Field of view?

[crabu2]

I have a broken Vanture N2 Pro that records at 170 deg. I like how wide it can see. But since my bad experience was Vanture, I'm looking to get a cheaper dash cam.

I'm not looking at Viofo because they look to have excellent reviews for their price range, but I see they have 3 difference A119 models. Each has a different field of view. 160, 135, 130.

My question is, is there much of a difference? With the 170 on the N2 Pro, using the suction mount, I could see the A pillars of the car. Will I get that or close to it with something like the A119 Pro, which only sees at 130?

Thanks!

 

[jokiin]

got a screenshot from your old camera that shows the field of view?

 

[Nigel]

With the 170 on the N2 Pro, using the suction mount, I could see the A pillars of the car. Will I get that or close to it with something like the A119 Pro, which only sees at 130?

Thanks!

I would expect that if you used a suction cup with the A119 or A119 pro then you would just about see the A pillars, without the suction cup the camera is further forward and with a normal curved windscreen the camera lens is forward of the A pillars so there is not much chance of seeing them, but the field of view has not changed by moving it forward.

With the lower resolution A119S I would expect a narrower field of view so that it can still read number plates.

Some of these FOV are horizontal FOV of the image, some are diagonal, and some are the FOV of the lens which produces a circular image slightly wider than the diagonal of the sensor - it is not good to compare numbers!

 

[crabu2]

got a screenshot from your old camera that shows the field of view?

WIsh I did, but I don't.. I repurposed the SD card that I was using.

 

[crabu2]

WIsh I did, but I don't.. I repurposed the SD card that I was using.

BTW, I really did like the N2 Pro because I was getting a recording of inside the car. I'm going to miss that with a new dash cam. But I learned my lesson with Vanture. If they couldn't even respond to my email asking if I could just buy a new lens... well that tell me a lot.. That the company really doesn't care.

 

[jokiin]

WIsh I did, but I don't.. I repurposed the SD card that I was using.

did it match this? https://dashcamtalk.com/forum/threads/vantrue-n2-pro-vantrue.30288/

 

[SawMaster]

The N2 Pro may advertise 170 degrees but I'm certain mine doesn't do that. Looking at the clip I placed in my review HERE I'd say it's actually more like ~140 degrees horizontally (which would go higher diagonally). Aspect ratio can also skew the numbers. But really, what matters to us with dashcams is the horizontal FOV; I've never seen a cam lacking vertically.

If you want truth in FOV you need to look at clips and vids people have posted of the cam you're thinking about. That way you can see for yourself what the cam sees

Phil

 

[kamkar]

with 170 degrees and a camera like the N2pro that don't sit very close to the glass, you would more or less see all of both A pillars in the footage.
And i cant say i can recall seeing a dashcam with a that wide FOV

Judging from youtube videos the N2 pro actually look as if it have a fairly narrow FOV, or at least not a exceptional wide FOV.

 

[jokiin]

The N2 Pro may advertise 170 degrees but I'm certain mine doesn't do that. Looking at the clip I placed in my review I'd say it's actually more like ~140 degrees horizontally

Would be lucky to be 120 going by the video, this is what makes it hard when people just look at numbers

If you want truth in FOV you need to look at clips and vids people have posted of the cam you're thinking about. That way you can see for yourself what the cam sees

the best advice

 

[SawMaster]

My cam sits about in line with the top of my A-pillars due to windshield curvature and mounting or maybe 1" (25mm) behind them. 170 degrees would at least 'see' the bottoms which aren't visible. On a few cams I've actually used poles beside the car to mark the vid edges, dropped a plumb bob to the dash from the cam lens, then aligned a protractor to that point and sighted to my poles from that. This will give an accurate horizontal FOV measurement and none I've tested like this even comes close to the listed specs. I might do that for my current cams just for the heck of it- if I do I'll post the results here.

Phil

 

[crabu2]

did it match this? https://dashcamtalk.com/forum/threads/vantrue-n2-pro-vantrue.30288/

Yes,but I'm pretty sure I could see the bottoms of both A pillars. It's a small car (BMW 2 series).

 

[jokiin]

Check the video of any models you're interested in, don't go by the numbers, the Vantrue is overstated by more the 50 degrees which makes comparisons worthless if relying on published specs

 

[Nigel]

with 170 degrees and a camera like the N2pro that don't sit very close to the glass, you would more or less see all of both A pillars in the footage.
And i cant say i can recall seeing a dashcam with a that wide FOV

I can see "more or less see all of both A pillars" on my cabin camera, problem with that is that I need to use the rear camera to be able to read any plates behind the car, even though the cabin view is 4K resolution! A wide FOV comes with disadvantages as well as advantages, best is to have both.

 

[SawMaster]

Yes, better to have both but IMHO if you only have one it should be wide-angle. What you're usually going to need to show is the position and movement of all the involved vehicles which includes those to the sides and on the crossing road at intersections- the big picture. Details like plate capture become more important when an involved vehicle drives off from the scene of the incident, which normally doesn't occur. Ideal would be wide-angle which has the sharpness and detail of a Hollywood movie in every situation, but you'll never see something like that in the small economical package we need with dashcams. Every dashcam is a compromise so choose what you prefer. You can always swap out or add cams in the future (says the guy who has 7 cams in his workvan ATM; this can get addicting )

Phil

 

[Nigel]

Yes, better to have both but IMHO if you only have one it should be wide-angle. What you're usually going to need to show is the position and movement of all the involved vehicles which includes those to the sides and on the crossing road at intersections- the big picture.

If you follow that rule to the ultimate then you would start with one 360 degree camera and then add a plate reading camera later. But I've not seen many 360 degree cameras being used as dashcams so I'm not convinced it is that simple! I like to have at least some chance of reading a plate in good lighting conditions.

In my image above, the door mirrors are behind the camera yet it can see them so I must have around 210 degrees there, front image is about 140 degrees leaving a small gap either side.

 

[SawMaster]

First, nobody makes a 360 degree cam I'd want to use for dashcam work. Nor do I like the way such images are currently depicted. They have drawbacks involved some of which also would happen with a 180 degree cam. And when you reach these extreme angles distortion usually creeps in. So don't be taking what I say to extremes

I think everyone else understands that by "wide" I'm referring to what the current quality dashcams have which run to around 140 degrees max. To get beyond that you'd be better served with side cams both to eliminate view blockages and to reduce distortion. But before those I feel a rear cam matters more. Maybe these are more important than a telephoto; I personally think they are.

But even a telephoto with perfect plate capture isn't going to get them all because of the narrow FOV and in places without front plates (like where I live) you'd want on in the back because now you're seeing only the type of car and a driver's face for ID purposes unless they overtake you, allowing a view of the rear of their car. It's not going to show cars to your sides or angling towards you. All a telephoto up front does is increase your chances of plate capture on a very small portion of the cars around you that might affect your driving. And even then any of those cars could have stolen plates.

So there's no single perfect solution- perhaps no perfect solution at all. The best approach is to handle the most likely needs first and since most folks use just one front cam, that would be best done with a cam which captures well as much of the view as is practical- ie a normal wide angle cam- so as to show as much of the action that affects you as can be practically done

Phil

 

[SawMaster]

In my image above, the door mirrors are behind the camera yet it can see them so I must have around 210 degrees there,

Not horizontally; not even close. Most folks who do not regularly deal with angles (or distances either) have poor estimating skills regards them. Use the method I mentioned in post #10 (or something with equal or better accuracy) and see for yourself. I promise you that the results will surprise you- they did even with me because most of my work with angles are with much more acute ones.

Phil

 

[Nigel]

Not horizontally; not even close. Most folks who do not regularly deal with angles (or distances either) have poor estimating skills regards them. Use the method I mentioned in post #10 (or something with equal or better accuracy) and see for yourself. I promise you that the results will surprise you- they did even with me because most of my work with angles are with much more acute ones.

Phil

Yes, horizontally. The camera is mounted behind the rear view mirror, the door mirrors are further forwards on the car than the camera, attached to the front of the A-pillars, right at the front of the windscreen, so if the cabin view image from the camera was only 180 degrees horizontally then it would not be able to see the door mirrors at all, instead it can see an image reflected in the mirrors, if it can see the reflective side of the mirrors the camera must be mounted further back on the car than the mirrors and is looking forward to see the mirrors. As for the outside view, between the 140? degree front image and the cabin image, the only part of the 360 that I am missing is the doors on that silver car and the same on the opposite side, I have the front of the silver car in the front image and the rear of the car in the cabin image, if its doors cover 5 degrees then 210 + 5x2 + 140 = 360. Must be somewhere close to that.

 

[country_hick]

You can try different fields of view and resolution levels using this site.

IPVM Designer / Calculator

Using Google Maps, layout and design cameras, choosing from 10,000+ models, delivering FoV and image quality previews plus export to PDF, Powerpoint and more

calculator.ipvm.com

Although it is not set up for dash cam use this site allows you to see how different fields of view effect what can be captured by a camera. Pay attention to the ppf number. Anything less than 38 ppf {pixels per foot} (40ppf according to many sources) means you will not be able to capture necessary details such as license plates and facial features. If the conditions are not ideal you may not get useful details at this level. This is why capturing license plates is so difficult with dash cams. Even ignoring the lower resolution most dash cams have (1080p) and ignoring motion blur a wide angle lens simply lacks the capability to capture these precise details.

Add a camera. You get a generic camera that allows you to manipulate its settings. You can change from 1080p to 4k You can make the field of view wider or narrower by using your mouse on the end of the green cone of coverage. A 4k camera with a field of view of 120 degrees is only good for precise details up to 28 feet. The same 4k camera with a 140 degree lens is only good for 17 feet. But put a 60 degree lens on the same camera and you can capture usable images such as license plates at 83 feet with a much narrower field of view..

 

[SawMaster]

the door mirrors are further forwards on the car than the camera,

In other words they are LESS THAN 90 degrees to the lens each, which is LESS THAN 180 degrees total. 180 degrees horizontal is a line connecting two points directly beside the cam left and right, with the lens of the cam being on that line between those points.

I never thought I'd have to explain 6th grade geometry here.

Phil