Optimum Combination of Camera and Lens. Carl Zeiss AG, Udo Schellenbach, PH-V

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2 Trivialities Not so trivial Experts knowledge

3 What is often the rank of optics at machine vision?

4 Trivialities: What is your sensor size? Does the lens image circle cover the sensor? Which mount does your camera feature? Can we get a stable connection? What is the flange focal distance? Is there any adapter that can bridge the flange focal distance?

5 Optimales Zusammenspiel von Kamera und Optik Not so trivial: What is the bandwidth you work with? (white light, monochrome, NIR) How sensitive is your sensor against incidence angles? How sensitive is your sensor, resp. which aperture do you really need? Which resolution do you want to gain in your object? What is the disired pixel size in your object? What shall be the field of view (FoV)?

6 Expert knowledge: Are you working in the ideal focus distance? Does you lens feature a floating design? How is the tolerance of your sensor specified? How sensitve does the lens react? Are there peridodic structures that can be resolved by the sensor? Are there colored periodic structures that are resolved differently by a Bayer filter?

7 Trivialities: What is your sensor size? Does the lens image circle cover the sensor?

8 Trivialities: What is your sensor size? Does the lens image circle cover the sensor? If the sensor is much smaller than the lens image circle you get usually the advantage that the lens performance in the center is better! u is the image height! The diagonal spread of the sensor should be less than 2 x u

9 Trivialities Which mount does your camera feature? Can we get a stable connection? What is the flange focal distance? Is there any adapter that can bridge the flange focal distance? Typical flange focal distances: F-Mount: 46,5 mm EF-Mount: 44,5 mm M42x1 Mount: 45,5 mm C-Mount: 17,53 mm Works: F-Mount to C-Mount Works: F-Mount to EF-Mount Works not: F-Mount to EF-Mount

10 Not so trivial: What is the bandwidth you work with? (white light, monochrome, NIR) The transmission can be adapted during the design to suit a certain bandwidth. The use of different coatings enhance the transmission at one part of the spectrum but reduces at a nother part.

11 Not so trivial: What is the bandwidth you work with? (white light, monochrome, NIR) MTF at white light MTF at monochrome: 556 nm MTF at monochrome: 800 nm

12 Not so trivial: How sensitive is your sensor against incidence angles? Biogon 2/35: Max. Chief Ray Angle 31, can cause false colors in corners of fullframe sensors. Good for Sensors 4/3. Fullframe depends on sensor behaviour. Quelle: Loxia 2/35: Max. Chief Ray Angle 16, no limitations for fullframe sensors. 43 mm image circle (24 x 36 mm)

13 Nicht mehr ganz so trivial: How sensitive is your sensor, resp. which aperture do you really need? A Fstop of 1,4 gives 400% more light for the sensor against Fstop 4,0. But this is usually paid by less contrast at open aperture. If you need best contrast at wide open aperture you will need to pay high prices for high end lenses. Milvus 1.4/85 bei 4,0 Milvus 1.4/85 bei 1,4

14 Not so trivial: Which resolution do you want to gain in your object? What is the desired pixel size in your object? What shall be the field of view (FoV)? 2 LP/mm 80 LP/mm

15 Not so trivial: Which resolution do you want to gain in your object? What is the desired pixel size in your object? What shall be the field of view (FoV)? Example: Desired (Pixel) Resolution in the object: 20 µm The camera has a pixel pitch of 3 µm The needed ß is 1:7 ß =.. Desired FoV: 140 x 100 mm (172 diag.) The used sensor has a diagonal spread of 16 mm The needed ß is 1:10 ß =..

16 Not so trivial: Which resolution do you want to gain in your object? What is the desired pixel size in your object? What shall be the field of view (FoV)? Now either the FoV needs to be reduced or the sensor size increased, e.g. a full frame sensor (24x36) In our case we decide to increase the sensor size and now we are able to image the FoV of 140 x 100 mm with a resolution of 20 µm.

17 Not so trivial: Which resolution do you want to gain in your object? What is the desired pixel size in your object? What shall be the field of view (FoV)? Desired Working distance (g): 250 mm The necessary focal length is in our case 28 mm! = (1+ß) ß Using a pixel size of 3 µm and a full frame sensor means we need a 71 Mpixel sensor. This sensor is very sensitive and reveals all lens weaknesses. Especially wide angle lenses loose performance towards the edges. We can either accept the performance drop at the edges or extend the working distance and get the chance to use a lens that works better at the edges. E.g the Apo Distagon 1.4/55.

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19 Not so trivial: Which resolution do you want to gain in your object? What is the desired pixel size in your object? What shall be the field of view (FoV)? Diagonal spread in the object: 81 mm

20 Simple Planar 1.4/50 with 16 Mpixel sensor High sophisticated Apo Sonnar 1.4/55 with 16 Mpixel sensor

21 Simple 1.4/50 with 71 Mpixel sensor High sophisticated Apo Sonnar 1.4/55 with 71 Mpixel sensor

22 Simple Planar 1.4/50 with 16 Mpixel sensor High sophistated Apo Sonnar 1.4/55 with 16 Mpixel sensor Simple Planar 1.4/50 with 71 Mpixel sensor High sophisticated Apo Sonnar 1.4/55 with 71 Mpixel Sensor

23 Optimales Zusammenspiel von Kamera und Optik

24 Expert knowledge Are there peridodic structures that can be resolved by the sensor? Are there colored periodic structures that are resolved differently by a Bayer filter? The pixel pitch of green pixels especially in diagonal direction is much smaller than those of the blue and red pixels. Therefore it is much more likely that blue or red moirés appear in case of periodic colored structures.

25 CMYK offset print Magenta, Gelb, Cyan, Key

26 Imaged with scale 1:2 to Bayersensor Frequency = 0.15 x Nyquist

27 Imaged with scale 1:5 to Bayersensor Frequency = 0.4 x Nyquist

28 Imaged with scale 1:8 to Bayersensor Frequency = 0.6 x Nyquist

29 Expert knowledge:a Are you working in the ideal focus distance? Does you lens feature a floating design? Infinity Close Focus (without floating design)

30 Simple focusing: The cmplete lens system is moved back and forth Floating Design: The complete lens system is moved back and forth while parallely the rear lens group moves independantly too.

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