Filters

[Gogu]

OK it goes like this. I went a few days ago at the local photo store to buy some filters!
I wanted a polarizer and another one to help me get corect exposures on those sunny days, you know when the sky is to bright and you have ot choose - burnt highlights or black everithing else :( ! I asked the people there about this and they said that a degrade gradual grey will do the trick! Well surprise...it doesnt do anithing! I just spend my money on a perfect useless filter! I know that the ND filters are used for this.
Well that filter should i use?

[robertwgross]

I can't imagine using a normal neutral density filter for reducing the brightness of a bright day unless I had some kind of funky manual exposure camera.

However, a graduated neutral density filter makes a certain amount of sense. Commonly, the scene has a dark foreground below and a bright sky background above. You put the (rectangular) graduated neutral density filter in its filter holder on the front of your lens, and then you slide the rectangular piece up or down until the transition of gray versus clear is right on the scene's transition from light to dark. That "holds back" the sky brightness somewhat, and it is a little easier for your camera to capture the brightness and darkness together. That is the good news. The bad news is that it can get a little tricky on where you let your camera meter the scene (with this rig). There is no easy answer. I suggest you let it meter one above the transition and one below, and then take your pick later.

---Bob Gross---

[Gogu]

yea well the filter taht i have is the circular screw in type, not the rectangular one! The problem with it is that it doesnt affect the ligtht at all!Light passes through the higher density gray area above with the same intensity as it does on the normal area! :cry:

[pickledave21]

it seems that lots of people use the same one at the moment but with www.bambooprints.co.uk (http://www.bambooprints.co.uk/) they use the newer models than n the late 90's

with pics of australia usa and fiji. it has beaches, sunsets and very different photographs

[jimsolt]

I can't imagine using a normal neutral density filter for reducing the brightness of a bright day unless I had some kind of funky manual exposure camera.---Bob Gross---
How about if you wanted to use a longer shutter speed and you were already stopped down to the maximum?
JIm

[robertwgross]

How about if you wanted to use a longer shutter speed and you were already stopped down to the maximum?

It seems like I covered this just the other day.

If I need to cut a couple of f-stops of light out, I'll just slap on a circular polarizer, which is something that I always have with me.

---Bob Gross---

[robertwgross]

yea well the filter taht i have is the circular screw in type, not the rectangular one! The problem with it is that it doesnt affect the ligtht at all!Light passes through the higher density gray area above with the same intensity as it does on the normal area!

If you think about this, your comment doesn't make any sense at all.

Of course the gray area filters out more light than the clear area. However, you have to know what your camera is doing with that. For most of the cameras that we are dealing with here, the light metering sensor sees through the lens, which is covered by the gray filter. In some other cameras, the sensor is outside, so it would not "see" the gray filter.

We still don't know whether you are trying to use a neutral density filter or a graduated neutral density filter.

---Bob Gross---

[Gogu]

I have a graduated gray density filter and what i meant is that i see no effect when i look thorugh the viewfinder! The gray part of the filter should darken out the image but is doesnt! MAybe i need a more powerful one?higher density? :rolleyes:

[laatikko]

If the filter has a graduated gray, then it will affect the resulting image. This is easy to test:

1. Put the camera on a tripod (or on a rock, or table or whatever)
2. Take off the filter.
3. Put the camera on Manual-mode, set ISO 100 (or whatever you want), punch in some settings for aperture and shutter. Set the aperture and shutter so that the resulting sky is very, very bright, but not blown out (or how-you-english-speaking-people-say-it, "completely white").
4. Take the first photo.
5. Put on the filter. Make sure that the grey part is correctly over the sky. Don't touch the exposure settings.
6. Take the second photo.
7. Compare these two in a image-viewer.

If you set the aperture and shutter correctly, in the first photo the sky should be very, very pale, and in the second photo the sky should be at least slightly darker. The amount of darkness obviously depends on the density of the filter.

[edit:] If there is no difference, then you either a) did something wrong or b) just found a way to get around laws of physics. If b), then please forward your findings to CMOS-engineers, maybe we will get 100Mpix noisefree sensors someday.

[mbze430]

Maybe you don't know how to use a ND filter or a graduated ND filter. Here is simple instructions.

Set your camera to manual, set an apeture, than meter off your scene, to set the shutter speed. Leave all the settings. Put on your ND filter, and do not change the settings.

The above will darken your scene by the density of the ND.

If you use the automatic modes, the metering system will compensate for the lost of light, and give you the same exact effect as not having a ND filter, just with wider apeture or longer shutter speed. Usually most people use it this way to get longer shutter speed for water movement.

If you do want to use the automatic modes, like P, AV, TV. You need to know how many stop your ND filter has, and than subtract that from your EC (Exposure compensation). So if you bought 1 stop ND, you need to subtract 1 stop from your scene in the automatic mode while the ND filter is on.

[Jon]

There are a couple of articles on using graduated ND filters here, at Singh-Ray's web site (http://www.singh-ray.com/grndgrads.html). If you're using a grad and want to see where it falls, you need to stop down to working aperture. If you're using a uniform ND, it'll affect the whole scene uniformly.