12mm 1/2.5in lens on an IR camera Qs

[vas]

hello all,

ordering a load of cheap stuff off a couple of ebay stores somewhere in China/Malaysia. Among the things I'm after is one or two e/r IR cameras to hook up to the Garmin plotter.

I came across this one: http://www.ebay.co.uk/itm/142224332036?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
which shows 12mm 1/2.5in (I think at least!) 3MP IR CCTV on the lens.
Q, would anyone know how wideangle this thing is, 50-60-70degrees?

Second Q, can I simply cut the bnc and solder an rca in there? Garmin takes rca input. Mind I'll have to patch it up to a 5m length of decent co-ax wire as plotter is a good distance from the installation point.

Plan to fit it at the back of the e/r facing fwd so that it can pick any leaks or nasties on the engines and also show the bilge and water intakes.

cheers

V.

 

[jimmy_the_builder]

If 12mm in this context means the same as 12mm for a normal cctv lens, then this won't be at all appropriate for an engine room installation. I would have thought you'd want wide angle, which is 3.6mm or 2.9mm. 12mm is very narrow.

 

[vas]

hm,

assuming 1/2.5in is the CCD size which is 10.1mm (diagonal???) and 12mm is the focal length of the lens, that's equivalent to a 50mm lens on a 135mm camera, which is plain normal, as you say useless.

J seems that the standard on CCD sizes for cctv lenses is 1/3inch this is slightly larger...
So an analogy would mean that a 4mm 1/2.5in lens would be around 90degrees, v.wide angle

anyway, looks like this one is better

http://www.ebay.co.uk/itm/3-6mm-Len...598888?hash=item211d5dabe8:g:Yn4AAOSwopRYY9Of

cheers

V.

 

[henryf]

A few points.

As has been mentioned already 12mm is too narrow angle for your application. The norm for cheap & nasty cameras is 3.6mm which gives an angle of view of around 75 degrees.

Be aware that the wider the angle of view the more the pixels spread apart and the less detail is captured - the image rapidly deteriorates as you move away from the camera.

It's a standard definition camera, not 3 megapixel which is good because your plotter wouldn't display a genuine high definition camera, they use different technology.

I wouldn't be cutting any wires, just use a BNC to phono (rca) adaptor.

I'm not sure you will get sufficient detail to achieve your objectives but give it a whirl.

Vas - I think you will find 12mm is narrower than a 50mm prime lens on a 35mm camera. With 1/3 inch CCD cameras 2.8mm gives around 90 degree angle of view but to repeat myself that also means your are spreading your pixels apart as you move away from the camera. Standard CCTV only has about 0.4 megapixels versus probably 12 megapixels on your digital camera.

Henry

 

[vas]

A few points.

As has been mentioned already 12mm is too narrow angle for your application. The norm for cheap & nasty cameras is 3.6mm which gives an angle of view of around 75 degrees.

Be aware that the wider the angle of view the more the pixels spread apart and the less detail is captured - the image rapidly deteriorates as you move away from the camera.

It's a standard definition camera, not 3 megapixel which is good because your plotter wouldn't display a genuine high definition camera, they use different technology.

I wouldn't be cutting any wires, just use a BNC to phono (rca) adaptor.

I'm not sure you will get sufficient detail to achieve your objectives but give it a whirl.

Vas - I think you will find 12mm is narrower than a 50mm prime lens on a 35mm camera. With 1/3 inch CCD cameras 2.8mm gives around 90 degree angle of view but to repeat myself that also means your are spreading your pixels apart as you move away from the camera. Standard CCTV only has about 0.4 megapixels versus probably 12 megapixels on your digital camera.

Henry

thanks Henry,

tbh it's all going to be just for a laugh at that price (and to check if IR can actually be used for anything else useful) as access to e/r on my boat is dead easy from the lazarette. No need to shift carpets, undo tables etc, just open the hatch go down 4 steps and through the lazarette to e/r door have a look, or crawl in. So it's not critical.
Plotter is 800X600 iirc so yes, HD isn't necessary. I understand the too wide too coarse an image to make anything out of it (other than a fire or smoke from a ruptured exhaust hose) so meant as a toy/cheap check on the way that all's fine. Maybe even add the odd coloured table tennis ball on the engine strainers to make sure water is going through (although I could also look over the transom for that...)
Point taken, BNC->RCA it is then

cheers

V.