Re: Color CCD sensor with support hardware wanted

From: Graham W (graham_at_his.com.puter.INVALID)
Date: 08/08/04 

Date: Sun, 8 Aug 2004 11:53:53 +0100

"Nautilus" <reply_in_newsgroup_thanks@example.com> wrote in message
news:6eKdneT1Ku-UPojcRVn-tA@comcast.com...
> On Sun, 8 Aug 2004 04:02:15 +0100, "Graham W"
> <graham@his.com.puter.INVALID> wrote:
>
> >Nautilus wrote:
> >> On Sat, 07 Aug 2004 09:53:36 GMT, "Roger Hamlett"
> >> <rogerspamignored@ttelmah.demon.co.uk> wrote:
> >>
> >>>
> >>> "Nautilus" <reply_in_newsgroup_thanks@example.com> wrote in message
> >>> news:4NmdnT_XA6EPxYncRVn-pw@comcast.com...
> >>>>
> >>>> Is there any Color CCD sensor (at least .5 inch square) available
> >>>> that's suitable for the hobbyist budget? Hopefully with some
> >>>> back-end support electronics so that I can get it to USB or 1394?
> >>>> Capture & transfer speed is of no concern.
> >>>>
> >>>> I see this Sony commercial camera with the kind of 'guts' I want:
> >>>> http://www.sony.net/Products/ISP/products/interface/DFWSX.html
> >>>> but yikes, it's the better part of $3000!
> >>>>
> >>>> Thanks...
> >>> The cheapest route, will be a standard digital camera. Something
> >>> like the Canon 300D, since it supports removable lenses, will be the
> >>> easiest to connct to whatever you want. This sort of camera, sells
> >>> often for less than the bare CCD can be purchased in limited
> >>> quantities, so will allways undercut units like 'commercial'
> >>> cameras, which are made for a small market. The CCD you want is
> >>> relatively large (CCD sizes are normally quoted as the diagonal of
> >>> the chip itself, so a 'half inch' CCD, will typically only be about
> >>> 9 * 7mm). For smaller CCD's, there are routes like wiring a larger
> >>> chip, onto a webcam board, but for a unit this large, thge total
> >>> cost of this, still runs to about as much as the Canon camera...
> >>>
> >>> Best Wishes
> >>>
> >>>
> >>
> >> Thanks, but darn, that puts the kaibash on my plan. Still too pricey
> >> and since that's a diagonal measurement, it'd still be a bit too
> >> small. I was hoping to scan 16mm film frames in direct contact with
> >> the sensor, but I'd probably need about 13mm (~1/2") wide sensor
area.
> >> Looks like I'll need to use optics, and I think my bro's MiniDV cam
> >> has a higher-than-video-res still capture mode... that gives me
> >> another idea to play with.
> >
> >Even if a large CCD were affordable, direct contact is not the way
> >to do it. The cover slip on the CCD has a discrete thickness and
> >then the active surface has coloured dots on it for the RGB pixels.
> >
> >You'll have to use optics but then a webcam has sufficient resolution
> >these days and also has a focusable lens. Its software will permit
> >the saving to disc of the files.
>
> About the discrete thickness I think you mean that the image has to be
> focused on the sensor, behind the cover slip & colored dot layers. I
> did wonder about that.

Yes, indeed. Any image formed on a plane other than the active
surface of the CCD will not be in focus.

> What particular webcam products do you think I should look at?
> There's sooo many junk ones out there that google doesn't help.

The Philips ToUCam Pro II is well regarded in astronomy circles.
It isn't the cheapest at around $100 but has a lot of support around
the 'net and in the QCUIAG group on Yahoo!

> I'll need additional optics, right? I don't expect the usual webcam
> will focus on a 16mm backlit object at full frame.

No, the existing lens will focus down to extremely close and I have
no doubt that you'll be able to get acceptable images for TV use.
I have focused an image of a UK five pence piece (18mm dia)
full screen on a TV monitor using a tiny security camera and its
standard screw-thread lens . I shot a photo of the screen on my
Olympus C3000z which I could make available later if there's
some interest.

You may need to be careful that you don't over illuminate the chip.
but a layer or three of matt white plastic diffuser should do it.

> Is there an easy
> solution here that I'm missing?

Webcam!

HTH 

--
Graham W   http://www.gcw.org.uk/ PGM-FI page updated, Graphics Tutorial
WIMBORNE   http://www.wessex-astro-society.freeserve.co.uk/ Wessex
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