could use it!  Thank you so much for the information,

Sandy


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## clee01l (Jun 12, 2014)

I have a variable ND filter (ND3-ND400) ND400 is about 9 stops.   I also have a CPL and a series of Cokin Gradient filters.  If I am going to stop down to slur water movement I use the VND.  For sky I use the Gradient filters more often than anything else.   I can handle up to about 4 stops exposure range by shooting RAW and processing with the gradient filter in LR.


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## Sandyjas (Jun 13, 2014)

clee01l said:


> I have a variable ND filter (ND3-ND400) ND400 is about 9 stops.   I also have a CPL and a series of Cokin Gradient filters.  If I am going to stop down to slur water movement I use the VND.  For sky I use the Gradient filters more often than anything else.   I can handle up to about 4 stops exposure range by shooting RAW and processing with the gradient filter in LR.



I never knew there was such a thing (VND)!  This is very cool, saves on all those filters!  I will try my Gradient filter on a sky and process in LR!  I would like a CPL, but also, as more info on the web, I guess if you are not just right with the sun angle, it will not darken the sky, or it can darken only half the sky.  This cuts down on the amount you can use it.  Vegetation enhancement with the CPL, I've seen examples of online, but never in my photos, so I might like that in some instances.  I rarely want to knock out reflections.  Filters were something I was always going to play around with more, but then I took a Photoshop class!

Thank You,

Sandy


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## tanalee (Nov 22, 2014)

I saw a YouTube video recently that suggested using welders glass instead of an ND filter because the glass is so much cheaper. This thread reminds me to try it. I'm guessing it can be bought at a hardware store.


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