Using ND Grad filters

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mah1880

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Mark
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Hi,

I expect this question has already been answered on here many times but I've failed to find the answer using the search function (there are hundreds of threads about filters!)

Hopefully I've got this about right but would like some confirmation... when selecting what ND Grad to use do you meter the sky, then the foreground and how ever many stops difference is the filter you use? e.g. f8, sky shows 1/125 and ground 1/64th therefore a 1 stop ND Grad is the right starting point?:thinking:

I'm currently waiting for some HiTech grads to turn up in the post so can't try anything out to confirm/deny the theory!

Thanks,
Mark
 
Generally I guess. If it's too much, pick a weaker one, if it's not enough, pick a stronger or stack more.

If you want to do it properly you need to decide how bright you want your sky in relation to your foreground. Generally you can allow your highlights to be two stops lighter than your midtone before they blow out so if your midtone (green grass, causican skin or a grey card represent usual midtones) needs 1/100th and your highlights, the brightest points in the sky need 1/1600th then use a 2 stop grad to bring them down to 1/400th. If you want a darker, moody sky perhaps use an extra stop or two. Or perhaps you want a darker foreground, say you expose it at 1/200th instead of 1/100th then you only need a 1 stop grad to bring the sky down to the same level as the first example. The possibilities are nearly endless and there is no 'right' way to do it, so experiment and see what works for you, what effects you like the most. The beauty of digital is that mistakes are cheap :)
 
mah1880 said:
Hi,


Hopefully I've got this about right but would like some confirmation... when selecting what ND Grad to use do you meter the sky, then the foreground and how ever many stops difference is the filter you use? e.g. f8, sky shows 1/125 and ground 1/64th therefore a 1 stop ND Grad is the right starting point?:thinking:
Click to expand...

Yes, that's right.

Remember that its usually in the clouds that most detail is lost, so try using a spot meter if you can.

But I find a 1 stop grad is often enough to retain detail when using a polariser as well.

You can also bracket exposures and choose the most pleasing one.
 
Matt - thanks for the explanation, as usual no easy answer! Some interesting things you've pointed out there which I hadn't thought about so looking forward to getting my hands on my new filters and giving it a go!

Mark
 
If you have a spot meter, meter something you want to be a mid range then set your camera up for that.

then meter the sky. If it is around 2 to 2.5 stops more (which it could be just after sunset) then you don't need an ND grad.

If the sky is any more stops over the mid point than this, then you need a filter which will cut it down to the 2 to 2.5 stops above mid tone figure.

EDIT: Actually, Matt said it better than me.



Steve.
 
I don't have a spot meter but presume it'll be close enough to set the camera to center weighted and zoom in on the right part of the sky/foreground to get a reading?

Thanks!
 
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