I have a Hoya 9-stop ND filter that I've used on occasion. This weekend I was using it during some strong morning daylight. I typical compose the shot, check the settings for shutter speed and aperture while on Av, dial them into M, put the filter on, and then count off some combination of 27 clicks between shutter speed, aperture, and ISO to come up with 9-stops. This weekend it was consistently overexposing by two stops. When I clicked back 6 clicks (recall everything is in 1/3rd increments on a Canon), I'd get a good exposure.
What gives? Bad filter? Bad quality? To be expected?
Well, that's pretty interesting... I'd re-check it with a constant light source shining on a neutral surface. Stick your camera on a tripod and meter without the filter. If it reads 1/100s, the with the filter on it should read about 5 seconds at 9 stops down. Lather, rinse, repeat, varying the light a little, and see if your observation holds.
I'm going to have to try checking my B+W 10-stop and 6-stop to see what they give me.
OK, so I did the test. I used an LCD monitor displaying a large square of white as my illumination. Metered at 1/200 @ f/2.8, ISO 100. Installed each of my 3 ND filters in succession. Results:
Hoya ND8 (3-stop) checks out at -3.0 stops
B+W 106 (6 stops) checks out at -5.4 stops (hmmm...)
B+W 110 (10 stops) checks out at -10.0 stops
I've been inspired by this community to join the ND crowd. Just bought a B+W 110E ~ 10 stop 77mm ND filter (€95). Will try it out later today.
Had no clue of ND's, but I've been thinking often: I need some sort of dark filter for the strong sun that comes in at a low angle here.
Do you folks tend to remove your UV or just add the ND to the stack? Or go crazy and put it under the UV...
Thanks for the inspiration DPC'rs :)
I've been inspired by this community to join the ND crowd. Just bought a B+W 110E ~ 10 stop 77mm ND filter (€95). Will try it out later today.
Had no clue of ND's, but I've been thinking often: I need some sort of dark filter for the strong sun that comes in at a low angle here.
Do you folks tend to remove your UV or just add the ND to the stack? Or go crazy and put it under the UV...
Thanks for the inspiration DPC'rs :)
Congrats, you'll have some real fun with that... take the UV off and mount the ND in its place. Keep the air-to-glass interfaces to a minimum. With a 10-stop filter, it's best to focus and then install the filter, or focus by distance when that's appropriate, or focus by trial/error. Live view might well help, but of course we don't have that option ;-)
You will be able to achieve multi-second exposures in daylight with this filter. The creative possibilities are endless!
