f number

(redirected from F-value)
Also found in: Dictionary, Thesaurus, Encyclopedia.
Related to F-value: P-value

f number

Designation for a photographic lens which gives the ratio of the focal length to the diameter of the effective aperture or entrance pupil. Example: f/8 means that the lens has a focal length eight times the diameter of the entrance pupil. Syn. f/stop; f-value; focal ratio; lens speed. See relative aperture.
Table F1 Sequence of f numbers used in photography with the corresponding relative image brightness and exposure time to maintain constant film exposure. The relative image brightness is equal to the square of the f number fraction
f numberfocal length/pupil exact
f number
diameterrelative image brightnessrelative exposure time
f/0.50.5f/0.5001/0.250.12
f/0.70.7f/0.7071/0.50.25
f/11f/1.0001/10.5
f/1.41.4f/1.4141/21
f/22f/2.0001/42
f/2.82.8f/2.8281/84
f/44f/4.0001/168
f/5.65.6f/5.6571/3216
f/88f/8.0001/6432
f/1111f/11.3141/12864
f/1616f/16.0001/256128
f/2222f/22.6271/512256
f/3232f/32.0001/1024512
References in periodicals archive ?
Constant -25020.26 20742 -1.21 [POL.sub.1] 242.97 127.85 1.90 [POL.sub.2] 33.35 7.31 4.56 [PNC.sub.1] 824.61 313.16 2.63 Adjusted [R.sup.2] 0.89 F-VALUE 28.15 The mixed model
The "lack-of-fit F-value" of 3.27 implies the lack of fit is not significantly relative to the pure error.
The model has an F-value of 23.7 with a P value of about 0.000 implying that the model is significant relative to noise.
The R2 value was 0.39 and F-value (9.89) indicated the overall fitness of the model.
[R.sup.2] 0.5228 0.2857 0.1920 F-value 22.63 *** 8.90 *** 4.13 *** This table presents the estimation results of benchmark model without Z- variables.
Factors DF SS MS = SS/DF F-value P value Regression 3 0.000000 0.000000 98.22 0.074 [[mu].sub.r] 1 0.000000 0.000000 150.48 0.052 [sigma] 1 0.000000 0.000000 1.97 0.394 [rho] 1 0.000000 0.000000 0.56 0.592 Error, E 1 0.000000 0.000000 Total 4 0.000000 DF: degree of freedom, SS: sum of squares, and MS: mean square.
licheniformis CKA1 using Plackett-Burman design Source Sum of df Mean F value P value squares square (Prob > F) Model 18475.00 9 2052.78 28.98 0.0338 X1 833.33 1 833.33 11.76 0.0755 X2 7008.33 1 7008.33 98.94 0.0100 * X3 8.33 1 8.33 0.12 0.7643 X4 3008.33 1 3008.33 42.47 0.0227 * X5 2700.00 1 2700.00 38.12 0.0252 * X6 2700.00 1 2700.00 38.12 0.0252 * X7 1200.00 1 1200.00 16.94 0.0543 X8 8.33 1 8.33 0.12 0.7643 X9 1008.33 1 1008.33 14.24 0.0636 Residual 141.67 2 70.83 Corrected 18616.67 11 total The Model F-value of 28.98 implies the model is significant.
A comparison of the U13 bowling averages of the different racial groups between 2006 and 2012 U13 BA, mean (SD) C/I, mean (SD) 2006 35.9 (37.3) * 31.3 (23.1) 2007 35.4 (28.8) * 18.5 (11.5) * 2008 22.0 (16.8) 31.9 (21.4) 2009 25.7 (23.3) 16.9 (8.3) 2010 22.1 (13.9) 17.5 (9.8) 2011 25.0 (15.0) 24.2 (26.0) 2012 25.6 (18.4) 23.2 (15.9) U13 W, mean (SD) F-value p-value 2006 22.1 (17.1) * 3.6 0.030 * 2007 24.0 (20.3) 4.9 0.009 * 2008 26.3 (24.2) 1.4 0.255 2009 24.4 (18.2) 2.6 0.079 2010 20.5 (15.5) 0.9 0.429 2011 25.5 (18.1) 0.1 0.951 2012 22.0 (15.3) 0.4 0.667 SD = standard deviation.
Source DOF SS MS F-value P-value C (%) A 1 0.8224 0.8224 0.28 0.622 1.30 B 1 50.4078 50.4078 17.44 0.014 79.70 C 1 0.4643 0.4643 0.16 0.709 0.73 Residual Error 4 11.5643 2.8908 -- -- 18.27 Total 7 63.2578 -- -- -- 100.00 DOF = Degree of Freedom, SS = Sum of squares, MS=Mean squares, C=Contribution Table 5 (b): Analysis of Variance for [R.sub.a] 2.
The study used some statistical methods such as correlation, regression analyses and F-value to test the fitness of overall model.
Difference between Age and Health Promoting Lifestyle Indicator Calculated F-Value F-Value Interpretation Health Promoting Lifestyle 2.48 0.052 Not Significant Health responsibility 3.26 0.017 Significant Physical Activity 0.81 0.526 Not Significant Nutrition 1.40 0.243 Not Significant Spiritual Growth 2.11 0.089 Not Significant Interpersonal Relation 3.62 0.010 Significant Stress Management 2.21 0.077 Not Significant Table 15.
From the ANOVA analysis (Table 5), the F-value of the N[H.sub.3]-N removal efficiency was 58.82 while the probability value (Pr) was less than 0.0001.