ALL Dash Cams Have Distortion- "Bending Images"

Chode said:
This question doesn't make any sense at all. What 'millimeter' are you referring to? Focal Length? It won't tell you anything, unless you know the frame dimensions (i.e. sensor size in digital imaging). Physical size? Why would you want to know that, and what possible use could this datum provide?

I couldn't bring myself to read this entire thread, but I went through enough posts ... so here goes:

Practically all lenses have their Field Of View expressed in degrees (º) measured DIAGONALLY. You seem to think this is something new or part of the great conspiracy by dashcam manufacturers. I can assure you it was already an established practice before the advent of a motorised carriage, never mind the dashcam.



Diagonal Field Of View is one of the most important parts of any optical lens specification



What are these mysterious "Degrees ( °) of the Wide Angle Lens"? Whether wide angle, or tele-, or whatever lens - DIAGONAL FIELD OF VIEW IS MEASURED IN DEGREES!

Oh, and if you want to avoid optical distortion at the point of image creation, either get a lens (with a desired DIAGONAL field of view) the size of your car, or decree to abolish the laws of physics 😉
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O.K., if you wish to speak in "diagonal" terms, 'What is the diagonal measurement ( LENS) on the Mini o803 > "135" > "143" > "155" > "160" , or am I not presenting myself clearly?
 
JooVuu said:
Yes we are? I do not follow your response to the questions and statements we wrote?

Kind regards

JooVuu
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Are you not on Facebook, Twitter, and have a blog? Exactly, who writes or elaborates on the specifics of dash camera's? Are there a variety of people being allowed to define technical specifications?
 
Answers in red:
synoptic12 said:
Changing gears briefly, I'd like to know of the 'recycle, or 'loop' settings which are in increments of 1, 3, and 5 minutes. I understand this sets the file size and length for each recorded segment, but would like to know why there is a setting ( 3 modes) to accompany the recycling. If one is continuously recording to capture video, why would any opt for 1 minute, as opposed to 5 minutes? No Idea, I always use 5 minutes as it should be slightly more efficient in disk space and file transfer time. Most have suggested 1 minute but what is the reason for this? No Idea. What I see is that each clip will be spliced at 1 minute for the 'default' setting. Why would one decide to have short splices ( 1 minute) rather than 5 minute? No Idea. For instance, one is driving for one hour while recording video with an 8 GB internal memory ( No external card), why would any set 1 minute duration instead of 5 minute? No Idea. Additionally, when would the loop or 'recycle' process take affect; A. Once the card is filled as per overwriting? When the card is full the oldest file is recycled and used for the newest. Why would any set the 'recycle' option to "off"? No Idea when being used as a dashcam. We believe that the maximum recorded file is 3.66 G upon setting the recycle to off. Is this simply for the fact of NOT overwriting? Due to the use of FAT16 card format which has a maximum file size.

One last question please (too many questions!) , 'How long, or how many minutes of video would one obtain via an 8 GB internal card? Depends on the selected resolution and quality settings, most of an hour at maximum resolution and quality, far more at 720 resolution. Why have 32 0r 64 G when the camera continuously overwrites? To keep older video for longer before it gets overwritten, sometimes it's nice to look back at something that happened near the start of your trip. All responses are most appreciated.
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synoptic12 said:
Are you not on Facebook, Twitter, and have a blog? Exactly, who writes or elaborates on the specifics of dash camera's? Are there a variety of people being allowed to define technical specifications?
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Aside from this triviality, can you address one of my previous comments about the Mini 0803 Lens (size)? Posted three times and have not received a definitive answer.
 
synoptic12 said:
Thank you. Seeing that you may be available, could you address one of my previous questions regarding the "size" of the Mini 0803 lens?
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No, all I know is that it shows the majority of my windscreen, just cutting off the edges and thus is quite close to what I actually see in real life which I find quite nice. That does introduce some distortion at the edges but not so much that I notice it unless I am looking for it.
 
Nigel said:
Answers in red:
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Thank you very much for the response. Why do you believe that so many 'not useful' settings, or settings that do not actually work be incorporated in a camera?
 
Nigel said:
No, all I know is that it shows the majority of my windscreen, just cutting off the edges and thus is quite close to what I actually see in real life which I find quite nice. That does introduce some distortion at the edges but not so much that I notice it unless I am looking for it.
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That response is simply absurd to the question I posted.

A.) WHAT IS THE WIDE ANGLE LENS SIZE: 135, 143, 155, OR 160?
 
Nigel said:
No, all I know is that it shows the majority of my windscreen, just cutting off the edges and thus is quite close to what I actually see in real life which I find quite nice. That does introduce some distortion at the edges but not so much that I notice it unless I am looking for it.
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P.S. - I would definitely agree with you in this aspect.
 
synoptic12 said:
Thank you very much for the response. Why do you believe that so many 'not useful' settings, or settings that do not actually work be incorporated in a camera?
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I suspect it is historical from when a 1 minute long file overwhelmed the transfer speed and processing power of PCs and memory cards. People still expect the options to be there and some will still use them. I think they should add a 10 minute option to match modern hardware speeds.

As for the use of FAT instead of exFAT which would be correct for XC cards, that is simply due to licencing costs.
 
Moving to the secondary segment pertaining to 'quality'. Would any know if there any dash cams employed with CCD, as opposed to CMOS?
 
Nigel said:
I suspect it is historical from when a 1 minute long file overwhelmed the transfer speed and processing power of PCs and memory cards. People still expect the options to be there and some will still use them. I think they should add a 10 minute option to match modern hardware speeds.

As for the use of FAT instead of exFAT which would be correct for XC cards, that is simply due to licencing costs.
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Thank you very much. You have certainly clarified this issue for me.

P.S.- Would you have any knowledge of the s/n ratio on the Mini 0803?
 
synoptic12 said:
O.K., if you wish to speak in "diagonal" terms, 'What is the diagonal measurement ( LENS) on the Mini o803 > "135" > "143" > "155" > "160" , or am I not presenting myself clearly?
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As far as I recall, previous attempts have been made to answer your question. This camera is being offered with several different focal length lenses. For example, FoxOffer states that the 803 they are selling has a 143 degree FOV. The 803 sold by Spytec states theirs is 120 degrees. JooVuu doesn't state a FOV in their offerings for this model (they may have a good reason). It's best to confirm with the vendor which lens is on the camera before purchase if the degrees of FOV is that critical for you. Suppliers, production runs and other factors might change the exact specs of the stock they have on hand at any given moment.

Going back to your initial concern about "Bending" images when you started this thread, the optical phenomenon your are describing is called "barrel distortion". The wider the angle of the lens you choose, the more "bending" (ie: barrel distortion) you will see. This is just the nature of wide angle optics. Some recent camera DSPs have begun to include a "de-warping" function which is basically a built in firmware filter that attempts to correct for this optical aberration. The chipset in the 803 has this feature but personally I don't know if it is enabled in this camera.

Here is a graphic that gives a visual representation of different degrees of coverage one can expect from different focal length lenses. The wider the FOV (in degrees), the more barrel distortion you can expect.

FOV.gif


Here is a graphic that demonstrates moderate barrel distortion:

600px-Barrel_distortion.svg.webp
 
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synoptic12 said:
Moving to the secondary segment pertaining to 'quality'. Would any know if there any dash cams employed with CCD, as opposed to CMOS?
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I suspect you wont find any mainly due to CCDs having too low an ISO rating. At 30 fps you would not be able to capture any night footage. They also struggle to achieve 30fps at decent resolutions.
 
Nigel said:
I suspect you wont find any mainly due to CCDs having too low an ISO rating. At 30 fps you would not be able to capture any night footage. They also struggle to achieve 30fps at decent resolutions.
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Are not Motion Picture Standards at 24 fps?
 
synoptic12 said:
Thank you very much. You have certainly clarified this issue for me.

P.S.- Would you have any knowledge of the s/n ratio on the Mini 0803?
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All noise is lost in the video encoding, all the "noise" you see in the end result is encoding artefacts (equivalent to jpeg noise) and the level of that depends on the quality setting selected, at best quality I don't see any noise when watching the videos.

The sound does have some noticeable background noise.
 
Here's an easy question, how would one know when the file is full (Mini 0803)? Is there any way to determine this by viewing the (camera)screen? Did not wish to overwrite files using a 8 GB internal memory only. I'm aware of the external memory capabilities, but see no need for external memory; other than to remove the card and not the camera.
 
Nigel said:
All noise is lost in the video encoding, all the "noise" you see in the end result is encoding artefacts (equivalent to jpeg noise) and the level of that depends on the quality setting selected, at best quality I don't see any noise when watching the videos.

The sound does have some noticeable background noise.
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Yes, I am aware of those characteristics, but is there a technical spec for the s/n?
 
synoptic12 said:
Are not Motion Picture Standards at 24 fps?
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It's a dashcam, it does 30fps, another historical legacy of older dashcams supporting NTSC/PAL video output. Although 30 is a sensible frame rate for an accident cam.
 
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