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#2
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C5 Fare Dodgers - question
tim... wrote:
"Roland Perry" wrote in message ... In message , at 20:37:27 on Wed, 23 Oct 2019, Recliner remarked: Roland Perry wrote: In message , at 19:05:11 on Wed, 23 Oct 2019, remarked: On Wed, 23 Oct 2019 09:34:49 +0100 Roland Perry wrote: In message , at 07:41:34 on Wed, 23 Oct 2019, remarked: I wonder if dashcams storing low/uncompressed video is so it can accurately capture very fast movement - eg just before an accident - which most video compression systems are not particularly good at. I think it's because they don't want to have the silicon|dollars|power budget of compressing the video. They externalise it to users having to buy stupidly big SD cards. My previous dashcam gobbled through 1.2GB for each ten minute file. There must be more to it than that. Even cheap smartphones can do realtime video compression. They produce files in MP4 format, but not very much compressed. My phone produces typically 150MB per minute (1920 x 1080 pixels). So, Full HD video. Like my dashcam (I presume the camera is essentially the same as that in a phone). The hardware is probably commodity by now. My whole dashcam only cost about £30. That doesn't leave much budget for the lens. The lens is quite large (1.5cm), and wide angle (170 degrees). And yes, it's probably one of the more expensive components. I don't see why non focusing, non zoom-able lenses cost pennies to make It's still a high precision optical component, probably with four or five elements, at least one of which is probably glass. Would it also have aperture blades? |
#3
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C5 Fare Dodgers - question
"Recliner" wrote in message ... tim... wrote: "Roland Perry" wrote in message ... In message , at 20:37:27 on Wed, 23 Oct 2019, Recliner remarked: Roland Perry wrote: In message , at 19:05:11 on Wed, 23 Oct 2019, remarked: On Wed, 23 Oct 2019 09:34:49 +0100 Roland Perry wrote: In message , at 07:41:34 on Wed, 23 Oct 2019, remarked: I wonder if dashcams storing low/uncompressed video is so it can accurately capture very fast movement - eg just before an accident - which most video compression systems are not particularly good at. I think it's because they don't want to have the silicon|dollars|power budget of compressing the video. They externalise it to users having to buy stupidly big SD cards. My previous dashcam gobbled through 1.2GB for each ten minute file. There must be more to it than that. Even cheap smartphones can do realtime video compression. They produce files in MP4 format, but not very much compressed. My phone produces typically 150MB per minute (1920 x 1080 pixels). So, Full HD video. Like my dashcam (I presume the camera is essentially the same as that in a phone). The hardware is probably commodity by now. My whole dashcam only cost about £30. That doesn't leave much budget for the lens. The lens is quite large (1.5cm), and wide angle (170 degrees). And yes, it's probably one of the more expensive components. I don't see why non focusing, non zoom-able lenses cost pennies to make It's still a high precision optical component, probably with four or five elements, at least one of which is probably glass. Would it also have not the one on mine a single moulded item aperture blades? that is behind the glass not within the glass |
#4
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C5 Fare Dodgers - question
tim... wrote:
"Recliner" wrote in message ... tim... wrote: "Roland Perry" wrote in message ... In message , at 20:37:27 on Wed, 23 Oct 2019, Recliner remarked: Roland Perry wrote: In message , at 19:05:11 on Wed, 23 Oct 2019, remarked: On Wed, 23 Oct 2019 09:34:49 +0100 Roland Perry wrote: In message , at 07:41:34 on Wed, 23 Oct 2019, remarked: I wonder if dashcams storing low/uncompressed video is so it can accurately capture very fast movement - eg just before an accident - which most video compression systems are not particularly good at. I think it's because they don't want to have the silicon|dollars|power budget of compressing the video. They externalise it to users having to buy stupidly big SD cards. My previous dashcam gobbled through 1.2GB for each ten minute file. There must be more to it than that. Even cheap smartphones can do realtime video compression. They produce files in MP4 format, but not very much compressed. My phone produces typically 150MB per minute (1920 x 1080 pixels). So, Full HD video. Like my dashcam (I presume the camera is essentially the same as that in a phone). The hardware is probably commodity by now. My whole dashcam only cost about £30. That doesn't leave much budget for the lens. The lens is quite large (1.5cm), and wide angle (170 degrees). And yes, it's probably one of the more expensive components. I don't see why non focusing, non zoom-able lenses cost pennies to make It's still a high precision optical component, probably with four or five elements, at least one of which is probably glass. Would it also have not the one on mine a single moulded item I'd be very, very surprised. You'd get horrible image quality, unacceptable even for a dashcam, with such a basic, single element lens. The elements may be moulded plastic, but there are almost certainly several of them. aperture blades? that is behind the glass not within the glass In all my many cameras and lenses, the aperture blades are between the lens glass elements. But a small, cheap lens like this may have a fixed aperture, with sensitivity controlled electronically. I also assume there's no image stabilisation in such a cheap model. |
#5
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C5 Fare Dodgers - question
In message , at 09:41:10 on Thu, 24 Oct
2019, Recliner remarked: In all my many cameras and lenses, the aperture blades are between the lens glass elements. But a small, cheap lens like this may have a fixed aperture, with sensitivity controlled electronically. It's much better after-dark than I was expecting. Quite an impressive dynamic range. I also assume there's no image stabilisation in such a cheap model. That would require extra processing power. My PC-based editing software will do image stabilisation post-processing, but to some extent the "wobble", or perhaps lack of, as the car goes over the level crossing [at 30.0mph] in that video is part of the experience I'm trying to capture. -- Roland Perry |
#6
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C5 Fare Dodgers - question
Roland Perry wrote:
In message , at 09:41:10 on Thu, 24 Oct 2019, Recliner remarked: In all my many cameras and lenses, the aperture blades are between the lens glass elements. But a small, cheap lens like this may have a fixed aperture, with sensitivity controlled electronically. It's much better after-dark than I was expecting. Quite an impressive dynamic range. I also assume there's no image stabilisation in such a cheap model. That would require extra processing power. My PC-based editing software will do image stabilisation post-processing, but to some extent the "wobble", or perhaps lack of, as the car goes over the level crossing [at 30.0mph] in that video is part of the experience I'm trying to capture. I think small, cheap cameras have no moving parts, so no optical IS, no mechanical shutter, no aperture blades, no lens cover, fixed focus and no optical zoom. More expensive dash cams might include some of these 'luxury features'. |
#7
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C5 Fare Dodgers - question
On Thu, Oct 24, 2019 at 08:33:02AM -0000, Recliner wrote:
Would it also have aperture blades? No. Partly because that's complicated and expensive and moving parts are likely to break, partly because you don't want the depth of field to change based on how bright it is. It'll use some combination of fiddling with exposure time and CCD sensitivity, all of which is purely done in software, to control brightness. -- David Cantrell | Cake Smuggler Extraordinaire Human Rights left unattended may be removed, destroyed, or damaged by the security services. |
#8
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C5 Fare Dodgers - question
David Cantrell wrote:
On Thu, Oct 24, 2019 at 08:33:02AM -0000, Recliner wrote: Would it also have aperture blades? No. Partly because that's complicated and expensive and moving parts are likely to break, partly because you don't want the depth of field to change based on how bright it is. It'll use some combination of fiddling with exposure time and CCD sensitivity, all of which is purely done in software, to control brightness. Yes, that's what I expected. |
#9
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C5 Fare Dodgers - question
On 24/10/2019 09:18, tim... wrote:
"Roland Perry" wrote in message ... In message , at 20:37:27 on Wed, 23 Oct 2019, Recliner remarked: Roland Perry wrote: In message , at 19:05:11 on Wed, 23 Oct 2019, remarked: On Wed, 23 Oct 2019 09:34:49 +0100 Roland Perry wrote: In message , at 07:41:34 on Wed, 23 Oct 2019, remarked: I wonder if dashcams storing low/uncompressed video is so it can accurately capture very fast movement - eg just before an accident - which most video compression systems are not particularly good at. I think it's because they don't want to have the silicon|dollars|power budget of compressing the video. They externalise it to users having to buy stupidly big SD cards. My previous dashcam gobbled through 1.2GB for each ten minute file. There must be more to it than that. Even cheap smartphones can do realtime video compression. They produce files in MP4 format, but not very much compressed. My phone produces typically 150MB per minute (1920 x 1080 pixels). So, Full HD video. Like my dashcam (I presume the camera is essentially the same as that in a phone). The hardware is probably commodity by now. My whole dashcam only cost about £30. That doesn't leave much budget for the lens. The lens is quite large (1.5cm), and wide angle (170 degrees). And yes, it's probably one of the more expensive components. I don't see why non focusing, non zoom-able lenses cost pennies to make The rest of the components probably cost fractions of a penny to make :-) -- Graeme Wall This account not read. |
#10
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C5 Fare Dodgers - question
"Graeme Wall" wrote in message ... On 24/10/2019 09:18, tim... wrote: "Roland Perry" wrote in message ... In message , at 20:37:27 on Wed, 23 Oct 2019, Recliner remarked: Roland Perry wrote: In message , at 19:05:11 on Wed, 23 Oct 2019, remarked: On Wed, 23 Oct 2019 09:34:49 +0100 Roland Perry wrote: In message , at 07:41:34 on Wed, 23 Oct 2019, remarked: I wonder if dashcams storing low/uncompressed video is so it can accurately capture very fast movement - eg just before an accident - which most video compression systems are not particularly good at. I think it's because they don't want to have the silicon|dollars|power budget of compressing the video. They externalise it to users having to buy stupidly big SD cards. My previous dashcam gobbled through 1.2GB for each ten minute file. There must be more to it than that. Even cheap smartphones can do realtime video compression. They produce files in MP4 format, but not very much compressed. My phone produces typically 150MB per minute (1920 x 1080 pixels). So, Full HD video. Like my dashcam (I presume the camera is essentially the same as that in a phone). The hardware is probably commodity by now. My whole dashcam only cost about £30. That doesn't leave much budget for the lens. The lens is quite large (1.5cm), and wide angle (170 degrees). And yes, it's probably one of the more expensive components. I don't see why non focusing, non zoom-able lenses cost pennies to make The rest of the components probably cost fractions of a penny to make :-) like all ICs but they tend to cost dollars to buy Not worked on this product class, not sure if this will be single chip solution or not? I have an unused one sitting on my shelf that I can't "give away" [1], perhaps I'll break it down tim [1] to someone deserved of being give it |
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