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[ANSWERED] Looking for affordable wired cameras for tracking


  • Tech Staff

    @gaspar said:

    Any affordable NDI camera?

     @Fred @Juriaan @fubbi @GertjanB Suggestions?



  • @gaspar

    I would avoid NDI cameras, very CPU heavy, you can see some other topics in the forum about this. I would also avoid USB as it is a pain to extend and has a big delay often -stick with SDI, cheap easy to repair cable that can be 100m long and are everywhere. 

    For tracking you most likely want to have a switchable IR cut filter in case you need to do IR tracking (and get an IR pas if you really want to do IR, this will cut visble light so you can track in front of a projection), changeable lenses and manual control. I would go with an SDI surveillance camera, I have used them a lot for tracking, far from perfect but cheap and they do the job, there are a lot of cheap lenses available and they are easy to work with.

    Here is an example

    https://www.ebay.com/itm/Eyemax-HD-SDI-CCTV-security-Box-camera-1080p-2-megapixel-DUAL-power-XPB-204/161271513301?epid=4025452428&hash=item258c8800d5:g:TOkAAOSwEJlbxhPj

    But search any import supplier like ali express etc for an SDI box camera, and then search the same place for c-monut lenses. You will need an SDI capture card, but just get the cheapest blackmagic capture box that fits your system and has SDI in.

    I have been using these types of cameras for tracking for years, they have their shortfalls but the only other direction I would go is a machine vision camera I also use them but you cannot with Isadora.



  • Hi,


    How far away do you mean when you suggest the distance between the cameras and control might be a long way? Are you talking over 100m?

    I appreciate if you're spending money then you want something you'll be able to use long term and perhaps for other uses where image quality is more of a concern but let's put that aside for a moment.

    Often I find that the key factor with camera setups for live work isn't the 'quality' of the image but speed at which you can process that image and use it. I'd suggest that for tracking purposes really you want the fastest (ie least amount of 'lag') way of capturing the image. 

    Generally the more converting of an image format you have to do the more lag you introduce between 'real time' and the output of your final image. Sometimes with motion tracking this can lead to the tracking feeling sluggish, fast movements of the dancers are more noticeably ahead of the video, or the live sound of speech is distractingly ahead of the video. As such I would try to avoid a set up where the video is being converted between formats multiple times and I'd be nervous about putting NDI in the mix as an extra layer of processing/conversion if you can help it.

    I've always found that the fastest and most reliable way of sending digital video over reasonable distances (up to 100m or sometimes even further) is over SDI. If you can use a camera with an SDI output then great, although these tend to be at the more 'pro' end and therefore expensive. If not, there are cheap reliable and super fast HDMI to SDI converters available. The blackmagic micro converters are a good example but there are others too. As HDMI and SDI are effectively the same format you can move between them with no noticeable delay.

    With digital cameras there's always a slight delay in the image actually leaving the camera and this varies loads between makes and models as well as how you configure the cameras settings. A few years ago I did a test between a couple of cameras we were looking at, both filming a digital clock and going through the same (dual) capture card into a server (it was a hippo in this case rather than Issy but the principle is the same). We output the results side by side and took a photo. The image on the Sony camera's output was well ahead of the one on the Panasonic! There's a picture below I found from the test showing the Panasonic as 60% slower than the Sony. I know that once we'd streamlined the settings on the Sony it got a lot faster than this first test. From memory, changing it to 720p made a big difference, whereas here it's still set at 1080i. In this case we didn't need the extra resolution so opted for speed.

    We use those Sony PMW cameras a lot now because they're really quick compared to similar cameras. Our old PMW200s are great and you still see them in use on a lot of live events with big screens despite being quite an old camera now. The newer versions in that range are just as fast. You can sometimes pick them up for a bit of a bargain second hand on ebay but they still might be out of your range price-wise. You can get some really small SDI cameras like the smaller end of the Marshall CV range, they're more like CCTV cams with interchangeable lenses and I've found them to be really good. You get cheaper ones as well from other brands, I've used some once and they were really good but I'm not sure of the exact model, these might be them.

    So, with digital video I'd suggest going with either:

    Camera with HDMI output --> Blackmagic Micro Converter --> long SDI cable --> SDI capture card --> Isadora

    or

    Camera with SDI output --> long SDI cable --> SDI capture card --> Isadora

    The other option, as you suggest, would be to go analogue. You can get analogue CCTV cameras really cheaply and with good old fashioned composite video you can transfer reliably over pretty long distances with very little drop in quality and basically no delay. The sticky bit is getting an analogue capture card. The last one I used was the Blackmagic Intensity, although I'm sure other users will have other suggestions. Then you could do something like:

    Any CCTV camera --> Long Coax/BNC cable --> Analogue capture card --> Isadora

    The cameras might not be as much use going forward for high quality filming but they might do just the job you need on this on a fraction of the budget of digital cameras. They sometimes have useful infrared filters as well which can be handy for some capture work. Also, given the price, you might be able to use a lot more cameras from different angles if that was something you wanted to explore.



  • @kathmandale thanks for this helpful information ! 

    Best,

    Maxi



  • @kathmandale just to point out that the latency variation has little to do with the camera brand but more the design application. Both Sony and Panasonic make IMAG cameras, designed for live use that will have about a single video line latency from the lens to the SDI out. The series of cameras you seem to be testing with are designed for filming, most often the SDI output module sits after the debayering and encoding for the recording pipeline and is a bit of an afterthought, designed for non-latency critical applications like confidence monitoring. Most of the big camera manufacturers will make some cameras better designed for live use, they often don't have the capacity to record but have very little latency.



  • Hi, I bought one of those camera (usb mpeg fullHD infraRed with zoom and focus). it works smooth, you can add 40m of active usb. Its very cheap.

    I used it to catch ir shadows with ir back light on a rear projection screen with no problem.

    yoyo.





  • @fred

    Thanks Fred. You're right, the old panasonic we were testing there was very much designed for filming and while it was a lovely camera to record with it was painfully slow to use in live work.

    For live work now we use the Sony PMW-200 and on the last show hired some newer Sony PXW-X70. They seem to give a really good mix of speed and the functionality of decent film cameras. On the last show the cameras didn't go through a computer/server but straight to the projector via some ATEM switching. With that setup it was fast enough to look in-sync with live audio. I appreciate they're not going to be within all budget ranges but I'd really highly recommend them.

    Incidentally, you can see that show, Night of the Living Dead: Remix on our website at the moment for free, or pay-what-you-want. I hadn't posted a link on here before as this one wasn't made with Isadora, although we did use Issy in rehearsal quite a lot. Because the show was all set to the timecode of the original film all video, camera switching, lighting, etc ran from a single video and synced up with timecode; once we'd finished making it to operate the show we pressed play then sat back to watch.



  • Hi everyone,


    sorry for the delay in answering.

    So based on all the information I've got from you, I'll probably stick on SDI CCTV with c-mount lenses, although I might have a look at the mini SDI cams @Kathmandale suggested

    Two main questions remain open:
    1. I'll possibly be using IR tracking. I planned to purchase IR LED washers and use an IR pass filter in front of the lense or between lens and sensor. @Fred You talke about a switchable IR cut filter. Does this mean that there are cameras with that include the filter as an option? is there any electronic way of "switching" the filter on or off or is it mechanical, by placing the filter in front of the sensor? I've seen a few CCTV cams that do have "night vision", but there's not much information about how it works, it looks like some of them just push up the ISO.
    So. Any SDI CCTV cam with switchable IR pass lens?  Or can I just buy "any" cam and place the IR pass filter in front of the lens or between lens and sensor?

    2. The second question is reagarding the capture cards. As far as I understand I'll need an SDI to USB3 capture card or an SDI to HDMI converter plus HDMI to USB3 capture card (which are by far more common than SDI-USB3). Will Isadora deal with 2 capture cards? Any reccomendation? @Kathmandale suggested the Blackmagic Intensity  card which allows analogue & HDMI input and in Europe is priced around 180 €.

    I also had a look at @ioio's suggestion but being usb I more inclined to SDI wiring. The camera itself might be cheap, but 40m of active usb cable adds some cost and I'm afraid it is far more sensitive than a sturdy BNC.

    I've found some scond hand Marschall cams, for 300€ each, and might go for them, but the Eyemax HD-SDI CCTV security Box camera suggested by @Fred is far cheaper and new (not sure about any significant differences bewteen brands) or specs between the cameras.

    I'll keep on digging. Thanks a lot to everyone so far.



  • @gaspar

    CCTV cameras have a night mode, this is selectable in a menu and uses a tiny solenoid to move the IR cut filter away (all cameras have an IR cut filter to filter out IR light as the sensor can receive it and it will have various effects on an image for normal light (especially in auto mode where the camera will adjust settings to incoming IR light that we cannot see)). Normally if you want to capture IR light with a normal camera you will have to open the camera and remove this filter.

    To do good IR tracking it is good to have an IR pass filter as well (as well as setting the camera to "night mode" to move away the IR cut filter so IR light can pass), the IR pass filter will block light in the visible spectrum, so only IR light hits the sensor. This makes tracking and using IR lights for tracking a lot easier as you also don't have to deal with any visible lighting you are using. Another benefit is that you can track easily in front of video projection as VP uses visible light (obviously) and tracking software will pick up movements in the video, but with an IR pass filter the camera cannot see the projection, just whatever is lit up with IR light.

    The cameras mentioned by @Kathmandale have better sensors and more control (at a much higher cost) but as they are standard cameras they all have built in IR blocking filters that make them very difficult to work with in IR tracking.

    I use an IR pass filter from midwest optics, there are many choices and you need to match the IR wavelength of your lights and the IR sensitivity of your camera sensor to find the right match and then make sure you get one that covers the size of your lens - they have a simple screw mount system for adding filters to normal lenses.

    https://midopt.com/filters/bandpass/

    Also @Gaspar yes the different brands of cheap security cameras do make a difference, there are a lot but generally they only use one of 3 or 4 sensors and enable some slightly different features in each. Notably the way they handle 3ghz SDI (for 1080p50/60) may or may not comply with the SMPTE spec. Most listings will have a detailed specifications list as well as mentioning the exact sensor (and you can google that to check out the specs like pixel size and it sensitivity.

    Fred



  • Thanks to everyone's help,

    It seems quite hard to find SDI CCTV cameras here in Spain or in Germany (new CCTV standards as HD-CVI or HD-TVI have pushed away SDI, which is now "only" on professional cameras, but no longer on CCTV). In the US and on Aliexpress SDI CCTV cameras are still easy to find.

    Regarding SDI capture cards, there aren't that many. There is the Bla­ck­magic Design UltraS­tudio Mini Recorder for 155 € which has a Thunderbolt2 output (no USB3)

    The other option is getting a SDI to HDMI converter for around 50 € (should have almost no penalty on signal quality or delay) and this way it is possible to use many of the avaliable capture cards feeding incoming HDMI to USB.

    I'll try some stuff with my old camera and an old composite capture card. Later I will probably go for one of the above solutions.



  • @gaspar yes I have only ever been able to order the SDI cctv cameras from China using eBay or AliExpress, but that should not stop you, you order wait and it arrives...as for the capture card if you need USB 3.0 for SDI you can use a magewell card (or again look for one on Ali express there are a lot of cheap copies of the magewell gear there that are actually great). This has been the normal way of getting gear for a long time, I cannot remember the last time I walked into a shop and bought a piece of equipment.


  • Beta Tester

    @kathmandale Night of the Living Dead: Remix, that was a great show!  I saw it at the Liverpool playhouse . I think might have quizzed you on what io you used !😆



  • @n-jones Thank you, that's great to hear. The tour got cut short unfortunately but we loved our week in Liverpool. I do remember chatting about the setup after the show one night so nice to meet you again! Looking forward to next time.



  • @gaspar glad you're getting a good plan together. Let us know how you get on.