To pass some time I’ve been doing some more tests with my K&F concept ND filters, long exposures, noise reduction, my intervalometer and custom white balance. I was keen to see what happened colour cast and image quality wise when I stacked two of my filters, my ND1000 and my ND8-128 set at ND8 giving a total exposure lengthening of 13 stops (10+3). I first set the custom white balance with my 18% grey card and took one shot at 1/15 sec. @ f/3.5 with single autofocus for reference . I then fitted the filters with the custom white balance selected and took a 9 minute 6 seconds exposure with the camera in bulb mode and with the camera’s noise reduction enabled. As previous both shots were taken under identical lighting and at the same aperture and focal length. Note, one cannot set CWB with a 10 stop or greater ND filter fitted as it’s just too dark thus I left it set with the no filter CWB setting.
I think that the shot with the filters fitted is a tad more saturated but it’s extremely marginal and it’s most definitely worth enabling the noise reduction if it’s not already set to on or auto. The downside is that it more or less doubles the length of the shot as it takes a dark slide so I had to wait nearly 20 minutes to view the resulting image. As an additional experiment I repeated this with noise reduction turned off but the result was pretty poor. Enabling noise reduction doesn’t present me with any issues as, given my interests, I’m unlikely to take many extreme long exposure shots.
Custom white balance and no filter for reference.
Same custom white balance setting with ND1000 and variable ND8-128 set at ND8.