graduated ND filter

[sgwrx]

i bought a Cokin P holder and a Singh-Ray 3-stop soft transition ND filter.  i have a canon 10D.  i have played with it and gotten typical results, however today was my first shot where i "needed" it.  swampy/forrest scene with bright sky peaking through the tree tops. i shot at f/16, 17-40mm lens and used the depth-of-field preview to find and set the graduated line.  i took several shots in a row with a different location for the filter in each.  the one that looked the best in preview to me, indeed is the best in the series. the foreground is nicely exposed and the trees are nicely exposed but the sky is still blown out.  i'm thinking the trees could have been darker as they reached the top of the frame and of course the sky would have been better not being blown.

should i be looking at a 2-stop hard edge instead? more specifically, is a 2-stop compared to a 3-stop better for quicker transitions?

further, because i'm on a cropped sensor, should i be using a hard edged filter?

EDIT: maybe a larger aperture like f/11 or f/8 would help also?  if so, perhaps i should go to a hard-edge because for landscapes it'd be nice to be able to comfortably use f/16 or f/22 for max. depth of field. although i suppose it depends on the focal length and subject. just a thought?

thanks,

steve

[Tim Gray]

Well, no matter how you position the GND, the transition is still a straight line.  Whether you need a 2 or 3 stop is based on the dynamic range of the scene - regardless of a 2 or 3 stop, you're problem isn't going away. The situation you describe is the primary weakness of a GND, bright sky in the centre, framed by trees (or other objects) on the edge - so you really need a customizable "U" shaped GND - not going to happen.

GNDs have their strengths and weaknesses, but so does the blended exposure technique of dealing with high contrast.  The situation you describe is best handled by bracketing and subsequent processing in PS.  Lots of tools/techniques available for that.

Your sensor size has nothing to do with whether or not the filter should be hard or graduated.

The aperture will affect depth of field and exposure time, but neither of those variables will help you deal with a high dynamic range situation, and I can't see that aperture would have any significant relationship with hard vs graduated.  Don't forget that by f22 diffraction will have started to become a factor, so while the dof gets greater the overall sharpness will start to be impacted.

[sgwrx]

i should have realized that it was ulitmately more than what a GND filter can handle.  it did help, but the brightness of the sky was just too much. i was just fooling around trying the HRD thing, that doesn't give that much of a better result. it looks like i would have needed to come down 2 or 3 stops from my darkest exposure (2sec @ f/16).  a good lesson though!

[Hank]

There's also the possibility of stacking your split NDs to come up with more (in your case 5 stops) effect.  As for positioning the split in the filters, I love usng the smallest size sticky notes.  Position one at the dividing line on the filter, then look through the viewfinder to place the margin in the scene.  By using the smallest size sticky, you can still see the view on either side while the sticky itself is mostly opaque through the finder.  The combo is really handy, and the notes take up very little space or weight in your kit.

[sgwrx]

that's right, i can hold 3 or 4 filters.

There's also the possibility of stacking your split NDs to come up with more (in your case 5 stops) effect.  As for positioning the split in the filters, I love usng the smallest size sticky notes.  Position one at the dividing line on the filter, then look through the viewfinder to place the margin in the scene.  By using the smallest size sticky, you can still see the view on either side while the sticky itself is mostly opaque through the finder.  The combo is really handy, and the notes take up very little space or weight in your kit.
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