Exposure and using Filters

[GaryMarsh]

As a novice landscape photographer I am aware of the need to use certain filters under certain conditions to capture the correct exposure for subjects containing lots of contrast e.g land/sky or beach/sky. What I am not sure of is how to set the exposure do I have to lock the exposure for the scene before attaching for instance a ND graduated filter or a polarising filter so that the effect of the filter doesn't change my settings or do I set the exposure after attaching these type of filters?
I would appreciate any help on this topic.

Regards
Gary

[JK6065]

Hi Gary,

The answer to this question depends on the type of filter.
Using a circular polarisation filter will reduce the amount of light passing through your lens with two stops, but you van just leave the filter on when metering. Your camera will automatically change the exposure with two stops, because it meters two stops less incoming light.

When using a nd filter it's better to meter before attaching the filter. I use a 10 stops nd filter quite often. Due to the incoming light reduction of 10 stops, the incoming light is too weak for the camera to meter. Therefore you meter the scene you're going to photograph. Dial those settings into the manual mode, attach the filter and dial your exposure up with 10 stops (or opening up your aperture or raise your ISO).

Using a graduated ND filter makes it even more difficult. I've never used one but I would do the following:

I would meter the lightest part of the scene (the part where the dark side of the filter is used), than measure the darkest part. The difference between those two parts (in stops) show you which graduated filter you need to use.
Then I would dial the exposure settings from the darkest part in the manual mode, attach the filter and shoot.

I hope this helps for you. Feel free to ask for anything that isn't clear.

BTW. There are some very good CiC tutorials about filters and metering with filters.

[GaryMarsh]

Hi Jeroen,
Thank you for your help it is much appreciated, I have a better understanding of this subject matter now.

Regards
Gary

[Colin Southern]

Using a circular polarisation filter will reduce the amount of light passing through your lens with two stops

Hi Jeroen,

Just be aware that while traditionally CP's gave a 2 stop attenuation, some of the newer ones are only 1.3.

[JK6065]

Thanks for pointing that out Colin. Though for my CPL's 2 stops is quite adequate. Maybe I'm just using old stuff :-).

@ Gary.

It's easy to find the attenuation for your CPL. Just do two shots in aperture- or shutterspeedpriority or even manual if you wish (one with cpl, and one without) and work out the exposure difference in the exif info.