CentreCam

I have just managed to load this program which appeared in MEW recently. Bought an ancient laptop for the purpose. Has anyone had a go in their workshop and if so, what are the findings please?

Norman

Reply to
ravensworth2674
Loading thread data ...

I've made myself a centre cam and fitted the illumination led's.

I found a few things. rather than freehand out the pocket for the camera I bored out a recess about 2mm oversize. I made the mating part so that it just touches the pcb of the camera. I then carefully cut out two stout paper rings and gled them to the inner faces so that there can be no shorts on the pcb and to provide a compliant grip.

With the led's I found it better to make a perspex ring and push fit them in rather then the aluminium ring used by the author. I also found that with careful measurement I could make the led ring flush, this gives better access and makes for easier positioning.

I have found the resistors used by the author can make the illumination a little dim at times. I am currently experimenting with fitting lower valued resistors with a variable resistor (salvaged from a mini radio) to vary the illumination.

I found it much easier to make a simple pcb, I mounted the led's properly and the resistors on the copper side. This gives better clearance.

If anyone would like the pcb design just drop me a line at penidrawltd (at) btinternet.com

Another thought that I have not experimented with is to use infra-red led's. most digital cameras are very sensitive in this spectrum (its what most night vision video cameras use) and it may cut down on glare.

I'm contemplating having a switch to go between white & Infra-red but that would mean even tighter soldering.

If and when I get time I'll let you know of any results if you are interested.

Regards

James

Reply to
JamesC

James, Many thanks for your valued comments. I'm on a Creative Lab webcam and wonder whether it is any improvement on illumination. Please keep in touch

Cheers

Norman

Reply to
ravensworth2674

There are a good many variants on the LED torch theme becoming available these days, and some are very cheap. Try searching Ebay for "LED headlamp" for some examples - some designed for use on bicycles, others are ones that you wear on your head. I got a couple of these for close-up photographic use but they would be adaptable for this kind of use also (or just as general purpose work lights in the shop).

Regards, Tony

Reply to
Tony Jeffree

Tony, I thought that these LED things were flashing things on bikes to drive my car at! And to think that I was pondering on how to fit/modify a =A33 childs microscope with a spot light bulb. Back to the drawing board- thanks

Norm

Reply to
ravensworth2674

Although it's usual to aim for uniform illumination it's really only optimum when attempting to get shadow free illumination of large area textured images. For identification of a low contrast edge, a scribed line or a centre pop it's often better to use angled asymmetric illumination

Multiple LEDs may be better for viewing some objects but it's useful to include the facility to reduce to to a single LED. I find a single strategically angled LED gives improved contrast. With single LED is there is a slight sideways bias wholly within the width of a centre pop or scribed line. This is normally neglible but can be directly observed and corrected by using a pair of LEDs 180 deg apart and switching between them.

Although the silicon sensor in the small video cameras is IR sensitive, the sensor in most of them is covered with an IR stop filter. Unless this removed IR sensitivity will be very low. However, even a single white LED will give ample brightness if fitted with the appropriate series R. White LEDs are OK at 30mA continuous rating so, with 5V supply, R could be as low as

100ohms.

Jim

Reply to
pentagrid

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.