[sane-devel] Epson gt-8000 transparency experiment

Karl Heinz Kremer khk@khk.net
Fri, 28 Nov 2003 08:55:34 -0500

A "real" TPU is just a lamp behind some ground glass (or translucent 
plastic), so
there is not "projection" involved: The sensor scans the illuminat4ed 
negative or slide

Have you checked out the link to the message from the guy who is using a
lightbox on his Perfection 1200? He had some instructions about how to
disable the 1200 TPU. The GT-8000 should be similar.

... and I can assure you there is no mechanism to turn the lamp off 
without a
TPU (or a fake TPU) connected to the scanner.

Karl Heinz

On Friday, November 28, 2003, at 08:20 AM, Bart Buitinga wrote:

> Hello again,
> It's going to be some retro demonstration if this goes to work. Thanks
> for all your replies.
> After some fiddling with the configuration files I found the number 
> that
> defines "Blindfarbe" (shines just one of the three monochrome tubes in
> the gt-8000's sensor) for BW modes can be set 0 for none or 1, 2, 3 for
> R, G, an B. Unfortunately -1 an 4 both default to none. If there's no
> known way to override the hardware detection I think I'll just add a
> switch in the internal power cable to the tubes to get them off, also
> because the autodetection of accessories, as it differs between the
> document feeder and the TPU is beyond just shortcircuiting and of 
> course
> I wouldn't want to risk this splendid device that the previous owner
> must have thrown away after obtaining a new pc with ECP or similar.
> I've been trying some combinations without a projection screen, but I
> think the sensor would demand a strictly parallel bundle for that to
> work. (That is of course possible, but would take a lens the size of 
> the
> print.)
> Just hoovering the enlarger over the scanner only results in a light
> spot at the position of the enlargers lens
> Considering the amount of light: I think a projector would be overdone
> if theres no need to overpower the scanner tube or false light. These
> old enlargers have relatively strong lamps because in the 
> pre-multigrade
> days high grade photo paper was not too sensitive.
> But if the Opemus lets down, I also have a Krokus 3 with a condensor
> extension that throws all the 100 watt light through a 35 mm window
> instead of its usual 6x9 cm, about 3 times more powerful
> (And also: It would then help to scan on less than a4 format... Also it
> has the same lens entrance as my Praktica, so it may be easy to use it
> with a large diameter telelens to get an up to 60 mm wide parallel
> bundle... Well allright, I know what I'll do this afternoon)
> But if someone around actually has a TPU, I would be very interested
> what kind of projection (screen or parallel) it uses.
> Bart Buitinga
> Martin Collins wrote:
> > On Thu, 27 Nov 2003 21:02:43 +0100
> > Bart Buitinga <bartbuitinga@xs4all.nl> wrote:
> >
> >
> >>It occurred to me that if it is possible to project a negative on
> >>the scanners glass pane using a slide accessory, it might also work
> >>to use a photo magnifier (I mean the thing used to print in a (B&W)
> >>darkroom, an Opemus 11 to be precise)
> >>
> >
> > An enlarger. You might also use a projector.
> >
> >
> >>with some kind of half transparent projection surface,
> >>
> >
> > It might work better without a screen, just project the image 
> straight
> > into the sensor.
> >
> >
> >>just if I would succeed in scanning with the lights off.
> >>
> >
> > Right, you would need to turn the lamp off. Although, if you didn't
> > use a screen the lamps may not matter.
> >
> >
> >>I guess that normally the scanner would notice a device connected to
> >>the 15 pin entrance on the rear, and maybe it would just be a matter
> >>of shortcircuiting some of its contacts, but maybe there is a trick
> >>to do it with one of the ini's that twain32 (win95) uses. (In the
> >>latter case I hope there's a similar linux option or continue my
> >>quest elsewhere)
> >>
> >
> > I don't know if the sane epson backend can directly control the lamp,
> > I know the mustek one cannot. So you need to fake the scanner into
> > thinking it has a transparency adapter connected. That 15 pin
> > connector probably has 24V on some of its pins so don't go shorting
> > any of them unless you know what they connect to. If you don't have a
> > TPA so can't sniff its protocol you could open up your scanner and
> > disconnect the lamps.
> >
> > I would try it with the lamps on and no screen first, see what you
> > get. Please tell us the results of your experiments.
> >
> > Martin
> >
> >
> -- 
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