Scotopic Vision

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The CogNet Library : References Collection

The Visual Neurosciences : Table of Contents: Scotopic Vision : Section 1

Conversion tables

To compare psychophysics with electrophysiological experiments and to interpret the findings in terms of underlying anatomical structures and physiological mechanisms, it is useful to have convenient means of converting back and forth between photometric quantities and such things as the density of retinal illumination, or the rate of quantal absorptions within the receptors. Tables 53.1 and 53.2 provide such information. These tables and the rationale for the entries have been published previously (Makous, 1997), but they are reproduced here for readers' convenience and to correct errors in the original.

**Table 53.1 : Rod conversions.**
	Troland	cd m⁻², 2 mm p.	cd m⁻², d mm p.	q str s⁻¹ on ret.	q deg s⁻¹ on ret.	q mm⁻² s⁻¹ on ret.	q µm⁻² s⁻¹ on ret.	q s⁻¹ Rod, Abs.	q s⁻¹ Rod, Act.	mac. Td	Cat Td
1 Troland =	1	0.318	1.273 d⁻²	8.99E+8	2.74E+5	3.23E+6	3.230	6.460	4.310	0.588	0.600
1 cd m⁻², 2-mm p. =	3.142	1	0.250 d²	2.82E+9	8.60E+5	1.01E+7	10.147	20.295	13.540	1.848	1.885
1 cd m⁻², d-mm p. =	0.785 d²	4 d⁻²	1	1.14E+9 d²	3.49E+5 d²	4.11E+6 d²	4.11 d²	8.22 d²	5.49 d²	0.749 d²	0.76 d²
1 q str⁻¹ s⁻¹ =	1.11E−9	3.54E−10	8.77E−10 d⁻²	1	3.05E−4	3.59E−3	3.59E−9	7.19E−9	4.79E−9	6.54E−10	6.67E−10
1 q deg⁻² s⁻¹ =	3.65E−6	1.16E−6	2.87E−06 d⁻²	3.28E+3	1	1.18E+1	1.18E−5	2.36E−5	1.57E−5	2.15E−6	2.19E−6
1 q mm⁻² s⁻¹ =	3.10E−7	9.85E−8	2.43E−07 d⁻²	2.78E+2	8.48E−2	1	1.00E−6	2.00E−6	1.33E−6	1.82E−7	1.86E−7
1 q µm⁻² s⁻¹ =	0.310	0.099	0.243 d⁻²	2.78E+8	8.48E+4	1.00E+6	1	2.000	1.334	0.182	0.186
1 q s⁻¹/rod abs. =	0.155	0.049	0.188 d⁻²	1.39E+8	4.24E+4	5.00E+5	0.500	1	0.667	0.091	0.093
1 q s⁻¹/rod, act. =	0.232	0.074	0.182 d⁻²	2.09E+8	6.35E+4	7.49E+5	0.749	1.499	1	0.136	0.139
1 mac. Td =	1.700	0.541	1.335 d⁻²	1.53E+9	4.66E+5	5.49E+6	5.491	10.982	7.327	1	1.020
1 cat Td =	1.667	0.531	1.308 d⁻²	1.50E+9	4.56E+5	5.38E+6	5.383	10.767	7.183	0.980	1

**Table 53.2 : Cone conversions.**
	Troland	cd m⁻², 2 mm Pupil	cd m⁻², d mm Pupil	q str⁻¹ s⁻¹ on Retina	q deg s⁻¹ on Retina	q mm⁻² s⁻¹ on Retina	q µm⁻² s⁻¹ on Retina	q s⁻¹ Cone Abs.	q s⁻¹ Cone, Act.	Mac. Td	Cat Td
1 Troland =	1	0.318	1.273 d⁻²	2.62E+9	7.98E+5	9.41E+6	9.410	16.610	11.080	0.588	0.600
1 cd m⁻², 2 mm p. =	3.142	1	0.250 d²	8.23E+9	2.51E+6	2.96E+7	29.562	52.182	34.809	1.848	1.885
1 cd m⁻², d mm p. =	0.785 d²	4 d⁻²	1	3.33E+9 d	1.02E6 d	1.20E+7 d	11.98 d	18.81 d²	12.55 dd²	0.749 dd²	0.76 dd²
1 q str⁻¹ s⁻¹ =	3.82E−10	1.22E−10	3.00E−10 d⁻²	1	3.05E−4	3.59E−3	3.59E−9	6.34E−9	4.23E−9	2.25E−10	2.29E−10
1 q deg⁻² s⁻¹ =	1.25E−6	3.99E−7	9.84E−07 d⁻²	3.28E+3	1	1.18E+1	1.18E−5	2.08E−5	1.39E−5	7.37E−7	7.52E−7
1 q mm⁻² s⁻¹ =	1.06E−7	3.38E−8	8.43E−08 d⁻²	2.78E+2	8.48E−2	1	1.00E−6	1.77E−6	1.18E−6	6.25E−8	6.38E−8
1 q mm⁻² s⁻¹ =	0.106	0.034	0.083 d⁻²	2.78E+8	8.48E+4	1.00E+6	1	1.765	1.177	0.063	0.064
1 q s⁻¹/cone, abs. =	0.060	0.019	0.053 d⁻²	1.58E+8	4.80E+4	5.67E+5	0.567	1	0.667	0.035	0.036
1 q s⁻¹/cone, act. =	0.090	0.029	0.080 d⁻²	2.36E+8	7.20E+4	8.49E+5	0.849	1.499	1	0.053	0.054
1 mac. Td =	1.700	0.541	1.335 d⁻²	4.45E+9	1.36E+6	1.60E+7	15.997	28.237	18.836	1	1.020
1 cat Td =	1.667	0.531	1.308 d⁻²	4.36E+9	1.33E+6	1.57E+7	15.683	27.683	18.467	0.980	1