Printable View
I have a B&W 0.6 Graduated ND filter (2 stops) that I use for landscape in conjunction with the EF 17-40mm f/4 lens and 40D. I find it very difficult from the veiwfinder to determine the orientation of the filter without looking at the filter on the lens. I can see a difference in the image output with and without the filter (when comparing the same composition with same shutter & aperture). Is this normal or maybe just my eyesight?
It's been a few weeks, so maybe you've already solved your issue, but for what it's worth, here's my experience with GNDs:
I use the Hitechs with a Cokin holder; I have a 0.6 and a 1.2, both Soft Transition filters. The 0.6 is much more difficult to orient through the VF. I use it on the 17-40 as well, and while it appears fairly obvious, with the soft transition I'm not always sure of the placement in the holder. If I had it to do all over again I wouldn't buy the 0.6; I find it's almost never enough. Last week in Big Sur I used both filters together (the holder accepts up to 3 filters) quite often and got good results.
One thing that's helped me is Live View. Though I've used the GNDs hand held, more often than not I'm on a tripod shooting a landscape/cityscape. Activating Live View and then adjusting the GND's position helps tremendously; the transition becomes obvious.
The other thing you can try is the DOF Preview button on your 40D. I shoot with the 40D also, and sometimes that little button can be a godsend. It shows a more accurate view of the final image, using the taking aperture as opposed to the metering/focusing aperture.
I hope you're having more success already, but if not, try the suggestions above and maybe they'll help.
Happy shooting!