Friday, Mar 05, 2004 at 23:35
David, here is a reply gave to a similar question, posted a while back ..some things to consider. - cost - you would be looking at about $200 - $300 for a CAMERA that would do the job, a Black and white "board CAMERA" or tube CAMERA would suffice. ( can get color but more $$) these are 12 Volt D.C CAMERAs so no need for special power supply.
As for monitors - the smallest most suitable would be a Liquid Crystal Display, (LCD) or TFT screen ( same thing, TFT refers to latest technology Thin Film Transistor). They come in a range of sizes from about 4 inches up. and are relatively flat, and also run from a 12 Volt D.C. supply. cost is between 250 - 400 $$( i think ??- haven't had to buy one out of my own money,)then a simple 75 ohn co-axial video lead between CAMERA and display and away you go.
You need to carefully consider the lens size of the CAMERA, as this will be the determining factor as to whether you archieve what you want - you need to ask yourself " what do i need to see". - a broad picture that has a wide " field of VIEW" ( about a 3.6mm or 4.2 mm lens) will give you a good shot of objects in the immediate vicinity, great for reversing, cars very close, have a VIEW angle of about 60 to 75 degrees.
a tighter shot, say 6 - 10 mm, will give you cars about 20 to 30 meters behind, but reduces FOV to about 30 to 45 degrees.
The other thing to consider, if used at night, any car headlight, even if quite a fair way away will "flare " the CAMERA out, as most of these sort of CAMERAs are "auto iris" and let in heaps of light, when dark, but unable to tell if there is a
bright light in the distance... If that makes sense? - you would just see a white screen if a car was behind you at night.
You need to go to Jaycar/dick smith etc, get them to plug in a couple of different lens variations, and see what you can see.
Personally I dont think think REAR looking CCTV is a good idea for Caravanners if it is just for seeing cars behind you, whilst on the highway. I dont think a CAMERA will give you what you want.. These CAMERAs offer no real " depth perception" and when objects are futher away, it is difficult to tell there speed etc. They are fixed focal lenth, and objects too far away will be out of focus( as will objects too close). We sometimes forget our eyes have greater than 180 degree Field of VIEW, approximately 120mm to infinite auto focus, stereo depth perception (3D) and 5 to about 200 lux light variance tolerance. (pretty good aren't we!!)
If the CAMERA is for reversing safety, i.e, to avoid touch
parking, children, animals, then yes, great idea, go for a very wide FOV.
Another simple
test to do to "see what you can see" is to get a piece of paper/thin cardboard, A4 size,, roll it in cone, so that one end is about 10mm hole, and the sides are the above mentioned angles to the hole ( 45 - 80 dergrees. Now stand behind your van, look through your cone and this is the approximate VIEW you get, depending on which angle you chose. Remember, widest FOV available is about 80 degrees. ( 3.6mm lens.0
Cant see much can you.....
Best of luck, pls let me know if you need any further info,
Jarrod.
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Follow Up By: bayvista - Saturday, Mar 06, 2004 at 13:03
Saturday, Mar 06, 2004 at 13:03
Thanks Jarrod, and to everyone who replied.
David
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