m8 metering with and w/o IR filters

[dougi]

What are other users experience with metering with and without IR filters?

I find that for warm light (tungsten, halogen) , you lose about 1/2 a stop by slapping a filter on. Which is quite annoying as don't really want to lose that for available light! But then don't want magenta casts either! Sounds like the meter itself is sensative to IR as well.

Was shooting a friends party indoors on the weekend, which required F1.5 on the 50mm Nokton and ISO1250. Couldn't really have done it with 1/2 a stop less light, but there is a lot of magenta to fix!

 

[jaapv]

It is quite logical. By putting up this filter you lose the IR you don't want to hit the sensor. So you lose that part of the exposure. It depends on the amount of IR in the shot, as the filter has a factor 1 for visible light. So in light that is totally devoid of IR the filter will make no difference in exposure, if you want to take a shot with IR light only (for instance with a filtered flash) you will not be able to take the shot at all, as 100% will be blocked.