neutral density filter - how do they work

mfacer

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hey...

I have tried taking a few "bulb" mode shots with my 20d - usually of water falls etc.... but of course they all just come out white!

I assume I need a Neutral Density filter? Is so, what "x" do I need... there appear to be 2x 4x etc..... I have a 4x for an old camera but never got to use it really.....

how exactly do they work, and what sort of conditions and settings would one typically use it with?

thanks for any info :)
 
a neutral density filter is quite simple, it cuts out light down to a certain amount, basically a x8 will give you 8 more stops to use with your shutter/aperture, which means longer expsures, i assume you want the creamy effect of water which an ND8 will be able to give you but you cvould use something lighter,
There are also graduated ND filters which are usually more useful for most shots,
 
I see.... so if I were to leave the shutter open for 4 seconds, it would effectively be the same as leaving it open for 0.5 seconds? (8x)

Makes sense!
Thanks :)
 
I'll show you:

morze_042.jpg


morze_041.jpg


those two shots were taken with NDx4 filter (f9, 1/10 sec) in the midday/ full sun.
What is more you can brilliantly play with a DOF because it allows you to open the apperture more in the midday. :D
And as you see in the photos above ND filters do not make any difference to colours, so it is worth buying :D
 
thanks for the link ferny :)

I actually knew what ND filters did and everything, but not what the numbers meant and when i went into a shop to find a graduated ND filter the only thing they had was x8 which he told me meant 8 stops (i didnt actually ask he just told me) so i just assumed that was right because i didn't know any better and the shop seemed like a decent photography based shop, its bad now how many shops have people with no idea in them, especially when it makes me screw up and give people wrong advice. sorry!,
 
mfacer said:
I see.... so if I were to leave the shutter open for 4 seconds, it would effectively be the same as leaving it open for 0.5 seconds? (8x)

Makes sense!
Thanks :)

almost, with an 8 stop filter you would leave it open 2 min 8 seconds or 128 seconds.

for that effect however, your meter reading would be something like 1/250 so 8 stops down is

1/125
1/60
1/30
1/15
1/8
1/4
1/2
1

tada, one second shutter speed.
 

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