Grad filter confusion

Mangelwurzel

Mangelwurzel

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I've just bought a Hitech soft GND filter.
It's the 0.9 density which i understand is 3 stops.
It didn't look as dark up one end as i was expecting, which sounds daft i know, but i did a test.
I switched to Tv with a shutter speed of 1/100th and changed to spot metering and took a reading which gave an aperture of f/11.
I then put the dark end fully over the centre of the lens and took a second reading on the same spot and got an aperture reading of f/5.6.

Correct me if i'm wrong but isn't f/11 to f/5.6 2 stops, or am i being a complete berk? :thinking:
 
It would depend a lot on the size of the 'spot' that the camera uses for metering.

Was the 'light' end of the grad over the spot to start with, or fully off?
 
Yes - 0.9 is 3 stops and from 5.6 to 11 is 2 stops. Cannot explain the discrepancy in metering, but did you have the camera tripod mounted (so meter was measuring exactly the same spot), and are you sure the intensity of the light did not change between readings? Either of these might cause the discrepancy.
 
coldpenguin said:
It would depend a lot on the size of the 'spot' that the camera uses for metering.

Was the 'light' end of the grad over the spot to start with, or fully off?
Click to expand...

It was fully off.

bigbigblue said:
did you have the camera tripod mounted (so meter was measuring exactly the same spot), and are you sure the intensity of the light did not change between readings?
Click to expand...

Yes, tripod mounted and pointing at the garden fence. I actually took 3 readings (off, on and off again) and it went f/11, f/5.6 and back to f/11 so i'm sure the light did not change so quickly (not a cloud in the sky at the moment).

I guess it's just not an accurate test. I was just worried that i might have been sent a 2 stop filter (even though it's engraved 0.9) :)
 
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