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Video Camera Lens Fundamentals Carlo Beltrano www.canonbroadcast.com.

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Presentation on theme: "Video Camera Lens Fundamentals Carlo Beltrano www.canonbroadcast.com."— Presentation transcript:

1 Video Camera Lens Fundamentals Carlo Beltrano www.canonbroadcast.com

2 LENS SELECTION CRITERIA What is the application? (studio, field, news, copy stand, etc.) Which camera model? (mount type, CCD size, 16:9/4:3) What VIEWING ANGLE is required? (wide, telephoto) How much of a ZOOM RATIO is required/desired? How will the lens be controlled? (manually, controls, remotely)

3 VIDEO LENS SPEC 20X8 FILM LENS SPEC 8~160mm

4 ANGLE OF VIEW Determined by: Lens Focal Length & CCD size Angle of View = 2tan -1 Image size (CCD or film) Focal Length X 2 Standard Image Sizes 2/3” CCD (4:3):8.8mm X 6.6mm 2/3” CCD (16:9):9.59mm X 5.39mm 1/2” CCD:6.4mm X 4.8mm 35mm Movie:24.92mm X 18.67mm 35mm Still:36mm X 24mm w h

5 Focal Length and Image Size

6 VIDEO LENS NOMENCLATURE J11aX4.5 BIRS J = 2/3” CCD IRS = w/ 2X YH = 1/2” CCD VRS = w/ 0.8X WRS = w/ 2X & 0.8X KRS = none B = compensated for prism 4.5 - 50 mm 9 - 100 mm ( with 2X)

7 F NO = f D The smaller the F NO, the brighter the image

8 F- number vs T-number F NO = T NO = T NO = 3 aperture focal length F NO Transmitance % X 10 example T NO = F 2.8 86% X 10

9 2/3” LENS OUTPUT 11 mm Diameter

10 2/3” CCD (4:3 only) 2/3” CCD (8.8 x 6.6 mm) Lens image 11 mm Diameter

11 2/3” CCD vs 1/2” CCD 2/3” CCD (8.8 x 6.6 mm) Lens image 11 mm Diameter 1/2” CCD (6.4 x 4.8 mm)

12 2/3” CCD (16:9) 16:9 CCD (9.59 x 5.39 mm) Lens image 11 mm Diameter

13 2/3” 16:9 CCD (4:3 mode) 4:3 mode (7.19 x 5.39 mm) Lens image 11 mm Diameter

14 Fixed 4:3 CCD 4:3 CCD (8.8 x 6.6 mm) 11 mm Diameter Lens image 1 12 2 3

15 16:9 CCD Switchable CCD in 16:9 Mode 16:9 mode Lens image 11 mm Diameter 1 12 2 3 (9.59 x 5.39 mm)

16 11 4:3 mode Lens image 11 mm Diameter 22 3 2 2 3 Switchable CCD in 4:3 Mode (7.19mm x 5.39mm)

17 1 1 16:9 / 4:3 lens compensation With 0.82X Lens image reduced by 18.5% (9mm Diameter) 2 2 3 1 1 2 2 3 Lens image 11 mm Diameter 11 Lens image reduced by approx. 20%

18 16:9 / 4:3 SWITCHABLE LENSES J17aX7.7 WRS J11aX4.5 WRS J22aX7.6 WRS

19 16:9 / 4:3 SWITCHABLE LENSES (BOX TYPE)

20 image size is 11mm diameter for both formats HDTV lenses vs. SDTV (NTSC) lenses Red and Blue abber. correction is better on HDTV lenses prism compensation is different between the two tracking error is minimized on HDTV lenses overall resolution is better on HDTV lenses

21 RGB OFFSET (2/3” LENSES) 10 um 5 um NTSC HDTV

22 When an SD lens is used on an HD camera, the MTF is greatly reduced when an image is slightly out of focus. The amount by which an image is out of focus which causes only a 10% MTF loss in SDTV, causes a 50% MTF loss in HDTV. MTF: HD vs SD

23 Depth of Field Depth of field =   x F NO x distance 2 ( focal length 2 ) - (   x F NO x distance )  permissible circle of confusion Behind Object for 2/3” ccd,  = ccd diagonal # of raster lines for SDTV,  = 0.021 mm for HDTV,  = 0.010 mm for 16mm,  ~ 0.009 - 0.012 mm

24 Range Calculator Test Q1 Find the focal length required to satisfy the following conditions: width of stage to be in the frame: 10ft distance between camera and stage: 70ft camera: 2/3” 4:3 ccd

25 Range Calculator Test Q2 How far back (distance) from a stage must a camera be placed in order to satisfy the following conditions: the full stage set height of 40ft must fill the frame (vertically), for maximum depth of field, the widest part of the lens is used: in this case an 8mm focal length, you are using a 2/3” 4:3 ccd camera.

26 Q & A


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