Recent content by Bezza

Ok here's a worked example. An object 2cm high is placed 60cm in front of a thin converging lens with a focal length of 20cm. Calculate the position and size of the image. Lens Power (in dioptres), F = 1/f' = 1/0.2 = +5.00D Object Vergence, L = 1/l = 1/-0.6 = -1.67D Image Vergence, L' =...

Ray diagrams are your friend in optics

Please also be aware that the thin lens formula that you have stated is intended for use with the 'real is positive' convention, in which, the symbols are taken at face value and the fact that these reciprocals are related receives no attention. The sign is taken as positive for a real object or...

Cartesian sign convention is as follows: 1. For distances measured along the principal axis (a) the incident light is drawn for convenience traveling from left to right. (b) all distances are measured FROM the vertex of the surface (c) the numerical value of a distance which is measured in...

This formula as i stated previously is a special case of angular magnification when the magnification is at a maximum. It is derived from; M = qL / 1-dL', where q is the least distance of distinct vision, L and L' are the vergences of light entering and leaving the lens respectively and d is...

I'm not saying that you can't do it that way, I'm simply saying that as an optician, that is how i was taught and how every other optician i know was taught. It will only make things harder when you confront more difficult optics problems such as multi lens systems and optical instruments if you...

Also, a quick hint, in optics it is important to follow Cartesian sign convention, in other words take the intersection between the lens and optical axis to be zero, assume light travels left to right, any distances are measured from the lens/optical axis intersection. Therefore the object...

erm not quite...i think you'll find its 1/f = 1/di - 1/do

hrm interesting. When a spectacle magnifier produces an image 25cm in front of the lens you need to use the formula for maximum magnification. The fact that the distance to the cornea has not been specified also suggests this. In other words 5x is the maximum magnification that this lens can...