| Electronics > Projects, Designs, and Technical Stuff |
| 1-4cm focal usb camera |
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| VeryFastSnail:
Hello everyone, I’m currently am working on one project that requires close focusing camera, perfectly focus distance would be 1-4cm. This cam will take static pics, and quality is not that important. Pics will be converted to black and white. Picture size could be small, but cam has to be cheap, perfectly under 10$$$ What I already tried to do: * Looked at webcams that are comonly available with little to no success, focal lenght is common at <15cm * Use laptop webcams, same problem as above * Looked on aliexpress for camera modules, found some, ordered, will test soon. focus distance is unknown btw * Thought of adding some kind of lens to decrease it’s focal lenght, maybe someone is better at optics then I’m and could help me with type of lens to use * There are those endoscopic cameras, focal lenght is 3-8cm, but I dont want to dissasemble it... What do you think is the best solution? |
| Siwastaja:
Just move the existing lens further away from the chip to focus closer. |
| magic:
Focal length is not the same as focusing distance. Focal length is property of the lens and it cannot be changed (except for zoom lenses). Focus distance depends on focal length and the distance between the lens and the image sensor, per well known formula: 1/f = 1/x + 1/y. You can focus arbitrarily close by moving the lens further from the sensors. For a webcam, disassembly of the case may be required. This will not be a problem in those AliExpress modules, you can unscrew the lens as far as you want until it falls out. If the distance still isn't enough, extension rings for webcam/CCTV lenses are available. This lens system is known as "M21 mount" or "S-Mount". The lens will be operated outside its intended conditions and image quality may suffer. For serious macro operation (object distance < sensor distance) you may get improved results by inverting the lens (front to the sensor, back to the object). Another possibility is diopter adapters / lens stacking: attach an additional lens to the front of the fixed one. Either a simple high diopter magnifying glass or an inverted webcam lens. |
| DaJMasta:
Look for a USB microscope instead. Generally they will specify their focus distance, but they'll be optimized for up close, and if you get something with a Barlow lens or with a long working distance specified, they'll be able to focus from farther back (not just within a couple of CM), and generally they have lower magnification. Because of the way the optics work, a regular USB camera that can focus very close is already magnifying (unless your output screen is the size of your field of view), so relatively low magnifications will just look like an up-close camera put on a bigger screen, whereas higher resolutions will look more of what you're expecting from an actual microscope. In any case, cheap decent quality (at least for stills) USB microscopes can be had fairly inexpensively. |
| VeryFastSnail:
Thank you for all your answers they are very informative. I will look into it. |
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