Using Filters
- Thread starter mdq8
- Start date
Don Kuykendall_RIP
RIP :(
Your metering should tell you the correct exposure.
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Sent from my iPhone using Tapatalk
I like this video for trying to explain it...
https://www.youtube.com/watch?v=h3TVJ8LzriY
https://www.google.com/search?q=how+to+use+gradiant+filters&ie=utf-8&oe=utf-8#q=how+to+use+gradient+filters
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BackdoorArts
Senior Member
A graduated filter (I'm assuming you're talking ND) will effectively apply exposure compensation to part of the image (i.e. the sky). Nomrally this is done because the sky would otherwise blow out the image if you meter for what's below. In general, if you were to use matrix metering when using this filter you should get a well exposed image since it evaluates the entire frame. But if you're concerned with making sure that a certain part of the frame is well exposed then use spot metering for that area and hope for the best, adjusting the graduated filter value as needed (if possible).
If you use a graduated filter, colored filter, or any filter that isn't completely clear, it will affect your exposure. As the others have mentioned, the camera will compensate and still evaluate the exposure with the filter in place. What will happen, however, is that something will change--either your aperture, shutter speed, or ISO--depending upon which mode you are using (Aperture Priority, Shutter Priority, Manual, or if you have auto-ISO enabled).
Perhaps that's what you meant when you asking about changing the aperture. It is one way for the camera to compensate. For example, if you are in shutter priority, the camera might alter the aperture to correctly expose the image. It all depends upon what settings you are using.
If you use an ND filter that has a hard line (as opposed to a graduated ND filter), then you will want to use a wider aperture. In those instances, if you are using an ND filter with the hard line, it will be visible when shooting stopped down. That would be a time when you'd need to adjust your aperture wider (open it up more).
Perhaps that's what you meant when you asking about changing the aperture. It is one way for the camera to compensate. For example, if you are in shutter priority, the camera might alter the aperture to correctly expose the image. It all depends upon what settings you are using.
If you use an ND filter that has a hard line (as opposed to a graduated ND filter), then you will want to use a wider aperture. In those instances, if you are using an ND filter with the hard line, it will be visible when shooting stopped down. That would be a time when you'd need to adjust your aperture wider (open it up more).
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Fred Kingston
Senior Member
I'll add my 2 cents... Good filters have known values with regard to f-stops. Especially ND filters... I shoot in manual modes only... So I meter the scene, and then add the appropriate exposure compensation by adjusting the aperture or the speed based on the f-stop value of the filter...
Some circumstances, you want to select the speed... so you adjust the speed...an example would be waterfalls... You want sharp depth of field, but you want that creamy wispy water... select a large DOF around f16 and meter the scene using your camera's meter... add the ND filter, and reduce the speed the value of the ND filter... you might have to follow this process for very dark filters because you won't be able to meter/focus correctly with the filter attached...
Polarizers and colored filters, you should be able to attach and meter thru them because they're usually only 1 or 2 stops difference... whereas a lot of dark ND filters can range from 4,6, to 10 stops...
Some circumstances, you want to select the speed... so you adjust the speed...an example would be waterfalls... You want sharp depth of field, but you want that creamy wispy water... select a large DOF around f16 and meter the scene using your camera's meter... add the ND filter, and reduce the speed the value of the ND filter... you might have to follow this process for very dark filters because you won't be able to meter/focus correctly with the filter attached...
Polarizers and colored filters, you should be able to attach and meter thru them because they're usually only 1 or 2 stops difference... whereas a lot of dark ND filters can range from 4,6, to 10 stops...
Fred Kingston
Senior Member
that's why they make a Bracketing mode... 
Dawg Pics
Senior Member
...and the delete button.
I just take some test shots, look at the image and the histogram, make some adjustments and then try again. I then load them into Photoshop and take a closer look.
The ND filter I own is ND8, which will knock down light by 4 stops. Again, you have to put the filter on and take some test shots to see if it is having the effect you want.
I also own some cheap graduated color filters. I just now put the gray one on my camera and set the camera to shutter priority and aimed it at at the brightest part of my computer screen. I moved the focus point to the top of the viewfinder where the dark part of the filter was. When metering, the F stop changed from F16 without the filter to F13 with it. The top focus point couldn't reach the darkest part of the filter so I moved the focus point to the center and held the filter in front of the camera placing the darkest part of the filter over the focus point. The F-stop changed to F8.
You can also see the F-stop change as you rotate the filter around.
In manual mode I centered the meter at F16. After putting the filter on, the meter centered at F11 with the focus point at the darkest part I could place it.
This will at least give you an idea of what the filters are doing if you don't already know. Now I know what my gray graduated filter does on my camera. I didn't know before because it isn't marked with any kind of value. How it affects color and contrast is another experiment.
I just take some test shots, look at the image and the histogram, make some adjustments and then try again. I then load them into Photoshop and take a closer look.
The ND filter I own is ND8, which will knock down light by 4 stops. Again, you have to put the filter on and take some test shots to see if it is having the effect you want.
I also own some cheap graduated color filters. I just now put the gray one on my camera and set the camera to shutter priority and aimed it at at the brightest part of my computer screen. I moved the focus point to the top of the viewfinder where the dark part of the filter was. When metering, the F stop changed from F16 without the filter to F13 with it. The top focus point couldn't reach the darkest part of the filter so I moved the focus point to the center and held the filter in front of the camera placing the darkest part of the filter over the focus point. The F-stop changed to F8.
You can also see the F-stop change as you rotate the filter around.
In manual mode I centered the meter at F16. After putting the filter on, the meter centered at F11 with the focus point at the darkest part I could place it.
This will at least give you an idea of what the filters are doing if you don't already know. Now I know what my gray graduated filter does on my camera. I didn't know before because it isn't marked with any kind of value. How it affects color and contrast is another experiment.
BackdoorArts
Senior Member
Histogram, image review with "Highlight" clipping turned on, and eye balling it.