metering with grad filters

[axl]

Since I have holders and few P series filters from cokin, I'm thinking about getting propper collection of ND gradual and ND filters (so let's say 2, 4, 8 stops from each). I was thinking thoug, how do you meter for them?
Do you have to spot meter sky and foreground and work out the difference between those two to select correct filter?
And one more Q. How is Sigma 10-20 with slim P size fiter holder? I mean does it vignette?
Sorry for all the Qs. But would appreciate helpfull answers...
Many thanx,
BR

[Ed in GA]

Originally Posted by axl

Since I have holders and few P series filters from cokin, I'm thinking about getting propper collection of ND gradual and ND filters (so let's say 2, 4, 8 stops from each). I was thinking thoug, how do you meter for them?
Do you have to spot meter sky and foreground and work out the difference between those two to select correct filter?
And one more Q. How is Sigma 10-20 with slim P size fiter holder? I mean does it vignette?
Sorry for all the Qs. But would appreciate helpfull answers...
Many thanx,
BR

I like to see the answers for this as well.

Ed

[Wheatfield]

Originally Posted by axl

Since I have holders and few P series filters from cokin, I'm thinking about getting proper collection of ND gradual and ND filters (so let's say 2, 4, 8 stops from each). I was thinking though, how do you meter for them?


BR

You are best to use manual exposure and meter the scene prior to mounting the filter. This ensures that the darker values get exposed correctly.

[Nesster]

I've used two methods: 1) meter for the foreground first. 2) put the filter on and let the camera figure out the metering. Often 2) works well enough for me - I can always check the histogram and make adjustments.

[navcom]

Originally Posted by Wheatfield

You are best to use manual exposure and meter the scene prior to mounting the filter. This ensures that the darker values get exposed correctly.

You are correct on the manual exposure mode but I think you got the other part backwards. If you meter before the filter, you will meter for the brightest spot, the very thing you are trying to tone down with a grad filter. The result will be an underexposed picture which is what a ND grad is used to avoid.

Example: You are taking a sunset photo along a beach. If you meter before the filter, you will meter for the bright sun. Then when you put the filter on, you will diminish the brightness of the sun but the beach will still be as dark as it would've been without the filter. The result will be an overall dark picture.

What works best for me is to meter with the filter on and then meter for the area not covered by the grad part of the filter. In the example above, I would meter the beach.

I think I got this right! I'm not a morning person!

[t.mauery]

You could also use bracketing.

Another option is to use auto metering, and then based on the histogram, use exposure compensation.

[Frank Fletcher]

I tend to use 2 methods already described as well as two others depending on the mood and the need.

1) "Just Do It" with the filter and all
2) Manual + GB on foreground w/o filter, then recompose w/ filter
3) Use a mini gray card - w/o filter
4) meter the foreground on aperture priority, then meter the background on aperture priority, then count the stops between them, then apply the filter based on that value. I then use the foreground data to set my final settings.

[Wheatfield]

Originally Posted by navcom

You are correct on the manual exposure mode but I think you got the other part backwards. If you meter before the filter, you will meter for the brightest spot, the very thing you are trying to tone down with a grad filter. The result will be an underexposed picture which is what a ND grad is used to avoid.

Example: You are taking a sunset photo along a beach. If you meter before the filter, you will meter for the bright sun. Then when you put the filter on, you will diminish the brightness of the sun but the beach will still be as dark as it would've been without the filter. The result will be an overall dark picture.

What works best for me is to meter with the filter on and then meter for the area not covered by the grad part of the filter. In the example above, I would meter the beach.

I think I got this right! I'm not a morning person!

You are probably correct. The nice thing about digital is that this is easily tested by the user. My tendency when using an effects filter is to get the exposure correct and then add the filter. Using the method I suggested, I would be metering for the foreground, and then adding a strong enough grad to bring the brighter values down to a usable level.
I suspect that most of the time, sticking the filter in front of the lens and shooting in automatic would work as well as anything else.

[Nesster]

Originally Posted by Wheatfield

I suspect that most of the time, sticking the filter in front of the lens and shooting in automatic would work as well as anything else.

That's been my lazy first cut practice - considering, with the theory of relativity and all, that cutting the sky 2 stops = raising the ground 2 stops. Matrix metering gets me somewheres in between, and then I give it more exposure for the next shot if the ground's too dark still.

[Cideway]

I have used the wide adaptor with the Sigma 10-20 and found vignetting to not be an issue, the only problem that i found was that depending on where the horizon is/was would result on the filter's edge being captured.

That said it works, so long as care is taken, and generally when you are working with a grad filter, you are working slowly, so it wont really matter if you need to take a few test shots.

[creampuff]

When I shoot sunsets, the light is falling fairly quickly so I find shooting in manual mode is waaaay too slow. With my GND attached, I expose using center weighted metering in aperture priority and add positive exposure compensation accordingly. Quick and fast.

[christinelandon]

I usually have good results using the matrix metering on my K10D with the Cokin grad ND already mounted and positioned. On my Spottie, I do my manual "spot metering on a mid-tone" thing, then mount the ND grad and adjust its positioning to bring down the problematic highlight area.

[Mechan1k]

Great thread ... and thanks tot he OP for asking this.
I have been wondering the same thing myself ... and it is good to get some great tips from other experienced users on here.

One reason why i joined this forum ...