I recently discovered on taobao
that Benro now also sells filters - specifically also 10-stop ND filters. Since ND1000 filters can help give some interesting effects, I decided to purchase first a 77m and a 82mm filter.
I bought the "SD" (Super Digital) filters
. Inspired by Bryan Carnathan's article about 10-stop filters
I decided to do a quick test of the filters. As I had previously purchased a 3-stop Tiffen 82m filter (82ND9
) I decided to test that also for reference.
Since I don't have an "official" reference color plate, I searched around and downloaded and printed this target: http://photojoes.org/colorchecker.jpg
on a laser printer and taped it to a door. Since the printing and my two Osram table lamps used for illumination are likely to give a color cast, so I used the gray boxes to adjust the color temperature for each picture.
(I should say that I'm very much still learning about color temperatures, so I could have done the adjustments incorrectly. If so, please let me know and I'll be happy to update/correct things.)
I chose a deep DOF (f/8) to ensure that I wasn't getting hurt by creases in the paper and non-planarity issues from the taping. Also, since I'm not sure of the lamp filament type, I shot at 0.5sec exposure so reduce or avoid any flicker issues. The 0.5sec, f/8, ISO 100 gave standard exposure with the two lamps.
I'm showing 5 shots, all adjusted to the same (theoretical) in-camera exposure. They have been run through DPP for color temperature adjustment and rescaling to 1200 x 800 px, nothing else.
The camera (5D3) was (obviously) mounted on a tripod (concrete floor), live view was used for initial focus and the lens was then switched to MF. IS was off. Silent shutter and a remote (wireless) trigger was used.
All shots taken at f/8, ISO 100.
1) Control shot, 24-70/2.8L Mk II @ 70mm, 0.5
2) Tiffen ND0.9, 24-70/2.8L Mk II @ 70mm, 4
3) Benro ND10, 24-70/2.8L Mk II @ 70mm, 480
4) Control shot, 70-200/2.8L II @ 200 mm, 0.5
5) Benro ND10, 70-200/2.8L II @ 200 mm, 480
So what are my conclusions so far?
Like Bryan, I find that the Tiffen gives a really bad color cast and much reduced contract. Sharpness seems OK, though. Cost is USD136, according to their website
The Benro filters look quite good with colors very close to the control picture (after correction) and little or no sharpness lost. I'm quite happy with what I see here, especially with the price paid: RMB485-600 (USD88-96) .
Comments, suggestions and improvements/corrections to methodology / design of test are welcome.