Printable View
I bought a Calumet 7X loupe to help with focusing on the GG. The rear element can be turned one complete circle to lengthen the overall length of the loupe. What is the function of this feature?
I've observed that when the loupe is at its longest length, the image on the GG appears blurry and grainy. When the loupe is at its shortest length, the image on the GG is sharp and grainy. The grains belong to the GG right?
The loupe didn't come with a manual.
The adjustment is for focusing the loupe. Before using the loupe, you focus it on the groundglass grains. Then when you focus the subject, the image of the subject will be at the plane of the groundglass.
Ernest is correct, but the part of the issue that may not be immediately obvious is that the adjustable focus on the loupe allows for clear overlays or screens that might be placed on the back of the ground glass. In contrast, a fixed-focus loupe is designed to work only with standard-thickness GGs, and the use of any sort of overlay or screen behind the GG creates a problem.
Thank you for the quick answers!