vote for image sensor

[kamkar]

As long as low light ( not even night ) is still such a problem for dashcams i see no reason to go up in resolution, so i think that better low light performance will hit first in the 1080P resolution.
And i would prefer to move avay from SD cards for storage, and so i will have to go avay from the current way of having a box with it all in mounted on my windscreen, cuz i will not like a huge dashcam with a 3" screen on my windscreen, or rather i would take that too if it would then give me much better low light performance than now.

I like 4K but i cant see me getting anything i can play that back on, not a new computer monitor ( need a new one but i will go for 1080p ) or a new TV ( have working 1080P TV so no need there )

Only reason i can see me getting 4K anything would be if i suddenly had a lot of money to burn, but in that case i would have to go travel for a long time first to get my hardboiled brain resat back to normal ( if possible )

 

[arcticfire]

I'll take a four channel 1080p (or even 720p) over 4k any day.

Could a cam automatically switch between 4k and 1080p when it needs low light performance? I guess it would need some sort of ability to merge the photosites to effectively convert it into 1080p to gain the low light advantage but I don't even know if that's technically possible?

 

[kamkar]

I dont think that will help @arcticfire cuz better low light performance is based on the pixels on the sensor beeing larger.

Offcourse if a larger sensor was able to bin say 4 pixels into 1 that might do it, but i am not sure thats how it work or if thats doable.

 

[arcticfire]

Aye that's what I mean, could they somehow merge several into one but I can't really see how that would be technically possible.

 

[Dashmellow]

Aye that's what I mean, could they somehow merge several into one but I can't really see how that would be technically possible.

I'll take a four channel 1080p (or even 720p) over 4k any day.

Could a cam automatically switch between 4k and 1080p when it needs low light performance? I guess it would need some sort of ability to merge the photosites to effectively convert it into 1080p to gain the low light advantage but I don't even know if that's technically possible?

As @kamkar1 points out, I'm not sure doing that would help in this situation but this is commonly done with a process called Pixel Binning, so conceivably one could use only a portion of a 4K sensor for 1080P capture. For example, the Mobius shoots in "Wide Mode" reducing its native 2304 x 1296 sensor area to 1920 x 1080 via pixel binning. If you switch to "Narrow mode", the image is captured at 1920 x 1080 directly from center-most portion of CMOS array with no scaling. This process is also used in 720P mode.

See this LINK for a further explanation of Pixel Binning.

 

[arcticfire]

Not sure that would help for low light though as the photosites would still be the same size, it's more along the lines of being able to merge photosites so each one becomes physically bigger in the lower resolution. I don't think it's technically doable though.

 

[Dashmellow]

Not sure that would help for low light though as the photosites would still be the same size, it's more along the lines of being able to merge photosites so each one becomes physically bigger in the lower resolution. I don't think it's technically doable though.

Yes, we are saying essentially the same thing regarding low light. Pixel binning is used in a variety of ways however, such as its use in astro-photography to enhance information and detail from the available input.
I was specifically referring more to your question: "Could a cam automatically switch between 4k and 1080p". Yes it can.

 

[arcticfire]

Is that what dlsrs are doing when a full frame is shotting in crop mode?

You missed the bit at the end though where I said for low light performance. I can't see how pixel binning would help here but I don't know the technical side of it.

 

[Dashmellow]

Actually, I didn't miss the bit about low light performance. That's why I said, "I'm not sure doing that would help in this situation", but spoke of how pixel binning is often used to capture a portion of the sensor. Truth is, I don't know a whole lot of the technical side of this either but thought it might address your question about switching resolutions on the fly and lead to some interesting discussion.

 

[arcticfire]

So, does anyone know if photosites can be grouped together to act as one larger photosite? I know there are sensors which now eliminate the gap in-between sites, but even being together without the gap can they act as one photosite?

Would be quite cool having 4k during the day and then 1080p low light performance at night.

 

[Dashmellow]

It would be cool to have a 4K/1080P camera.

One alternative solution that has been discussed here on DCT previously on several occasions has been the concept of having a single camera with two separate sensors and lenses. This is often done on CCTV cameras where the cam switches over to a different, faster lens and separate night-time optimized sensor at around .5 lux and then back the other way at sunrise. In fact, I've had one of these in service for six years now and the performance is spectacular compared to similar single sensor cameras. Anyway, I would love to see a dash cam developed around this concept using a 4K sensor and a 1080p sensor. At one time I considered using two side by side Mobius cameras optimized for day and night and may even still do that one day.

 

[arcticfire]

I reckon one challenge with proper 4k in dashcams is going to be the storage, especially if it's going to be decent quality 4k. I think this is where some form of external recording device is going to be necessary to get any decent length of footage and also the reliability. I'm not sure how many people would want to shell out for a 512GB+ card when there are so many issues at present with card compatibility and reliability.

 

[DennisOlof]

Just like others have stated.

4k is nice but to problematic in lots of ways.

1080p 60fps and larger sensors, like micro four thirds, och 1 inch should fix the problem of bad image or low lite conditions.

This is true for a lot of Panasonic DSLR that have the "micro four thirds" size sensor, and are mostly 16mpixel, but they are a nice
balance between migapixel quality and low light. Should be optimal for use in dashcams. And since we are staying at 1080p 60fps
these chips are cheap now.

So the only real downside is that the sensor will push the cost up, but it might not be a bad thing as people might be willing to
put up that money for the improvements in image quality and low light preformance.

I have not seen any dashcam that has a larger sensor, they are still the same as smartphones more or less, some do have
lower megapixel count to get better low light performance. Same thing for action cams. Looks like we are stuck at a specific
sensor size, nothing new is on the horizon, not that I know of.

 

[2000rpm]

A big problem for dashcams is the first lens the light has to pass through.
Also known as the windscreen.

 

[DennisOlof]

200rpm, HAHA true.

And not only that, it has a angle, it is curved, plus gets dirty. Impossible to compensate for that, you will get image
distortion no matter what you do. Plus there will be sunspots, glaring in the window (ghost image).

But I really wish they would go with a "1 inch" or "micro four thirds" sensor, that will do wonders for
driving at night plus improve the quality in daytime video as well. Even if the cost is higher, they could
have a version like that, for the people who want that. More expensive but some might be willing to
put money into that.

As of now, I know of no dashcam that has a larger sensor that what is standard (like in mobile phones).

There are one or two actioncams but they have other problems.