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AG-AF100 28Mm Wide Lens

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AG-AF100 28Mm Wide Lens Contents 1. What change when you use the different imager size camera? 1. What happens? 2. Focal Length 2. Iris (F Stop) 3. Flange Back Adjustment 2. Why Bokeh occurs? 1. F Stop 2. Circle of confusion diameter limit 3. Airy Disc 4. Bokeh by Diffraction 5. 1/3” lens Response (Example) 6. What does In/Out of Focus mean? 7. Depth of Field 8. How to use Bokeh to shoot impressive pictures. 9. Note for AF100 shooting 3. Crop Factor 1. How to use Crop Factor 2. Foal Length and Depth of Field by Imager Size 3. What is the benefit of large sensor? 4. Appendix 1. Size of Imagers 2. Color Separation Filter 3. Sensitivity Comparison 4. ASA Sensitivity 5. Depth of Field Comparison by Imager Size 6. F Stop to get the same Depth of Field 7. Back Focus and Flange Back (Flange Focal Distance) 8. Distance Error by Flange Back Error 9. View Angle Formula 10. Conceptual Schema – Relationship between Iris and Resolution 11. What’s the difference between Video Camera Lens and Still Camera Lens 12. Depth of Field Formula 1.What changes when you use the different imager size camera? 1. Focal Length changes 58mm + + It becomes 35mm Full Frame Standard Lens (CANON, NIKON, LEICA etc.) AG-AF100 28mm Wide Lens 2. Iris (F Stop) changes *distance to object：2m Depth of Field changes *Iris：F4 2m 0m F4 F2 X X <35mm Still Camera> 0.26m 0.2m 0.4m 0.26m 0.2m F4 <4/3 inch> X 0.9m X F2 0.6m 0.4m 0.26m 0.2m Depth of Field 3. Flange Back Adjustment Tolerance Changes 35mm Full Size: Tolerance <0.8mm f = 50mm @F22 -- > 4/3” : Tolerance <0.21mm f = 25mm @F11 Return Adjustment becomes more precise. 1-1.What happens? • If you have 50mm lens of 35mm full size lens (Canon, Nikon and so on.), what happens when you use it with 4/3 . The view of field becomes View of Field 2 times telephoto size. 50mm with 35mm Full Frame 50mm lens 25mm lens (Canon, Nikon and so on) with 4/3” camera with 4/3” camera Depth of Field The depth of field becomes deeper. Iris F5.6 fl. 50mm lens Iris F5.6 fl. 25mm lens Iris F2.8 with 4/3” camera with 35mm Full Frame with 4/3” camera Return 1-2. Focal length • Focal length changes if the imager size changes. • To get the same view angle (Horizontal angel). • If you compare 35mm Full Frame with another lens, – Standard View Angle: 39.6degree (Horizontal) • Wide Standard Tele • View Angle 65.5 ° 39.6° 10.3 ° • 35mm Full Frame: 28mm 50mm 200mm • ANSI Super 35mm: 19mm 35mm 138mm • Normal 35mm: 17mm 31mm 122mm • 4/3” : 14mm 25mm 99mm • 2/3” : 7.5mm 13.3mm 53mm • 1/3” : 4mm 7.2mm 29mm 35mm Full Size Super 35mm 4/3” 25mm 35mm Focal Length 50mm Return 1-3. Iris (F Stop) • If an imager size change, depth of field will change. – If F stop is the same, depth of field will change by a imager size – If you want to keep the same depth of field, you have to change F stop. *distance to object：2m *Iris：F4 ＜Focus area＞ 2m 0m <35mm Still Camera> X 0.4m F22 0.26m 0.2m 3.2m 0.8m <Super 35mm Film> F14 X 0.7m 3.2m 0.4m 0.3m 0.8m <4/3 inch> X 0.9m F11 0.6m 0.4m 3.2m 0.8m <2/3 inch> X 2.0m F5.6 1.6m 0.6m 3.2m 0.8m <1/2 inch> X F4 3.5m 3.2m 3.2m 0.8m 0.8m <1/3 inch> F3 X 7.5m 3.2m 9.2m 0.9m 0.8m Depth of Field Return 1-3-1.Flange Back Adjustment Image Plain 5m Lens Mount 0.1mm 13.2mm 5m 1.3m Flange focal Length 5m 2.8m 25mm 50mm 5m 4.2m Focal Length Distance 5m Flange Back 0.1mm error 50mm : 0.8m error (16%) Return 25mm : 3.2m error (64%) 1-3-2.What happens if Flange Back is not correct? Lens Mount Image Plane Flange Focal (CCD or Film) Distance L f m Δm d 5m M’ = m + Δm • If an object is 5m far from a camera and an error is as follows, – error 0.1mm 0.05mm 0.01mm 0.005mm – Focal length = 100mm : 4.78m 4.9m 5.0m 5.0m – Focal length = 50mm : 4.2m 4.6m 4.9m 4.9m – Focal length = 25mm : 2.8m 3.6m 4.6m 4.8m – Focal length = 13.2mm : 1.3m 2.1m 3.9m 4.4m – Focal length = 7.2mm : 0.48m 0.87m 2.6m 3.4m Distance scale becomes incorrect. Even if you set lens scale to 5m, the actual focus is not 5m. Return 1-3-3.Flange Focal Distance Tolerance Lens Mount Image Plane Flange Focal (CCD or Film) Distance L f m Δm d M’ = m + Δm 1/3” Distance = 5m Iris F5.6 F4 F2.8 F2 F1.6 7.2mm Flange Back Error 0.03mm 0.022mm 0.015mm 0.011mm 0.009mm 2/3” Distance = 5m Iris F11 F8 F5.6 F4 F3.2 13.2mm Flange Back Error 0.11mm 0.08mm 0.056mm 0.04mm 0.032mm 4/3” Distance = 5m Iris F22 F16 F11 F8 F5.6 25mm Flange Back Error 0.41mm 0.30mm 0.21mm 0.15mm 0.11mm 35mmm Full Frame Distance = 5m Iris F44 F31 F22 F16 F11 F5.6 50mm Flange Back Error 1.7mm 1.2mm 0.86mm 0.62mm 0.42mm 0.21mm Size 1/2, then accuracy: 1/4 Return The wider the lens becomes, the more precise the flange back adjustment requires. 2. Why bokeh (Diffraction) occurs? • Fraunhofer Diffraction • d=1.22 λF (Airy Disk Radius) λ : wavelength of light, – F: F Stop (= f/N: N = Effective Diameter) – If the wavelength is the same, bokeh is determined by F Stop only. Airy Disc Return F Stop • F = f/N (f: Focal Length, N: Effective Diameter of Iris) – The bigger F number becomes, the shorter the diameter of iris becomes. – The shorter focal length becomes, the shorter the diameter of iris becomes under the condition of the same F stop Close (Deep) Focal Point Focal Point N: Effective F Stop F4 Diameter IRIS N F4 f =50mm N f =25mm N=12.5mm N=6.25mm IRIS F2.8 F Stop F2.8 N=17.9mm N=8.9mm F Stop: F2 F Stop: F2 f=50mm f=25mm N=25mm N=12.5mm OPEN (Shallow) Return 2-2. the circle of confusion diameter limit • CoC (Circle of Confusion) is d/(1000~1500) where d is the diagonal measure of the original image. • For examples, if CoC = d/1101, the resolution of imager becomes 1080 TV Line (2 x 1101/2.04). Airy Disc Diameter d =6mm 2 x 1.22 Ｆ CoC=0.00545mm 0.0107mm Airy Disc 16:9 Imager F8 F4.1 F4 Airy Disc F2 Diameter F2 CoC 0.00268mm CoC 0.00537mm CoC > Airy Disc Diameter CoC < Airy Disc Diameter You cannot distinguish 2 1101 lines You can distinguish 2 lines. lines. If aspect ratio is 6:9, the height becomes If F Stop becomes bigger, Airy Disc d/2.04. So the vertical resolution becomes bigger. Finally 2d=2.44λF) becomes 1080TV Line. becomes the same as CoC, you cannot distinguish 2 lines。 Return 2-2-2. Comparison by Imager Size • d=2.44 λＦ(Airy Disk Diameter) F16 F4 F11 F2 F2.8 F5.6 F8 0.0215mm 0.00537mm 0.00752mm 0.0107mm 0.0148mm 0.00268mm 0.00376mm F11 F11 F22 F22 F5.6 F5.6 F4 F4 F8 F8 1/3” CoC=0.00545mm 2/3” F16 F16 CoC=0.00999mm 4/3” Return CoC=0.0185mm 2-2-3. Comparison by Imager Size • d=2.44 λＦ(Airy Disk Diameter) F44 F11 F32 F5.6 F8 F16 F22 0.0590mm 0.0148mm 0.0215mm 0.0295mm 0.0429mm 0.00349mm 0.0107mm F44 F44 F32 F32 F32 F32 F22 F22 F22 F22 F32 F32 APS-C ANSI CoC=0.0244mm Super35 CoC=0.0260mm 35mm Full Frame CoC=0.0375mm Return Comparison by TV Format (PAL) • d=2.44 λＦ(Airy Disk Diameter) F4 F11 F16 F2 F2.8 F5.6 F8 5.4μ 7.5μ 10.7μ 14.8μ 21.5μ 2.7μ 3.8μ F5.6F11F8F4 F11F8F4 F22F16F2.8F2 F5.6F16F22F2.8F2 14.810.77.55.4μμ 14.810.77.55.4μμ 2/3” CoC=19μ at PAL Return Comparison by TV Format (720p) • d=2.44 λＦ(Airy Disk Diameter) F4 F11 F16 F2 F2.8 F5.6 F8 5.4μ 7.5μ 10.7μ 14.8μ 21.5μ 2.7μ 3.8μ F8F4 F8F4 F5.6F16F11F2.8F2 F5.6F16F11F2.8F2 10.75.47.5μμ 10.77.55.4μμ 2/3” CoC=15μ at 720p Return Comparison by TV Format (1080i) • d=2.44 λＦ(Airy Disk Diameter) 2/3” F4 F8 F11 F16 F2 F2.8 F5.6 5.4μ 7.5μ 10.7μ 14.8μ 21.5μ 2.7μ 3.8μ F8F4 F8F4 F5.6F11F2.8F2 F5.6F11F2.8F2 10.77.55.4μμμ 10.77.55.4μμμ 2/3” CoC=10 at 1080i Return Comparison by TV Format (1080i) • d=2.44 λＦ(Airy Disk Diameter) 1/3” F4 F8 F11 F16 F2 F2.8 F5.6 5.4μ 7.5μ 10.7μ 14.8μ 21.5μ 2.7μ 3.8μ F4 F4 F5.6F2.8F8F2 F5.6 F2.8F8F2 10.77.55.4μμ 10.7 7.55.4μμ 1/3” CoC=5.5 at 1080i Return Comparison by TV Format (1080i) • d=2.44 λＦ(Airy Disk Diameter) 1/4” F4 F8 F11 F16 F2 F2.8 F5.6 5.4μ 7.5μ 10.7μ 14.8μ 21.5μ 2.7μ 3.8μ F4 F4 F5.6F2.8F2F5.6 F2.8 F2 7.55.4μ 7.55.4μ 1/4” CoC=4.1 at 1080i Comparison by TV Format (1080i) 4/3” • d=2.44 λＦ(Airy Disk Diameter) F11 F32 F44 F5.6 F8 F16 F22 14.8μ 21.5μ 29.5μ 42.9μ 59.0μ 7.5μ 10.7μ F32F22F11 F32F22F11 F16F8F44 F16F44F8 42.929.521.514.8μμ 42.921.514.829.5μμ 4/3” CoC=42μ at 1080i Return 2-3.Airy Disc Calculation In case of F11: – Purple 380–450 nm d=0.005~0.006mm Diameter =0.01~0.012mm – Blue 450–495 nm d=0.006~0.0066mm Diameter =0.012~0.013mm – Green 495–570 nm d=0.0066~0.0076mm Diameter =0.013~0.015mm – Yellow 570–590 nm d=0.0076~0.0079mm Diameter =0.015~0.016mm – Orange 590–620 nm d=0.0079~0.0083mm Diameter =0.016~0.017mm – Red 620–750 nm d=0.0083~0.010mm Diameter =0.017~0.020mm • Use 550nm in the middle of wavelength as the value varies by wavelength.
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