Hoya NDX400
Nikon D7000 with Hoya NDX400 (9 stops claimed)
70-200mm f/2.8 VRII
ISO 100
Manual Exposure, +1 Compensation for Metered Exposure
f/16 @ 1.5 seconds
"Fine Weather" White Balance Setting
Shot in brilliant mid-day sunlight.
Loss of eight stops of light, compared to a clear UV filter. Hoya claims nine stops and, given the slight underexposure of this example as compared to the original shot without a filter, I would agree that if I bumped this one up another stop to 3 seconds, it may have matched my original shot a bit better. I regret not having the motivation at this time to dig up histograms for proper comparisons because I think it would be pretty useful for a more accurate comparison. All the same, this told me what I really wanted to know: "Roughly how many stops of light does the Hoya NDX400 ("ND 400") knock down?" and "How bad is the color shift with the Hoya NDX400?" My personal opinion: 8-9 stops and no where near the reported extremes of shift toward magenta I was reading about (to my amateur eyes, that is). Pretty happy with the results of this expensive but capable filter. Clarity looks satisfactory to me, too. I really look forward to putting it to use on some waterfalls or making moving objects (ie: humans) disappear in busy areas.
While researching this filter, I learned that an ND8 is only good for three stops (stretching a 1/250th second exposure to a 1/30th second exposure at the same f-stop and ISO).
Lastly, if anyone ever invents a quick-release mechanism for these filters, I would be all over it. They need to be removed for proper focusing, even in bright daylight. These "black glass" filters are not as dark as an infrared filter, but they are dark enough to really make the auto focus suffer!
Hoya NDX400
Nikon D7000 with Hoya NDX400 (9 stops claimed)
70-200mm f/2.8 VRII
ISO 100
Manual Exposure, +1 Compensation for Metered Exposure
f/16 @ 1.5 seconds
"Fine Weather" White Balance Setting
Shot in brilliant mid-day sunlight.
Loss of eight stops of light, compared to a clear UV filter. Hoya claims nine stops and, given the slight underexposure of this example as compared to the original shot without a filter, I would agree that if I bumped this one up another stop to 3 seconds, it may have matched my original shot a bit better. I regret not having the motivation at this time to dig up histograms for proper comparisons because I think it would be pretty useful for a more accurate comparison. All the same, this told me what I really wanted to know: "Roughly how many stops of light does the Hoya NDX400 ("ND 400") knock down?" and "How bad is the color shift with the Hoya NDX400?" My personal opinion: 8-9 stops and no where near the reported extremes of shift toward magenta I was reading about (to my amateur eyes, that is). Pretty happy with the results of this expensive but capable filter. Clarity looks satisfactory to me, too. I really look forward to putting it to use on some waterfalls or making moving objects (ie: humans) disappear in busy areas.
While researching this filter, I learned that an ND8 is only good for three stops (stretching a 1/250th second exposure to a 1/30th second exposure at the same f-stop and ISO).
Lastly, if anyone ever invents a quick-release mechanism for these filters, I would be all over it. They need to be removed for proper focusing, even in bright daylight. These "black glass" filters are not as dark as an infrared filter, but they are dark enough to really make the auto focus suffer!