Quote Originally Posted by SchwinnParamount
... or as I learned, if your camera has a fresnel lens in front of the existing ground glass then you will still have to use that fresnel lens with a new ground glass or you won't be able to get a sharp image on your negative.
If you have a fresnel and decide not to use it, you will have to measure the fresnel thickness and then shim the ground glass that same thickness to maintain the correct focus registration.