ND - Graduated neutral density filters - which one to get?

[Bazinga]

Hi,

Sky and relevant highlights would not be burned out in a digital image correctly exposed to the right. That essentially means that shadows will get less exposure, which in turn may increase noise.

Here is a method to selective darken sky: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/46-fixing-sky-with-luminosity-mask

Here is a image taming pretty high contrast:

Default image: http://echophoto.smugmug.com/Other/Demos/13965719_7UrQm#1196458231_4G2JV-X3-LB
Adjusted in LR: http://echophoto.smugmug.com/Other/Demos/13965719_7UrQm#1196458145_qy3yr-X3-LB

Perhaps not the greatest example, the image could take another +0.5 - +1 stops of exposure.

Best regards
Erik

From what I can see here - you are doing a sort of HDR processing. Also, in your image sky is not at all overexposed. So it's quite easy to give it extra details. However since your digital sensor's exposure range is about 1 1/3 stops you will simply not have enough detail to do anything in post processing short of resorting to proper HDR (multiple bracketed exposures and then using software to combine tones).

GND filters are the only way (at least I haven't seen any other technique) to get images exposed within sensors range. Lee, from what I know, are of a top quality and not extremely expensive.

[Bazinga]

From what I can see here - you are doing a sort of HDR processing. Also, in your image sky is not at all overexposed. So it's quite easy to give it extra details. If there is high dynamic range in the picture you will simply not have enough detail to do anything in post processing short of resorting to proper HDR (multiple bracketed exposures and then using software to combine tones).

GND filters are the only way (at least I haven't seen any other technique) to get images exposed within sensors range. Lee, from what I know, are of a top quality and not extremely expensive.

[BarbaraArmstrong]

Am I the only one using a screw-on GND filter (from B+H) and loving it?  It is in place most of the time, balances sky with the rest of the shot.  Sometimes I turn it around when the water portion of a scene is lighter than the upper area.  I mark the darkest part of the ring on the filter with a dot of nail polish so it is easy to position on the camera.  Once you enjoy the benefits of a nicely saturated sky with fewer or no blown highlights (before you get into post-processing) you will want a GND for each lens you often use for landscape.  Obviously there's the question of which strength to use, but anything is better than nothing when faced with bright skies. --Barbara

[BarbaraArmstrong]

Well, there I go saying B+H when I should have said B+W.  BHPhotoVideo in New York on-the-brain.  --Barbara

[ErikKaffehr]

Hi,

I don't know what you mean with 1 1/3 stops of sensor range.

You are correct that the sky is not overexposed, the trick is to make it darker without getting a dull image.

There are a couple of problems with graduated filters.

1) The cheap ones, like Cokin reduce sharpness (at least in my experience)

2) In many cases we don't have a straight horizon

3) I couldn't use Cokin filters with any of my real wide angles because of vignetting

So what I say is that if the image is correctly exposed for highlights the same effect as with graduated filters can be achieved conveniently in Lightroom or ACR.

If the horizon is non regular the technique I described can be used, or an even simpler variant.

1) Duplicate image
2) Press alt+cmd+5 to used sky as luminosity mask
3) Click to top layer
4) Select multiply
5) Add layer mask

Probably there is some need to paint out some parts of the luminosity mask.

Best regards
Erik

From what I can see here - you are doing a sort of HDR processing. Also, in your image sky is not at all overexposed. So it's quite easy to give it extra details. However since your digital sensor's exposure range is about 1 1/3 stops you will simply not have enough detail to do anything in post processing short of resorting to proper HDR (multiple bracketed exposures and then using software to combine tones).

GND filters are the only way (at least I haven't seen any other technique) to get images exposed within sensors range. Lee, from what I know, are of a top quality and not extremely expensive.

[Bazinga]

Hi,

I don't know what you mean with 1 1/3 stops of sensor range.

Sorry, I should have said 'exposure latitude'. And for digital sensors in cameras, from what I know, it's about 1 1/3 stops. You can extrapolate that to 2, but not really any further. So with higher dynamic range in your composition you will either start losing details in the dark or overexpose the light areas thus losing details there.

You are correct that the sky is not overexposed, the trick is to make it darker without getting a dull image.

There are a couple of problems with graduated filters.

1) The cheap ones, like Cokin reduce sharpness (at least in my experience)

2) In many cases we don't have a straight horizon

3) I couldn't use Cokin filters with any of my real wide angles because of vignetting

So what I say is that if the image is correctly exposed for highlights the same effect as with graduated filters can be achieved conveniently in Lightroom or ACR.

If the horizon is non regular the technique I described can be used, or an even simpler variant.

1) Duplicate image
2) Press alt+cmd+5 to used sky as luminosity mask
3) Click to top layer
4) Select multiply
5) Add layer mask

Probably there is some need to paint out some parts of the luminosity mask.

Best regards
Erik

Thanks for the details on the process of adding a graduated filter in post processing. It definitely works when your shot is within what your sensor is capable of capturing in terms of exposure in a single frame.