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Hi David
Hope I didnt appear to know what I was talking about, as it happens I think I have misuderstood the article you posted but this is where I was quoting from. please see this below.
magnification of Telescope = objective Focal Length ÷ eyepiece focal length
Example: 600mm focal length telescope (TV-85 telescope) with 10mm eyepiece = 600/10 = 60x. If camera uses 50mm lens, above equation yields 3000mm focal length.
So my 1325mm Focal Length /10mm ep =132X Magnification. I then would multiply this magnification by the camera lens focal length to obtain my effective focal length according to this passage. So if the camera had a 50mm FL my effective FL would be 50 X 132=6600mm
I can see how this might be the case as when taking afocal shots using a digital camera on optical zoom through an eyepiece I can achieve huge magnifications as I am altering the focal length of the camera lens.
I think where i may be going wrong in my comment earlier, is that i am not in fact altering the FL of the camera by simply placing the lens at the end of a 35mm film tube. This is merely a function of focussing on the ep glass from a distance. Perhaps because the prime focus method uses no ep then the value for the non existent ep moves to or close to zero and then Magnification is Telescope FL/zero (or someting close to ) which gives high magnification? Also the FL of these small webcams is likely very small and so have a minimal effect on Telescope FL.
If someone could confirm this to be correct, I will know I'm picking things up ok.
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