digital gel documentation

Christopher B. Yohn cyohn at
Tue Mar 7 12:38:17 EST 1995

In article <1995Mar6.132200 at>, rdunbar at wrote:

> We need to set up a Mac-based gel documentation system.  We figure that a
> high-res monochrome CCD camera with appropriate filters, feeding into a
> frame-grabber like the Scion LG-3, with either Photoshop or NIH-Image
> should provide a user-friendly alternative to the (expensive) commercial
> packages.  Does anyone have any experience of setting up such a system?  Our
> early experiments show us that the filters are critical, to prevent the camera
> being swamped by light from the transilluminator,

This is true.  After some experimentation, we solved the problem with a
band pass filter from Omega Optical [(802)254-2690].  By perusing the
NIH-Image mailing list archives, I learned that their filters, while a bit
more expensive, are better at blocking at higher wavelengths (i.e. >1000
nm).  CCD cameras are very sensitive in this range and therefore this
blocking is necessary.  For EtBr fluorescence, we got a band pass filter
centered at 585 nm +/- 35 nm for $360.  That includes mounting it in a
screw-on filter holder that fits directly on our camera.  We just ordered
and received this filter within the last week or two.  So far it seems to
be doing the job.

>                                                 and that the Mac video system
> that's packaged with LC630s is not up to the job.  We've also yet to find a
> suitable greyscale printer - the Mitsubishi videoframe printers don't seem
> particularly Mac-compatible.  Any ideas/solutions appreciated.

We are using a Sony B/W video printer.  The key to using any of these
printers with a Mac is another video card from Scion.  They make a TV-3
card ($500) which can export an image from the active window in NIH-Image
to a video signal which can be hooked directly up to a video printer.  We
had a few problems with this board at first (A/D converter fried a couple
times), but Scion went out of their way to help us.  It now works
perfectly.  At $0.085 a print, it sure beats Polaroid prints ($1.44
each).  If you have other ?'s, feel free to contact me directly.

(BTW, no connection to either Omega or Scion)

Christopher B. Yohn  [cyohn at]
The Scripps Research Institute
Dept. of Cell Biology - MB8
La Jolla, CA  92037
Ph: (619) 554-4335
Fax: (619) 554-6188

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