B+W UV/IR filters

Ash1978

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Has anyone used the B+W filters to correct that awful magenta cast in dark clothing? I'm going to buy them over the Leica brand, unless anyone has had problems... Thanks for your help!
 
I have both Leica and B & W. They are identical in both appearence and performance - B & W much cheaper however. I leave them permanently on my lenses, and have had no problems. One interesting side effect of these filters which I an not sure if anyone else has mentioned is that when photographing flowers (strong emitters of IR radiation), colours sometimes appear different from what appears natural. For example "blue" bells, which are more purple than blue in real life, become vivid blue using an IR cut filter. It is a very pleasing effect, but not an accurate representation of the scene.
 
I have several B + W filters for my Nikon system and 4 B + W IR filters for my Leica. they work perfectly and they are much less expensive than the Leica filters.

Bat
 
AFAIK the Leica and B+W filters are similar but not identical in pass/cut band characteristics. There is very little to choose between them if they are used on lenses with focal lengths greater than 35mm. It's with wide angle lenses where the differences start to show. The B+W filters when used with focal lengths equal to or less than 35mm can give cyan corners with the M8's in camera corrections.

One reason for the difference is that the pass/cut band of an interference filter shifts depending upon the angle of the incident light. In the corners of a wide angle picture the infra red "cut" moves up into the red end of the spectrum, giving cyan corners. The B+W filters appear to cut into the red more than the Leica ones. You can see this effect if you look through a B+W filter and a Leica filter at the same oblique angle. The B+W filter looks greener. So for wide angles it's best to use Leica filters. The manufactures data sheets only show a filter's characteristics for light entering the filter with normal incidence, they say nothing about when light enters off axis.

There has been some discussion suggesting that the large 67mm Leica filter used on the Wide Angle Tri Elmar (WATE) is slightly different to the other Leica filters. This has been noticed by some people who have used the glass from a 49mm Leica filter mounted in John Milich's WATE adapter.

Bob.
 
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Also, I'm assuming that using the 21mm without the lens sensing on the M8 isn't going to help the cyan cast in the corners -- it is the cut of the filter that makes it the way it is, right?
 
Also, I'm assuming that using the 21mm without the lens sensing on the M8 isn't going to help the cyan cast in the corners -- it is the cut of the filter that makes it the way it is, right?
Correct. In fact if you intend to use an IR cut filter with lenses which aren't coded you will find that a program called Cornerfix is a most useful tool. It will allow you to build profiles for any make of UV/IR cut filter and lens to eliminate cyan corners and if needed will also fix corner vignetting. It's available for Mac or PC.

http://sourceforge.net/project/showfiles.php?group_id=197345

Full documentation is included in the package.

Bob.
 
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