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Subject: Re: [Homebrew_PCBs] Re: PCB EDM -- further thoughts ( slightly OT )

From: lists <stuart.winsor.lists@...>
Date: 2005-10-21

In article <dajm45+cqcf@...>,
curt_rxr <cwrxr@...> wrote:
> I tried to take a pic of my LPC2138 dip header board with my PHD (
> Push Here Dummy ) film camera. It is uploaded into the Photos section
> in the PCB EDM folder and is labeled Oops! You can tell why!!!

> Any advice as to digital cameras for this sort of work? What sort
> optics are needed for closeups? Is digital "zoom" worth while?

In "the old days" with simple film cameras you used to be able to buy a
"close up lens". This was an auxilliary lens that pushed on over the
existing lens and allowed the camera to focus much closer.

They were normally rated in "dioptres" which is an alternative way of
expressing the focal length of the lens.

IIRC 1 dioptre is a focal length of 1m and if the camera was focused to
infinity the effect was to produce focus at 1m, so as you focussed the
lens closer the focal point moved closer still.

The higher the dioptre number the shorter the focal length and the closer
you could get.

You can probably still get them and they will be useable with film or
digital cameras as long as you can get them the right size and have
something to push them onto.

Only a couple of years ago I bought one in a standard filter holder (58mm
screw thread) and can stick it on the front of my SLR.

Ultimately though, for close up work, you really need an SLR and with
everyone going digital, quite good quality film SLRs can be had quite
cheaply. Extension tubes and bellows can then allow image sizes on your
film or sensor which are larger than the original object.

Stuart