View Full Version : Fresnel glass?

2-Dec-2011, 15:28
Both my 4x5's have clear glass and Fresnel glass. What does the Fresnel glass do? I read somewhere that the Fresnel could be removed. Why would you remove the Fresnel glass?

2-Dec-2011, 16:27
The Fresnel 'lens' helps to distribute the light hitting the groundglass so that illumination of the ground glass is reasonable even. The Fresnel is a piece of glass, or plastic, engraved (right word?) with carefully spaced concentric rings. These rings act like a lens to bend the incoming light so that the rays are perpindular to the ground glass.

You can see the effect easily. Look at a brightly lit scene with the Fresnel in place, remove it and then look at the GG again, the difference should be readily apparent. Note: If you decide to remove the Fresnel, be sure to reinstall it in it's original position.


2-Dec-2011, 16:35

Perhaps you missed it, but this was the subject of a very informative thread just a few days ago: http://www.largeformatphotography.info/forum/showthread.php?t=83616&highlight=fresnel

3-Dec-2011, 07:28
Thanks that clears it up for me.