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View Full Version : Leupold 36X BR/BRD and use with camera filters



ehkempf
03-29-2013, 08:19 AM
Has anyone used their Leupold 36X BR/BRD with camera filters such as a UV, yellow, amber, or orange, etc.? If so what were your thoughts on how it might have improved sight picture, etc.? Also for those of you that have tried it, what size filter did you use to fit the Leupold 36X?

Thanks,

Ed

Boyd Allen
03-29-2013, 05:15 PM
Having played around with holding various camera filters in front of and behind rifle scopes, it seems to me that wearing shooting glasses with colored lenses would offer the same benefit with the added advantage of being able to use them with any scope. One thing to consider is that filters cut down on light, which is at a premium on high powered scopes with smallish objective diameters, like the one that you mentioned. If you use something in a light yellow, it will do a lot for contrast and sharpness on dull overcast days. Amber or orange will act like "blue blocker" sun glasses and sharpen the image by cutting way down on the blue spectrum light, avoiding the circle of confusion that it creates. Generally, polarizing filters are too dark to be useful.

Andy Cross
03-29-2013, 06:59 PM
Having played around with holding various camera filters in front of and behind rifle scopes, it seems to me that wearing shooting glasses with colored lenses would offer the same benefit with the added advantage of being able to use them with any scope. One thing to consider is that filters cut down on light, which is at a premium on high powered scopes with smallish objective diameters, like the one that you mentioned. If you use something in a light yellow, it will do a lot for contrast and sharpness on dull overcast days. Amber or orange will act like "blue blocker" sun glasses and sharpen the image by cutting way down on the blue spectrum light, avoiding the circle of confusion that it creates. Generally, polarizing filters are too dark to be useful.

True filters absorb light. However they do not alter the size of the circle of confusion the optical system produces and therefore do not alter the focus or sharpness. Filters that absorb blue and vilot wavelengths will reduce image flare within the scope and your personal optical system the eye. The lower the flare factor the greater the MTF and your perceived resolution. Unless the ambient light is high in blue vilot wavelengths little benefit is gained. Overcast days don't necessarily mean the light is high in those wavelengths. An extended sunshade is also an effective way to reduce flare. A polarizing filter will only be effective when the light entering the scope is itself polarized. Target paper does not reflect light in a polarized manner.
Andy

Boyd Allen
03-30-2013, 10:37 AM
Andy,
I have used a polarizing filter (circular polarizing) in front of a scope, on a range where the direction of fire is north, and found that as I rotated the filter in its mount that there came a point where the image was different, with improved contrast, but as I said before, the amount that the image was darkened made the trade off seem not worth while.

In photography polarizing filters are used to darken the sky, make it a deeper blue, when using color film (pardon the antique reference) , the effect is most pronounced when the camera is pointed at a right angle to the arc of the sun. The filter must be rotated till the effect is most pronounced, which is why all of the filters that I have seen are constructed so that the filter can be turned while mounted on the front of a lens. These filters are also commonly used to reduce unwanted reflections from glass and metal surfaces. As to my remarks about yellow or orange filtration, I have a pair of prescription glasses that have lenses that were first dyed yellow, and then an orange tint added (plastic lenses) to give a sort of orange gold tint, that is not as irritating on a bright day as straight yellow would be. During the winter, when foggy and or heavily overcast conditions are common, the difference in contrast, apparent sharpness, and depth is quite striking, and of great benefit when driving. I may have the bit about circle of confusion wrong, but as I understand it, because our eyes have a single lens system they cannot compensate for the fact that blue light focuses at a longer distance behind the lens than other wavelengths, and that under certain conditions filtration can improve apparent image sharpness. Although my reference to the mechanism by which this is achieved may have been incorrect, nevertheless, the observed effect is quite real. I am curious, ave you experimented with the filters that I mentioned while viewing a target through a rifle scope as I have?
Boyd

Added later: Speaking of polarized light, the light coming from my LCD monitor must be entirely polarized, because if I rotate a polarizing filter in front of my eye, while looking at the screen, at one point of the filter's rotation, the screen goes entirely black. No, this does not relate to rifle scopes, but I thought that it was interesting.

http://www.ehow.com/info_8335247_tips-shoot-polarizing-filter.html