when was the lens invented

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
when was the lens invented	1.15	0.7	4765	37	26
when	0.2	0.1	9450	4	4
was	1.44	0.6	187	100	3
the	0.92	0.6	1044	76	3
lens	0.67	1	6421	64	4
invented	2	1	6325	22	8

Keyword	CPC	PCC	Volume	Score
when was the lens invented	1.24	0.3	6223	96
who invented bifocal lens	0.25	0.7	7331	44
when was the contact lens invented	0.94	0.9	1219	22
when was the first lens invented	1.38	0.9	5268	96
when was the fresnel lens invented	0.47	0.6	3168	23
when was the zoom lens invented	1.95	0.1	542	27
when was the twin lens reflex camera invented	1.69	0.3	3535	88
when were the first lenses made	1.65	0.7	6410	77
when was lenses discovered	0.52	0.5	7788	19
when were optical lenses invented	1.92	0.8	7039	72
why were lenses invented	0.51	0.3	7892	28
the lens of history	0.69	0.9	4774	51
a history of the photographic lens	1.03	0.7	2968	97
who invented optical lenses	1.13	1	2411	53
history of lenses optics	0.21	0.5	7670	43
who created the camera lens	0.48	0.6	2414	91
history of camera lenses	1.86	0.6	2151	63
who invented lenses for glasses	1.94	0.3	6375	21
what is the history lens	0.13	0.1	6174	56
when was contact lenses invented	0.33	1	1953	9
what are the historical lenses in history	0.46	0.4	9433	54
the year simple glass lenses were introduced	1.79	0.8	1031	100
lens of history definition	1.92	0.9	5427	54
what year were contact lenses invented	0.66	0.3	9148	19
history of prescription lenses	1.38	0.5	1669	63