Lens Closer To Windshield Better?

[Street Guardian USA]

The 3D designer didn't account for the margin of error that needs to be accounted for when 3D printing objects. (Some are good others have the slight peak) The 3D design has been slightly adjusted. He didn't think there was enough support structure in the original design to space things out further. He engineered a new creative way to add additional spacing without sacrificing the support needed to hold the lens. I tested a new sample and it's perfect again (tighter too)

 

[DT MI]

The 3D designer didn't account for the margin of error that needs to be accounted for when 3D printing objects....

That makes sense. Glad to see there's follow-up taking place. Some companies would just let it go a being 'good enough'.

 

[Dashmellow]

Not just this camera - if anything the A118-C in my wife's car is worse but that could be the car and not the camera.

Yes, of course. Any camera with this form factor would have the same issue to one degree or another. Different lenses would influence how bad the problem might manifest.

I mentioned the A118 in my earlier post when I said, "ask anyone who purchased a SG9665GC or B40/A118".

 

[Rajagra]

I'm guessing that it should be possible to attach some kind of black matte plastic shield to the bottom side of the lens to block any and all reflections from the inside of the car, if the camera is so close to the windshield (in the case of SG9665GC).

That's a thought that I had, but if you think about it, you don't want the shield to block what the camera sees, just the reflection - which means the shield would have to be up against the screen just out of the camera's field of view. Not impossible, but probably intrusive in more ways than one.
I should probably draw a diagram, but I'm sure you can see what I mean.

A shield that merely blocks what the camera sees is no different to cropping the image after it's recorded. You lose part of the picture. It replaces a minor annoyance with a bigger one.

 

[Dashmellow]

That's a thought that I had, but if you think about it, you don't want the shield to block what the camera sees, just the reflection - which means the shield would have to be up against the screen just out of the camera's field of view. Not impossible, but probably intrusive in more ways than one.
I should probably draw a diagram, but I'm sure you can see what I mean.

A shield that merely blocks what the camera sees is no different to cropping the image after it's recorded. You lose part of the picture. It replaces a minor annoyance with a bigger one.

This idea has come up from time to time here on DCT but it's really not that practical because the shield would need to be rather large, way larger than the camera itself, in fact. What you guys are describing as a "shield" is really a compendium type lens shade or barn door.

A few photo examples from one such discussion are HERE, HERE & HERE.

 

[jokiin]

Thanks to my purchase of the SG9665GC I am now the proud owner of a dash mat and a CPL. The black suede dash mat I found (and enhanced) is extremely and surprisingly effective for ameliorating the reflection problem. In fact, alone it almost precludes the need for the CPL.

yes not just the angle of the window but the dashboard design and material makes a huge difference to the amount of reflection, some cars it's very minimal, others reflect really badly

 

[jokiin]

Now that is customer service as it should be.

Can you share any of the specifics as to the cause?

the design has been changed slightly to widen the opening, for the ones that get a bit of vignetting it's just catching the front edge of the CPL housing in the field of view, generally only in one corner and very slight if at all but enough to want to address the issue

 

[Rajagra]

This idea has come up from time to time here on DCT but it's really not that practical because the shield would need to be rather large, way larger than the camera itself, in fact. What you guys are describing as a "shield" is really a compendium type lens shade or barn door.

A few photo examples from one such discussion are HERE, HERE & HERE.

Yes but they've all fallen into the trap I described. They attempt to block the camera view of the windscreen, not the object being reflected.

 

[Dashmellow]

Yes but they've all fallen into the trap I described. They attempt to block the camera view of the windscreen, not the object being reflected.

No, that is not what lens shades do or how they function. Lens shades block oblique light from entering a camera's FOV (ie: the reflections) not the camera's view of the windscreen.

Perhaps you can further explain the concept of the contraption you are trying describe?

 

[Rajagra]

No, that is not what lens shades do or how they function. Lens shades block oblique light from entering a camera's FOV (ie: the reflections) not the camera's view of the windscreen.

Perhaps you can further explain the concept of the contraption you are trying describe?

Lens hoods work by blocking light that should not reach the image sensor, but does because of internal reflections from the lens elements. They do not prevent reflections off of the objects being photographed.

If you want to see through the windscreen, but not see reflections off the windscreen of other objects, than any barrier must be put between the windscreen and the object.



What I'm getting at is that depending on the camera position, it may be possible to have a shield as in the 4th picture that blocks reflections of the dashboard. But it would probably only be practical if the lens is right against the screen.
It doesn't necessarily have to be screen-mounted, but it would have to be in the right place - and probably be touching the screen.

 

[DT MI]

I'm guessing that it should be possible to attach some kind of black matte plastic shield to the bottom side of the lens to block any and all reflections from the inside of the car, if the camera is so close to the windshield (in the case of SG9665GC).

I seem to recall someone posting about that somewhere - either here in the SG9665GC thread or maybe the B40/A118 forum.

Found the thread about a 'shield' attached to the camera.

https://dashcamtalk.com/forum/threads/glare-solution.12847/

How well it might work is anybody's guess. My gut feel is to be effective it would have to be quite large and extend quite a way down and across the windshield.

 

[flip9]

Dash mat will only stop reflections of the dash. It wont reduce reflections from a mounted GPS, the headunit and instrument lights. It also wont reduce external reflections like reflective roads/surfaces and in my case i need to buy one for sand driving)

Creating a lens hood or light shield isn't an elegant solution for wide angle lenses. It wont do anything for external reflections either.

CPL will reduce both internal and external reflections day and night, but you will lose some light in the process which is a drawback for night recording.

Looking at the CPL comparison videos it doesnt affect the quality too much. There's just a bit more motion blur due to a slower shutter speed, and maybe a tad increase in gain.

The difference can be noticed in this screen cap of a comparison video. The street sign on the top left is less legible due to blurring.

 

[Dashmellow]

Lens hoods work by blocking light that should not reach the image sensor, but does because of internal reflections from the lens elements. They do not prevent reflections off of the objects being photographed.

If you want to see through the windscreen, but not see reflections off the windscreen of other objects, than any barrier must be put between the windscreen and the object.

View attachment 19741

What I'm getting at is that depending on the camera position, it may be possible to have a shield as in the 4th picture that blocks reflections of the dashboard. But it would probably only be practical if the lens is right against the screen.
It doesn't necessarily have to be screen-mounted, but it would have to be in the right place - and probably be touching the screen.

I think we can agree that lens hoods will not cure the problem of reflections in one's windscreen.

Your illustrations are rather amusing as they do not represent how light and optics actually behave in the real word but I get what you are attempting to convey.

On the other hand, your concept of having a windscreen mounted "shield" seems quite goofy I'm sorry to say as it could never work regardless of how close you can get the lens to the windscreen. Such a "shelf" would need to be as wide as the entire dashboard and would not only block the camera's view of a good portion of the road but would likewise block the driver's view of the road as well. Your idea is just a flight of fantasy which ignores optics, physics and how a dash cam's FOV sees the road.

 

[Dashmellow]

Found the thread about a 'shield' attached to the camera.

https://dashcamtalk.com/forum/threads/glare-solution.12847/

How well it might work is anybody's guess. My gut feel is to be effective it would have to be quite large and extend quite a way down and across the windshield.

I remember that thread. Basically, it is the same concept of the photographic "barn door" light shield I described earlier in this thread (shown below), which would not work. You are quite correct that it would have to be extremely large and would need to extend across the entire windshield. This is the same problem that would be encountered with @Rajagra's, concept as mentioned above.

 

[jokiin]

if you want to see these types of lens shields in practice have a look at the top of the range Mercedes Benz models that have cameras in the window, they're not for recording though and aren't as wide angle so much easier to deal with

 

[Dashmellow]

Yes, the camera in the new Corvette is in it's own glass mounted housing quite similar to that. With such an integral housing directly against the glass reflections would never be an issue.

 

[jokiin]

Yes, the camera in the new Corvette is in it's own glass mounted housing quite similar to that. With such an integral housing directly against the glass reflections would never be an issue.

the benefits the OEM's have over anything aftermarket, always better results when things can be integrated to the vehicle

 

[Dashmellow]

It would be interesting to see a dash cam designed specifically to accomplish the same idea. A camera designed with an appropriate lens surrounded by a compendium type lens shade could conceivably be attached to any angle windshield.

 

[jokiin]

It would be interesting to see a dash cam designed specifically to accomplish the same idea. A camera designed with an appropriate lens surrounded by a compendium type lens shade could be conceivably be attached to any angle windshield.

have thought about something like this, the wide viewing angles do make it a challenge and the lens would need to be as close as possible to the glass to at least reduce the size of the shroud needed but I suspect it would still end up quite large and fairly unattractive

 

[Dashmellow]

have thought about something like this, the wide viewing angles do make it a challenge and the lens would need to be as close as possible to the glass to at least reduce the size of the shroud needed but I suspect it would still end up quite large and fairly unattractive

I agree that I might be large but perhaps such a thing could be designed to look OK. I envision something like an elongated black wedge that could be made to look like it is supposed to be there.

If it completely eliminated reflections it might be a reasonable trade off.