Hi I have an old "loupe" type magnifier here but it has nothing written on it which would give me an idea as to its magnification. Can anyone suggest a way for me to 'estimate' how many x (times magnification) it is? thanks

1. Estimate the focal length by seeing how far from a piece of paper the glass of the loupe has to be to focus a distant scene such as a tree some tens of meters away. 2. Magnification = 1 + (250mm/focal length)

If your friends have loupes of different magnifications, compare yours to theirs. There are not that many variations. 4x, 6x, 8x, 10x, etc.

Hi I assume you want focal length in mm ... so focal length in is ~45mm plugging this in would be: 1 + (250 / 45) = 6.5 ok ... thanks

Hi I wish I had any friends that were into traditional photography. Here in Finland people are digital or not into it. (lets see if that starts anything ... :confused

Sorry. Should have said so, but you got it right so no harm done. FWIW, the 250 mm is a figure for the closest focus of a mythical average person's eyes. If you can focus closer that that, the magnification - for you - increases proportionally. FWIW (2) this definition assumes that your eye is close to the loupe. If you back off and and use the loupe like a reading magnifier you lose the one from the formula - i.e. your lens would be a 5.5x magnifier. Struan