Using ND grad filters

I've got a ND grad filter kit, while I do know the basics on how to use it, I just don't get what is two or one stop ND Grad

RichSoansPhotos wrote in post #17550905
I've got a ND grad filter kit, while I do know the basics on how to use it, I just don't get what is two or one stop ND Grad

Its the density of the shaded bit.

It's the amount of light reduced by the ND grad.

RichSoansPhotos wrote in post #17550905
I've got a ND grad filter kit, while I do know the basics on how to use it, I just don't get what is two or one stop ND Grad

Heya,

1 stop = 1 stop. Just like 1 stop of aperture, or 1 stop of ISO or 1 stop of shutter speed.

If you throw a 2 stop ND filter on, you're stopping 2 stops of light.

The graduated ND filters have one side that is not stopping anything, and a gradual ND side that goes from 0 to whatever value stopping power it's rated for. This is traditionally used for sky shots or anything where a portion of the frame is a lot brighter than the foreground and you want to blend them together in a single shot.

ND filters are commonly useful for using higher apertures in bright sunlight, useful for doing very long exposures (we're talking 30 seconds and longer, into minutes) in bright light, or for the purpose of achieving very long exposure (again, like 2~8 minutes type long). They're also very useful for doing flash/strobe photography with high aperture and a static, slow shutter. Also commonly used for video.

Very best,

The amount of light gathered/captured whilst taking a photo is know as its exposure.
So the camera settings for shutter speed and aperture are adjusted so that the correct amount of light falls on the sensor and so correctly exposes the scene. The ISO can also be changed in digital camera which also affects the exposure by adjusting the "sensitivity" of the sensor electronics (technophiles will probably jump in there and point out everything that is technically wrong with that statement!).

If you allow TWICE as much light to fall on the sensor in a single exposure, you have increase the exposure by 1 stop.
So going from 1/250 sec shutter speed to 1/125 sec will change the exposure by 1 stop.
Going from an aperture of f8 to f5.6 (bigger "hole") will also change the exposure by 1 stop
(note: many cameras have the option of increasing/decreasing the shutter speed and aperture in increments of 1/2 or 1/3 of a stop)

Now suppose you are taking a photo of a scene that requires exposure settings of f5.6, 1/250th sec and ISO of 400
If you now add a "one stop ND filter to the lens" it will restrict the light falling on the sensor by one stop. You will now need to increase the amount of light by double in order to expose the scene correctly. So you could:
a) increase the aperture to f4 leave the shutter speed at 1/250th and leave the ISO at 400
b) leave the aperture at f5.6, slow the shutter speed to 1/125th sec and leave the ISO at 400
c) leave the aperture at f5.6, keep shutter speed at 1/250th but change the ISO to 800
each of these changes would result in double the amount of light hitting the sensor to compensate for the one stop filter for decreasing the amount of light hitting the sensor - thus the exposure remains acceptable.

So why would some-one use a ND filter?

Scenario 1: You want to get that blur effect in water flowing over rocks ... but the light is so bright that even with the aperture of f16 and ISO of 200 your aperture has to be 1/60th sec for a correctly exposed scene. Not slow enough to create the blur you are looking for. So you add a "one stop" filter which allows you to change the shutter speed down to 1/30th sec.
Not enough blur? Change the filter to a two stop filter - now you can slow the original 1/60th shutter speed down by two stops ... or 1/15th.
By adding ND filters with varying amounts of darkening (stops) you can eventually achieve the shutter speed you need to get that blur effect

Scenario 2: You want to shoot a landscape with a sky and land. The sky is reflecting a LOT more light to your camera than the land. If you set your exposure based on the sky, the sky will be exposed correctly but the land will be under exposed - it will look dark and lose detail. On the other hand if you set the exposure for the land, then that part of the scene will be correctly exposed but the sky will be over exposed - it will look white/bright and lose detail.
The solution is to use a GRADUATED ND filter. It will have a darkened area at the top that gradually lightens to a clear section at the bottom. If the difference in exposure between the land only setting and the sky only setting is 2 stops of light (ie the sky is 4 times brighter) than you would grab your 2-stop Graduated ND filter and place in front of the lens (usually in a frame/filter holder) and position the graduation of the dark to light to align with the horizon (land/sky change). So now when you expose for the land, the graduated ND filter will limit the light coming from the sky to 2-stops less. This will mean the sky is exposed correctly and you will retain the detail in the sky.

Look here for additional info about "stop" settings: http://www.photography​mad.com …f-exposure-in-photography

MalVeauX wrote in post #17551599
Heya,

1 stop = 1 stop. Just like 1 stop of aperture, or 1 stop of ISO or 1 stop of shutter speed.

If you throw a 2 stop ND filter on, you're stopping 2 stops of light.

The graduated ND filters have one side that is not stopping anything, and a gradual ND side that goes from 0 to whatever value stopping power it's rated for. This is traditionally used for sky shots or anything where a portion of the frame is a lot brighter than the foreground and you want to blend them together in a single shot.

ND filters are commonly useful for using higher apertures in bright sunlight, useful for doing very long exposures (we're talking 30 seconds and longer, into minutes) in bright light, or for the purpose of achieving very long exposure (again, like 2~8 minutes type long). They're also very useful for doing flash/strobe photography with high aperture and a static, slow shutter. Also commonly used for video.

Very best,

I gathered that

It seems that I ordered a Gradual Grey Medium, Gradual Grey Light and a Gradual Grey Soft filters, other than what it says on the package
This is what I got http://www.amazon.co.u​k …oh_aui_detailpa​ge_o01_s00

Those are 1, 2 and 3 stop filters.

DGStinner wrote in post #17555309
Those are 1, 2 and 3 stop filters.

lol, which one is 1, 2 and 3 stop filters?

RichSoansPhotos wrote in post #17555324
lol, which one is 1, 2 and 3 stop filters?

Light = 1
Medium = 2
Soft = 3

The Amazon link you provided says they're ND2, ND4 and ND8 filters.
The following Wikipedia link breaks down different filter ratings.
https://en.wikipedia.o​rg …_filter#ND_filt​er_ratings

Thanks

The "S", by the way, isn't for "Soft"; it's for "Strong". "Soft" refers to the nature of the transition between ND and clear - "Soft" is gradual; "Hard" is abrupt.