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| style="height:20px; width:200px; text-align:center;" |A [[diagram]] showing how to find the [[Focal Length|focal length]] of a '''convex [[lens]]'''.
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*[[Focus]] the [[image]] of a "distant object" onto a [[screen]].
*[[Measure]] the [[distance]] between the [[lens]] and the [[screen]].
: The [[Image Distance|image distance]] (the distance between the [[focus]]sed [[image]] and the [[lens]]) is the same as the [[Focal Length|focal length]] for a "distant object".
: If the [[Object Distance|object distance]] (the distance between an [[object]] and a [[lens]]) is too small, then the [[Focal Length|focal length]] is not the same as the [[Image Distance|image distance]].
===Ray Diagrams===
{| class="wikitable"
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|[[File:ConvexRayDiagram1.png|center|500px]]
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| style="height:20px; width:200px; text-align:center;" |A [[diagram]] showing the [[Ray Diagram|ray diagram]] for a '''convex [[lens]]'''.
In this [[diagram]]:
"Ray 1" is shown crossing the [[Focal Point|focal point]] of the [[lens]] after being [[refract]]ed.
"Ray 2" is shown passing through the centre of the [[lens]].
"Ray 3" is shown crossing the [[Focal Point|focal point]] before the [[lens]].
The [[diagram]] shows that a [[diminish]]ed [[Real Image|real image]] is produced when the [[Object Distance|object distance]] is greater than the [[Focal Length|focal length]] of the '''convex [[lens]]'''.
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{| class="wikitable"
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|[[File:ConvexRayDiagram1.png|center|200px]]
|[[File:ConvexRayDiagram2.png|center|200px]]
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| style="height:20px; width:200px; text-align:center;" colspan = "2" |Comparing these two [[diagram]]s shows that the [[image]] size increases as the [[Object Distance|object distance]] approaches the [[Focal Length|focal length]] of the [[lens]].
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===Magnification===
For further details, see [[magnification]].
The equation for the [[magnification]] of a '''convex [[lens]]''' is:
Magnification = (Image Length)/(Object Length)
<math>Magnification = \frac{L_i}{L_o}</math>
Where:
<math>{L_i}</math> = Length of the [[image]].
<math>{L_o}</math> = Length of the [[object]].