Image Circle, Shading
When viewing the inclined chart from directly above [Figure 1-1 (a)]
A lens has the ability to support a certain sensor size to image. The maximum sensor area that the lens can support it defined as Image Circle.If the sensor size is too large,it causes " Shading " or " Vignetting " .
Normal Macro Lenses
Telecentric Lenses
Camera
Image circle 2/3"
Image circle
Lens
2/3" sensor
Rays
FOV
A non-telecentric macro lens with non-telecentric optics provides depth perception when viewed from directly above on an inclined chart, while telecentric optics allows the chart to be perceived as straight.
2/3" sensor
Vignetting or shading
View of connector pins from directly above [Figure 1-1 (b)]
Normal Macro Lenses
Telecentric Lenses
Camera
Sensor is usually rectangle and only part will be imaged.
If you use larger sensor than the image circle of lens.
Lens
Vignetting or shading on the monitor
Rays
You can see the inside of the pin
Only pin vertices are visible
When the connector pins are viewed from directly above, the sides of the pins at both ends of the screen can be seen by the macro lens of non-telecentric optics, whereas with telecentric optics, the image is viewed completely from directly above, making it easier to detect pin collapses, etc.
Camera Mount
❷ Macro Lenses These lenses are optically designed for imaging in close proximity (distance to the object WD is around 100mm). For example, some of them are capable of capturing objects of a few mm order at high zoom ratios. Our macro lens is designed to be in focus under constant WD conditions, and its magnification allows distortion-free image with high resolution. The focus is only within a certain WD range, so it is necessary to mount it properly. It is smaller than a telecentric lens and is widely used for inspection of electronic boards. We offer fixed magnification, fixed aperture to variable magnification, variable aperture megapixel compatible products. ❸ Fixed Focal Length Lenses Originally developed for surveillance purposes, the WD was designed to work up to infinity. Most of them have an adjustable aperture and focus, making it easy to change brightness and adjust focus. Due to its low price, it is used frequently. However, when used in close proximity, they are unsuitable for dimensional measurements due to significant corner distortions. We have a lineup of products with improved performance in the macro range. ❹ Line Scan Lenses Mainly used for line scan cameras. Most line scan cameras require a light-receiving dimension of about 35 to 80 mm, and recent high-pixel compatible models require a light-receiving dimension of about 80 mm. In many cases, lenses for normal 2D cameras (area sensor cameras) cannot be used.Since this lens has a large light-receiving area, it can also be used for two-dimensional cameras, and stable resolution can be obtained by using light rays with small aberration at the center of the lens.However, since the lens itself is large and heavy, it is not suitable for mounting on moving parts, and the lens mount method varies from manufacturer to manufacturer, making it necessary to confirm and select the camera mount to be used. ❹ Objective Lenses A measuring microscope with an interchangeable objective lens attached. It supports a FOV of several mm to several tens of microns and can obtain high resolution images.It maintains the high-resolution performance of the objective lens and allows for simple image capture into the camera.However, the distance to the object (WD) is short and heavy. We offer a lineup of coaxial-illuminated optical tubes and interchangeable objective lenses that are shaped for easy installation by the user.
Each camera mount has a different size thread and flange back (FB: distance from sensor to lens flange) Common camera mount FB are shown below.
Figure 1-2 Camera Mount
Mount thread
Line Camera FB (mm) F-mount
Area Camera FB (mm) C-mount
Sensor position
17.526 12.526
46.5 * 1 * 1
M42-mount M72-mount
CS-mount M-mount S-mount
M15.5/P0.5 M10.5/P0.5
Mechanical back
Flange back
*1. FB size depends on the camera manufacturer. You need to make sure both mount thread and FB are correct to get the correct image.
VST mainly offers C, F and M72 mount but also some special mounts for remote head cameras. Please contact us for more details if you have a special lens mount.
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