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Dino Saga 080727 _ Shooting Glass Some More

Discussion in 'Corbani's Corner' started by John Corbani, Jul 27, 2008.

  1. John Corbani

    John Corbani Formula 3
    Honorary Owner

    May 5, 2005
    1,153
    Santa Barbara, CA
    Full Name:
    John Corbani
    #1 John Corbani, Jul 27, 2008
    Last edited by a moderator: Sep 7, 2017
    Dino Saga 080727 _ Shooting Glass Some More

    Just headlight glass this week. If you can do this, you can do most anything with glass. You have the curved front glass, the silvered back glass, the filaments, and finally, the shield just in front of the filaments. The front glass has manufacturer’s info and dimples, ridges, etc. to spread the light slightly. It is a diffuser and shaper of the beam and a protector of all inside the headlight. The rear silvered mirror reflects the filament’s light and focuses it into a roughly parallel beam. The mirror can only reflect the light headed toward it which is the light headed to the rear. The filament’s light going forward and up is blocked by a shield. Forward and down is let go directly through the front glass. Less than 50% of the filament’s light goes forward in a beam from the rear reflector. But that is pretty good for auto head lamps.

    When shooting this mess, the critical words, numbers and marks are usually molded into the inside of the front glass. The parabolic mirror behind these marks tries to add light where you least want it in a photo. The ambient light is reflected and where the light comes out appears to move with the position of the camera. You can sometimes see a distorted and inverted version of the objects in front of the lamp assembly. If you want clarity, you usually want to have either light or dark as a background for the marks.

    If you want a light background, you want the light coming toward the camera in generally parallel rays. This means the light source relatively far away, coming in through a section of the lens, bouncing off the mirror and back through the lens. This back lights the mark and the mark will scatter the light in all directions. The mark will be dark on a light background. Don’t even think of using flash for these shots.

    If you want a dark background, take a piece of black paper, cut a hole the size of the mark, and tape the paper to the lens. Light can only get into the mirror around the mark and is unlikely to come out the way it went in. Side illumination of the lens then brings the mark out as light on a dark background.

    Distance from the camera to the glass will make a difference. Closer will make it easier to get a large image. Farther away is easier to light and focus. If you can zoom in and still focus, that is good. If not, this is an area where lots of camera pixels helps. Get the image as large as you can and then crop it in an editor later. If you are just trying to get something for posting on the internet, 800 x 600 will usually work fine. A 6 Mpixel camera has 2800 pixels across so you have a lot of room to crop. Whatever you do, have the marks in focus when posted. Out of focus pictures are everyone’s waste of time.

    Practice a little before you have to do a shot in anger. You will learn a lot and the pictures that have to be right will make your point. Both of the headlights in the pictures were used and chipped on my Dino. The GEs are still in it. The one Marchal is the good one. The other got a cracked front lens and is not replaceable. Sealed beams are. I can’t see much difference in the amount of light on the road. Neither is very bright. Enjoy.

    John
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  3. Crawler

    Crawler F1 Rookie

    Jul 2, 2006
    4,995
    Wow! Great detail in those close-ups. I almost want to back the car out of the garage and give it a try. My car has Carello H4 lights that were installed when my father moved it from the UK to Switzerland 30 years ago (RHD lights point the wrong way). Low beams aren't much at all, but the high beams are decent.
     
  4. anton

    anton Karting

    May 8, 2004
    106
    On some of the European lites the bulb holder has 2 positions to allow dipping to right or left. Take a look.
    Anton
     

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