Homemade Transparency Adaptor?

[michael_pye]

Hi,

Simple question really.I mentioned in another post I was wanting to

scan some old glass plates into my computer and was looking for a

scanner.Being that some are 10"x8" plus and my budget is about £150.I

thought I might try and make a Transparency Adaptor instead.

 

Is the Transparency Adaptor that comes with scanners just a static

light that illuminates the slide/neg? Or does it have more functiions

e.g. gets brighter when the scanner is going over the image and say

the image is under exposed?

 

My guess is it's just a light hiding behind some white perspex?

[jonathan_ratzlaff]

That is essentially the case, however in order to get good results you need a fair amount of even light. It does not need to vary in brightness. YOu also need to be able to rurn off the light for reflective materials. In theory, if the negative is not too dense, you may be bqle to use a gepe light panel as a transparency light source. It may be bright enough.

 

Anyway it would be cheap enough and cover enough space.

The only problem with flatved scanners is that they genrally do not vary the exposure time especially if you are trying to fool the scanner into thinking it is still scanning reflective material.

[cliff_rames]

I haven't tried this myself, but read in a book about photography by Ralph Evans, that it might be possible to scan negatives (and transparencies) on a flatbed by placing a mirror over the negative. Recommended was a front-surfaced mirror, in particular, a piece of polished metal. I guess the emulsion side should be up, in contact with the mirror to minimize ghosting.

 

Since the light is making two passes through the emulsion, the density is doubled. You can compensate for this with a gamma adjustment in your image editor.

 

If this works it would be nice because it is simple, inexpensive, avoids having to worry about disabling the scanner's internal light, and should not interfere with the scanner's self-calibration.

 

Regards,

Cliff Rames

[John Crowe]

I have tried the mirror idea and the white cardboard pentaprism reflector idea and neither is acceptable. The closest I came was laying a 24" fluorescent light across the flatbed scanner with a 35mm slide beneath it but the light was not even across the slide but this was effective enough to post here. I just removed that photo yesterday from my folder but I probably have a copy of it. So the main problem is getting even, fairly high intensity, light across the 10"x8" (as you say in Great Britain) surface. I was using a crappy 8 year old scanner so a current model would record the info that much better. Good luck!

[drpratik_pipalia]

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