circular polarizer & vignette

J.T.

I have come across this a couple times when using my circular polarizer for landscape shots.

On certain shots it seems as if maybe the polarizer filter cast some type of shadow or vignette at the four corners of the image. Of course I accidentally deleted the memory card that had the problem files so I have none to show as of now. Is this a polarizer issue? It doesn't happen when I don't use it.

It seems that it occured when I shot around a 1/60th at f/5.6, f/4, f/5 at approx. 18mm. It didn't occur at 1/80th at f/5.6 at 18 mm but occurred again at 1/60th, 1/50th, 1/40th at f/3.5 at 18mm. Finally it happened on 1/160th, 1/125th, 1/100th at f/3.5 at 18 mm.

Any ideas on what is causing this? I haven't spent a lot of time to duplicate but when I tried, I couldn't duplicate the problem.

Thanks.

Scott_Quier

Sounds to me like you are using a tall filter on a short focal length lens and the metal edges (what are those things called anyway) are interrupting the light path.

pathfinder

An 18 mm lens is likely to vignette when using a polarizing filter, unless it is the slim style and even then it will on a full frame camera.

Some shooters do not recommend using polarizers for use with lenses greater than 24 mm full frame as there is too much variation in the sky due to the different angles to the suns axis across the frame.

J.T.

pathfinder wrote:

An 18 mm lens is likely to vignette when using a polarizing filter, unless it is the slim style and even then it will on a full frame camera.

Some shooters do not recommend using polarizers for use with lenses greater than 24 mm full frame as there is too much variation in the sky due to the different angles to the suns axis across the frame.

Thanks to both of you for your responses. I will have to be more aware of that when shooting landscapes.

jfriend

J.T. wrote:

I have come across this a couple times when using my circular polarizer for landscape shots.

On certain shots it seems as if maybe the polarizer filter cast some type of shadow or vignette at the four corners of the image. Of course I accidentally deleted the memory card that had the problem files so I have none to show as of now. Is this a polarizer issue? It doesn't happen when I don't use it.

It seems that it occured when I shot around a 1/60th at f/5.6, f/4, f/5 at approx. 18mm. It didn't occur at 1/80th at f/5.6 at 18 mm but occurred again at 1/60th, 1/50th, 1/40th at f/3.5 at 18mm. Finally it happened on 1/160th, 1/125th, 1/100th at f/3.5 at 18 mm.

Any ideas on what is causing this? I haven't spent a lot of time to duplicate but when I tried, I couldn't duplicate the problem.

Thanks.

You've gotten most of the answer already, but I thought I'd summarize and add a little more. These issues can all contribute to vignetting.

1. The widest angle your zoom will go
2. Using a circular polarizer that isn't specifically designed to be thin with a wide angle lens
3. Shooting at your max aperture for the lens (if you stop down to f/8, the vignetting will likely disappear)
4. Stacking more than one filter (like putting your polarizer on top of a UV filter)

First, make sure there are no other filters on at the same time.

Then, for landscape shots with a polarizer, you should go test your camera at f/8. You may not see vignetting at that aperture (which is generally good for landscapes anyway).

If you still see some vignetting at f/8, then you will need to either back off from the widest your lens can go (perhaps just a few mm of zoom) or get a "thin" polarizer. If you want to shoot wider than f/8, you may also need to do this.

J.T.

jfriend wrote:

You've gotten most of the answer already, but I thought I'd summarize and add a little more. These issues can all contribute to vignetting.

1. The widest angle your zoom will go
2. Using a circular polarizer that isn't specifically designed to be thin with a wide angle lens
3. Shooting at your max aperture for the lens (if you stop down to f/8, the vignetting will likely disappear)
4. Stacking more than one filter (like putting your polarizer on top of a UV filter)

First, make sure there are no other filters on at the same time.

Then, for landscape shots with a polarizer, you should go test your camera at f/8. You may not see vignetting at that aperture (which is generally good for landscapes anyway).

If you still see some vignetting at f/8, then you will need to either back off from the widest your lens can go (perhaps just a few mm of zoom) or get a "thin" polarizer. If you want to shoot wider than f/8, you may also need to do this.

Thanks jfriend,

It's all making more sense and I see exactly why it happened. Thanks!