Current state of affairs of camera modules - Page 1
Forum section: electronics / projects

author: VooDust
author_rank: Regular Contributor
timestamp: September 09, 2020, 12:07:25 pm
content: HiI've been tinkering with a camera for my project, an ESP32-CAM which has an integrated OV2640 camera module. But I'd like something more elaborate in terms of picture quality (e.g. good low light performance).However, from what I've seen the possibilities available generally fall into these categoriesthe kind of OV modules which are very cheap, but really terrible image qualitya bit more sophisticated modules like the new raspberry pi camera module with interchangable opticshttps://www.raspberrypi.org/products/raspberry-pi-high-quality-camera/but this module only works with the raspberry pievery other camera that is not a "module", i.e. is based on some hard-to-get industry standard with insane data rates for which you have to design controllers and DDR memory and generally way over my level. Also, seem to be available only in quantities of thousands and only to the "industry"Now don't get me wrong, I understand that camera technology is hard. But it just seems strange that while it seems every gadget nowadays comes with a camera included, let alone an abundance of cheap USB webcams, the casual "maker" is left out of a lot of options.My question is, is there some alternative that would fit between type 2) and 3) of this list? My project works like a wildlife cam, making a few snapshots here and there, but I'd like them to be of higher quality.On the other hand, moving the project to a raspberry Pi just because of that one available camera module seems a bit much... I mean my Logitech web cam surely does not run Linux, but I might be mistaken...Other options are just buying the USB cam that meets my ideas and trying to find a driver to use it with the Raspberry Pi via USB, but this seems more like a software challenge than an electronics challenge, if you know what I mean.At this time I'm also considering getting a used action cam, because they're small, and "remote control" it with an MCU, and then try to read the SDcard to "get out" my image.I'm sure I'm facing the same issues than a lot of people before me, so what are your thoughts?

author: MosherIV
author_rank: Super Contributor
timestamp: September 10, 2020, 07:52:10 am
content: I not an expert in this field but when I looked at it 7 years ago for work, it boiled down to the fact that most ccd module manufacturers are only interrested in volume sales which means they are generally only working with device (I mean mobile phone or web cam) manufacturers.That is why you cannot find anyhting on the market for low volume or prototyping.The pi option is not as bad as you think. They have a module version that fits in a simm slot. I think it is called a pi zero.

author: VooDust
author_rank: Regular Contributor
timestamp: September 10, 2020, 08:15:39 am
content: Quote from: MosherIV on September 10, 2020, 07:52:10 amexcept for the price of the camera!Seriously though, I didn't know about the pi zero, thanks. The documentation for the pi camera says "It is compatible with all models of Raspberry Pi computer from Raspberry Pi 1 Model B onwards". Hopefully this includes the pi zero.Other than that, yeah, I think you pointed out the situation quite right. They don't bother "going retail" and/or this is actually much harder than we think to create camera modules, which is reflected in the price point of the Pi camera I guess.

author: magic
author_rank: Super Contributor
timestamp: September 10, 2020, 01:17:39 pm
content: There are some USB camera modules on AliExpress, many with removable M12/s-mount (standard webcam/CCTV lens mount) optics. I suppose these days they all use UVC drivers so any Linux board will run them.The RasPi thing you linked is 1/2.3" sensor so barely larger than the usual stuff.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: September 10, 2020, 01:41:11 pm
content: I suspect part of the issue is also that camera sensors are, inherently, ASICs (99.9% of all consumer-oriented sensors are CMOS - from smartphones to webcams to point-and-shoot to even the highest end pro-photography and cinema cameras costing tens of thousands of euros/dollars).A CMOS image sensor pixel is, essentially, a photo-diode and a buffer, and a few switches to 'clear' the pixel and to connect the buffer output to an ADC.The sensor designer has a choice to make: do we put the analog-to-digital conversion on the same piece of silicon or not? And guess what, in every single sensor I am aware of (except for one**), the answer is 'on the same die'.Then comes the next question: Do we read out the ADCs directly, and digitally process that off-chip, or do we do this too on the same die as the pixels? I believe this is where some more variation is common, with bigger, higher-end sensors in pro cameras have this in the controller ASIC off-chip, but the smaller sensors in phones etc do this on-sensor too.This gives you a lot of advantages: You have to use a lot of silicon area anyways for the sensor, and the digital circuits to do this is tiny, so you don't have to pay a lot 'extra' for this. You decrease your I/O count which is an added advantage. And you have a chip that speaks a standard protocol (usually MIPI for phone-camera type sensors). And one final, huge advantage: any form of pixel calibration, to compensate for dead pixels, more/less sensitive pixels, variation in gain of the buffers over the sensor, can all be calibrated for within the sensor. This is a huge part of the DSP that is done by the high-end DSLRs and so on, and part of why they do the processing of data off-sensor.Keep in mind that the raw sensor data off of one of these sensors is actually quite a lot. a 1Mpix sensor with 8-bit-per-pixel readout, taking one image per second already needs over 8 Mbit/second readout speed. Any faster than that and you can see how the rates quickly shoot up if you go to faster transfer times and more megapixels (and more bits per pixel, I think 10 or 12 raw bits is not all that uncommon even in the lower-end, but I'm not 100% sure, I'm not that much of an image sensor expert).*modern sensors actually have some really interesting complex stuff going on in a pixel to get rid of leakage and lower dark current and deal with diffusion time in silicon being slow etc - really cool stuff.**The one exception I know of is the family of image sensors that was commissioned by Arri in Germany for their Alexa series of pro-cinema cameras. They use off-chip ADCs for god-knows-what-reason.

author: Scrts
author_rank: Frequent Contributor
timestamp: September 10, 2020, 02:01:49 pm
content: Go to the car dealership and buy a rear-view digital camera, however you will need a data deserializer and power circuitry. E.g. this camera would require Power-over-Coax injection and TI DS90UB934 deserializer:https://www.ebay.com/itm/Genuine-GM-2019-1500-2500-3500-TRUCKS-Tailgate-Trailer-Package-CAMERA-Unit/264803407841?hash=item3da78357e1:g:TB0AAOSw6dZfFvyx#viTabs_0It outputs 1280x720 30FPS YUV422 over 8bit interface, BT656.

author: wizard69
author_rank: Super Contributor
timestamp: September 10, 2020, 09:06:19 pm
content: You might want to consider going to a local thrift store and buying an old digital camera with a suitable interface. Adafruit has a large collection of modules:https://www.adafruit.com/category/68.Edmund Optics has some stuff on clearance. Newark has all sorts of image sensors and at least one evaluation module. Basler has a whole bunch of embedded camera modules and D3Engineering has a couple.In the end there is an almost endless supply of various suppliers of sensors and modules.