"i think, judging from your pic, there's a fair gap between lens and window which i would think always for all sorts of reflection problems."

Actually, no. The lens hood is less than half an inch from the windshield, so that the lens is probably at most an inch and a half away.

Like Ushere I've done this only with a locked-down camera with careful light baffling. So, looking at the physics of the problem we're shooting at an angle through a thick glass sheet, and we want freedom to pan. Currently your sensible steps to minimise reflections from dash and interior have not eliminated the problem. Light reflected from glass is highly polarised only when the angle of incidence is 57 deg (affected by refractive index), so at all other angles your polar filter will be limited in effectiveness. Also has potential to make visible strain in the windshield (very obvious with toughened glass). It isn't practical to coat your windshield with anti-reflection coatings (as used on lenses) so all you can do is cut the source. Black velvet is the excellent for absorbing light, so continue with your present approach. Get the lens as close as possible to the glass. A matte-box or a black annular mask to fit over the lens will reduce the ability of the lens to see reflected things. This can be set up to work fairly well for a locked-down camera. If you could drape black velvet generously around, it might do your trick (probably not compatible with other passengers!)

Among the insoluble problems are separate reflections from the front and back surfaces of the glass, and their separation and intensity will increase as the angle of "look through" diminishes.

>>>cpl is useful, but as you've already noted, would need adjusting according to the sun's position<<<<

Only the angle of the glass (trying to stop reflections from the windshield).

This is the only real attempt at filming through a windshield I've done:

car windshield video[/link]

My setup wasn't as fancy as yours. I had my camera on a tripod (legs not extended) and strapped to the passenger seat with bungee cords.

I do now have a suction cup car mount for my camera, so next time I do a car scene, I may have the cam outside the car stuck to the roof.

Thanks Serena for your reply. Could you explain a bit more "Also has potential to make visible strain in the windshield (very obvious with toughened glass). " and "Among the insoluble problems are separate reflections from the front and back surfaces of the glass, and their separation and intensity will increase as the angle of "look through" diminishes. "

The setup picture you see is my wife's car, a 2010 Honda. I shot video on a road trip last fall and quite frankly, it was not nearly as good, as some taken a year earlier in a much older Chevy Suburban in which the camera was mounted much farther behind the windshield. The windshields in the vehicles are different--the one in the Honda more sloped and the other more upright since it's basically a truck.

The closer you can get to shooting normal to the glass (ie glass square to the optic axis of the lens) the fewer problems. Both the front and rear surfaces of the windshield reflect light, and light passing normal to the surfaces loses about 5% by reflection at each surface. The proportion reflected increases as the angle increases (as you can see by experimenting), and because the surfaces are displaced by the thickness of the glass so the reflected images are not coincident and the steeper the angle the greater their relative displacement. This isn't very obvious when the scene outside is much brighter than that inside, and negligible if you can black out the interior of the car (as far as the lens sees it). However the inside surface of the glass also reflect the external scene, which is reflected again by the external surface, and there isn't much to be done about that; the greater the angle the brighter is this reflection relative to the scene. This effect is quite noticeable on thick glass mirrors, which is the reason for using front-surface coated mirrors in optical systems.
These effects will all be present, but may or may not become intrusive.
On the other matter, strain in transparent objects can be seen using polarised light and you may have noticed patches of colour or shade in glass when looking through polarized sun glasses. This is very obvious when looking through toughened glass windshields (the sort that break into crystals in accidents) but much less so with laminated glass windshields (which slice you up when you pass through). Just something that can be a problem using a polar filter on your camera.
Of course there are simple rigs for mounting cameras external to vehicles (on door, hood), but this probably isn't something you want to do. Might be an excuse to buy a convertible!
http://www.camzilla.com.au/shop/Camzilla[/link]
http://www.stickypod.com/stickypod[/link]

Wow, really great stuff, was waiting with holding breath for the 180 on the corners!!!

Anthony

Most anything I could offer has already been covered better than I could by Serena.
I do have quite a collection of Stickypod camera mounts including their latest cheaper two sucker cradle that I've tried with our HC5. It works OK at damping vibration or depending on seemingly random factors it can make it worse and you sure cannot pan the camera. The other mounts are good value for mounting the camera outside the car for the more dramatic shots but doing that on a road trip would probably spoil the trip too much. If you're not careful getting those suckers unstuck can be quite a struggle.

One thing I've wondered about shooting through the windshield is using a sunshade on the outside of the windscreen. I haven't seen those kind of after market sunshades in decades. Does anyone remember them, they were made of perforated metal to let the wind through while blocking to sun to some extent. Probably with the modern windscreens they'd be mostly useless anyway.

Bob.

One thing I've wondered about shooting through the windshield is using a sunshade on the outside of the windscreen. I haven't seen those kind of after market sunshades in decades. Does anyone remember them, they were made of perforated metal to let the wind through while blocking to sun to some extent.

Yeah, I remember them ... mostly on trucks ... sort of the equivalent of a baseball cap visor for the windshield.

Bob, good point. Dirt and defects are illuminated by any incident light, but you don't want another giant source independently lighting them up. I like the idea of mounting the camera above the windscreen of a convertible; perhaps a Mercedes Coupe.

I could use this car--it has a removable top. I've actually considered building a mount for it.

[IMG=http://i3.photobucket.com/albums/y91/wwaag76/vette.jpg]

Only problem--my wife refuses to ride in it with me.----one of life's little disappointments.

wwaag

1978? Looks just the shot. And, you can't have everything!

Any thought to recording in front of the windshield instead of through it? A product like Digital Juice's Low Rider will strap to your car & your camera and provide a cushion to help even out the small bumps. Obviously you'd absolutely want one or more filters on the front to protect your lens from bug or rock smacks.

Advantages: crystal clear video, no reflections, possibly less road jitter in video due to cushion
Disadvantages: no rain protection, no passenger audio (if that's what you want), no way to pan the camera, slight potential for camera damage

Brian

"Only problem--my wife refuses to ride in it with me"

Then you need to get something like this:




Of course then the source of marital discord will be over who gets to drive the car and who gets to drive the camera :)

My best effort at shooting from a vehicle was running a reel of 16mm at 4fps through a camera on a tripod in the back of a ute (pickup truck) down a freeway in the golden hour before sunrise. I now know why it is called the "golden hour", I was as cold as a brass monkey :(


Bob.

Now that's impressive. Mount the camera as close to the center of the car for the minimum roll/bounce of the cars suspension. Make sure the inside of the windshield is squeeky clean with no scum. The Corvette looks more like a 1980 to me.
JJK

The Russian Arm demo is amazing--so that's how they do it. Looks like an exhilarating job.

The vette is a 1979.

Keeping the windshield "squeaky clean" is virtually impossible on a road trip--between bugs, ocean mist, rain, etc. You can't stop each time and the windshield washer is only partially effective. But again, this is only for "fun" so I guess, in the end, it really doesn't matter.

Thanks for all the comments and suggestions.

wwaag

+ 1 on the convertible idea if you have a driver....I shot the following (starting at around 00:01:15) with a tripod straddling me and a monitor rigged to the tripod at eye level.
With the camera just above the windshield I was able to get 360 degree pans...just take plenty of lens cleaner with you!

http://vimeo.com/14489146]