Missed focus
If this occurs it is usually because you have left your camera on autofocus.
Solutions:
- Have your camera on manual focus or set up your camera to use ‘back button’ focus such that depressing the shutter is not involved with focus at all.
- Focus correctly before you place your ND filters on. The camera will have a much easier time finding focus points with a live view without ND filters on.
Light leak
This occurs if there are gaps in the filter holder setup which allow light to reflect off the surface of ND filters. This is a problem for denser ND filters.
Solutions:
- Ensure that your ND filter is inserted with foam gaskets fitting snugly in the holder.
- If your filter holder is prone to light leak, ensure that you cover up your whole setup with a dark cloth.
- If you are using an optical viewfinder, cover it up! This can be done with a piece of Bul Tack, or using the viewfinder cover on a camera strap (for canon users).
Incorrect exposure
It is important that you calculate the correct exposure in changing light. You may only get one chance during ideal conditions on any given shoot! If your exposure time is too short, the image will be too dark with problematic shadow recovery. If your exposure time is too long, the image may have unrecoverable highlights.
Solution:
- Achieve correct exposure and to a test shot without the ND filter on.
- After inserting the ND filter, use an app to appropriately calculate the exposure duration needed based on the strength of the ND filter. Anticipate lengthening this calculated exposure a little when the light is fading (eg. after sunset), or shortening the exposure if the light is improving (eg. Leading up to sunrise).
Are These the Best Filters Money Can Buy?
by Dylan Toh
