Question about dash vs. horizon ratio and CPL filters

[vortigos]

So I finally got my Vifo A119 up and running, and I wanted to get your expert opinions on the adjustments I've made in order to see if they're optimal. In the daytime picture below, I'm curious if my cam is angled a bit too high and is capturing too much horizon and not enough dash. Does it looks pretty solid as is?

Second question, you can see in both the daytime (above) and nighttime (below) grabs that I'm getting a good amount of reflections, especially in the lower left and right hand corners. On the night shots, you can see that in very dark conditions there's large triangular black sections in the corners where the cam doesn't pick up anything, but they do correspond to the high-reflective areas seen in the daytime photos. You can see in the second night grab that once there's some light coming overhead in the right corner, the cam does pick up the image accurately.

Would the CPL filter mostly eliminate my daytime glare and perhaps some of the dark reflective corners in the night shots? Or would it only take care of the daytime reflections?

 

[David 777]

I bought my A119S with a CPL as it came as a good package deal. I knew the difference polarised spectacles made, so decided a CPL would probably be a good idea. I experimented with and without CPL. The lack of glare from other vehicles was well worthwhile and happy purchased the CPL in the bundle. Can't offer any info on night driving as didn't try at night.

 

[kamkar]

The rule of thumb is 60/40 split ( below/ above ) on the horizon, but some cameras can do 50/50.

You can always experiment a little on this with your camera, cuz it is not like a little too much to one "side" is totally messing up the footage.
If you have the camera up high then in daytime street level might be a little too dark, night time should not see any change as up high is also dark by then.
And too low i assume is no problem other than you will see plenty of dashbord, and might miss the color of lights as you approach intersections.

I am not sure if a CPL filter on the camera change this fact, i have not been using CPL filters on my cameras much, i am working on making my own dashmat as my little Suzuki is not supported by companies that make dashmats.

That said a good low light dashcamera can handle a CPL filter in low light, sure end footage will be a little darker, but the things in the footage that's actually something you can use in case of a dispute will still be good enough.

I don't mind if skies are a little blown out, what is at street level is my concern and everything else is just icing on the cake.

 

[vortigos]

Thanks to posters so far. Any other opinions?

 

[Hillbilly]

33% sky, rest road and dash works for me for couple of years

 

[Harsh]

Even if a CPL doesn't darken the video to a discernible extent, it definitely lengthens the exposure time and introduces additional motion blur.

 

[DT MI]

There are no 'hard and fast' rules about this - just starting points. The color of your dash and hood will affect exposure to a significant degree, which will vary by camera and the exposure options each camera might have. You'll just have to go through a trial and error period with your camera in your car and see what works. When I've had the same camera in 2 different vehicles (one silver with black dash, the other dark red with dark brown dash) and what worked for one did not in the other.

The one thing that I always strive for is to have some portion of the vehicle visible in the frame so the relationship of objects in the video to your car are obvious.

 

[castle]

To me, the primary function of a dashcam is to capture information so you can review later in case of an event, and the more information captured, the better. Getting a "pretty" picture is a secondary concern. Most dashcams I have seen seem to compensate adequately for the amount of sky in the picture.

So the choice is between tilting down and seeing more of the vehicle hood or dashboard, and tilting up and seeing more above the horizon. If what's above the horizon is always blue sky, then I would agree that it's an equal trade-off between car hood and sky. But it's not always blue sky. If you are in a parking garage, what's above the horizon is other vehicles and people and objects in the garage, and it might be useful to capture them. If you are in the city, you would see buildings and people and things also, so in these less open spaces, it's more interesting to look out beyond the car than down at the car hood.

Bottom line is that I would tilt low enough to see the nose of the car, but not much lower. In the picture in the first post, I would adjust the dashcam up one click. Too much car hood and dashboard in my opinion.

 

[Zardoz66]

The way I have my A119 V2 set is to get just the nose of the car. So maybe the lower 20% or less is car hood. the rest is street and sky. the official A119 CPL is made to be used in day and night so it does not cut night performance down to much. I did bump my exposure to 1/3 and it seems fine. dont expect awesome glare reduction, but it does help.

 

[jokiin]

dont expect awesome glare reduction, but it does help.

they're only being used to deal with dashboard reflections, generally won't help at all with glare, not intended to though

 

[HeePee]

Well, look at the difference. Better not to point to the sky. With part of the dashboard gives you a much better light balance. (A119 + CPL)
https://www.dropbox.com/s/s7n3vlt5mto1pg2/Viofo A119 - Camera sky or dasboard - with CPL.MP4?dl=0

 

[Rajagra]

The only serious problem I've encountered is that if you have a camera pointing directly forwards (horizontally), there are times it ends up pointing at too much sky and this darkens the image so much that you can barely see what's lower down, i.e. the road and vehicles. Tweaking the video in VLC etc may be able to correct this, but prevention is better than cure.

Pointing down slightly fixes this. A graduated grey filter would be a great fix, but not very practical (unless it was a built-in feature, hint, hint). My previous vehicle had a graduated sun screen strip at the top of the windscreen and that worked brilliantly too.

It would be nice if dash cam firmware recognized that sky is not of interest and had an option to prioritize exposure settings for the lower 2/3 of the image. Very easily done, I'm sure.

 

[SawMaster]

Still on my first coffee so might be wrong, but I believe the M2 has selectable light metering

Camera aim is how you control this with most cams and too much sky can be problematic if it upsets the metering. For me as long as I see enough of the car to judge distances and also see the horizon then I can live with it. I do prefer to aim high enough to capture overhead traffic signals when at the edge of the intersection as those are commonly used here. Like adjusting exposure settings, aim is just another variable you work with until you get your best results and that will vary for different cars, cams, locations, and users.

Phil

 

[Deleted member 46308]

I do prefer to aim high enough to capture overhead traffic signals when at the edge of the intersection as those are commonly used here

Phil

A priority of mine as well.

 

[Rajagra]

Don't know about the M2, but the usual metering options are average, centre-weighted, or spot.
What dash cams need is metering that is very heavily weighted to account for what's below the sky line. None of the above 3 types do this.

Edit> Maybe there's an even better, simpler way. Here's an image where auto-contrast has been used. Then I've used the Equalize function in Photoshop. Normally you would avoid this like the plague because it makes a photo fugly. But we are interested in pulling out detail, so...


If a dash cam had an Equalize exposure mode it might be pretty good. I wonder if VLC can do this to video. It would be best to do this before the original recording though.

 

[Zardoz66]

they're only being used to deal with dashboard reflections, generally won't help at all with glare, not intended to though

Sorry I kind of bundle it all in one may you call it glare or reflections. I understand they are different...

 

[Zardoz66]

Well, look at the difference. Better not to point to the sky. With part of the dashboard gives you a much better light balance. (A119 + CPL)
https://www.dropbox.com/s/s7n3vlt5mto1pg2/Viofo A119 - Camera sky or dasboard - with CPL.MP4?dl=0

Thanks for the video. the sample does show some change but again not all of it is gone only a persentage. I can tell you that I do not have my cam pointed up, but a little more down angle. but the video does show how angles effect dash reflections. Don't get me wrong it works it's just me expecting more.

 

[HeePee]

Thanks for the video. the sample does show some change but again not all of it is gone only a persentage. I can tell you that I do not have my cam pointed up, but a little more down angle. but the video does show how angles effect dash reflections. Don't get me wrong it works it's just me expecting more.

Your welcome. But the video was not about to show a difference in reflection or glare. It's about how well (brighter, clearer) you can see things on the road when pointing the lens a bit down. (Due to a better light balance)