
Originally Posted by
Dave Humphries
Hi Izzie,
You don't need to wait for Bill, you can try it yourself (if you can decode my 'instructions'/suggestions) ...
Indoors, in a not too well lit room ...
Put your 12-24mm lens on your camera, set at say 20mm (for a suitable angle of view), set the Camera to Manual exposure, set aperture to f/8
Put your camera on a tripod (I think you have one?) or just on something like a counter top, looking across at an object like a vase of flowers which someone could stand either side of.
Before you fit the filter; focus and get an exposure reading and adjust ISO to achieve longest shutter speed possible, I'll assume this will be say; 0.5 seconds - if you can't get that, stop the lens down some more, and/or close the curtains/blinds, whatever you need to do.
Now set focus to manual to avoid it changing.
Being careful not to upset the framing and focusing, fit your filter set to maximum darkening (I don't what that is, but I'll guess 7 stops)
To compensate for the ND filter, now calculate the shutter speed necessary, 7 stops on top of my guestimate of 0.5 second, so that's; 0.5->1->2->4->8->16->32->64 seconds. Put the camera in B (Bulb) as the shutter speed and start an exposure, walk to the flower vase and stand still for say 25 seconds in one position, then go round the other side and stand still there for 25 seconds, by now the exposure probably needs ending as your 64 seconds will have elapsed, so return to camera and end the exposure. Don't fret over being accurate with my timings.
Good luck (and show us the result if it works), Dave
If you Vari-ND filter maximum is say only 5 stops, adjust accordingly; so aim the metered exposure to be 2 seconds to retain 64 seconds for the test exposure (so you have time to move about).