Scanner light sources- LED versus Cold cathode

Started 2 months ago | Discussions
davesurrey Senior Member • Posts: 1,640
Scanner light sources- LED versus Cold cathode

Sorry for another scanner question but...

Does anyone known if the LED light source of the Epson V800/850 makes any noticeable difference from the Cold Cathode source of the V700/750. Apart that is from the much faster "warm up" time.

Or to put it another way which has an emitted spectrum that will be more suitable for scanning negative 120 and 4x5 film?

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Overrank Senior Member • Posts: 2,058
Re: Scanner light sources- LED versus Cold cathode

davesurrey wrote:

Sorry for another scanner question but...

Does anyone known if the LED light source of the Epson V800/850 makes any noticeable difference from the Cold Cathode source of the V700/750. Apart that is from the much faster "warm up" time.

Or to put it another way which has an emitted spectrum that will be more suitable for scanning negative 120 and 4x5 film?

Try “Evaluation of a LED-based flatbed document scanner for radiochromic film dosimetry in transmission mode” ( https://www.sciencedirect.com/science/article/pii/S1120179718300334 ). This is in the context of radiochromic film dosimetry but they extensive comparisons of the LED in a V800 with the CCFL in a 11000XL.

The conclusion is that “In overall, the performance of the LED document scanner is comparable to that of a cold cathode fluorescent lamp (CCFL). There are important spectral differences between LED and CCFL lamps that results in a higher sensitivity of the LED scanner in the green channel.” and that “the LED based scanner has a strong non-uniform response that must be adequately corrected for the measurement of dose distributions” but they mention that the V750 has a non-uniform response which seems to be more to do with the optics than the light source.

OP davesurrey Senior Member • Posts: 1,640
Re: Scanner light sources- LED versus Cold cathode

Thanks as ever for that reference Overrank. It’s very interesting although I had already seen it before.

I am still interested if anyone has any actual first-hand experience of comparing the scans from the two types of light sources.

There do seem to be a number of benefits to be had from LED sources (whether they be single white LEDs as in the Konica Minolta 5400ii or multiple narrow band LEDs as in some of the Nixon scanners) rather that cold cathode sources (CCFL).

It seems that LEDs:
• emit a fixed spectral output irrespective of temperature or age
which CCFL do not (even during a scan)
• need no warm up time
• have a much longer life time (should out live the scanner’s life)
• can have a wider, less spiky, spectral output (white LEDs) which
can have benefits when scanning different emulsions eg Kodachrome

But how much real life visual difference the above actually makes is still unclear to me.

However one positive outcome that came out of my research was that I’m happy I got the KM 5400ii rather than the earlier model.

 davesurrey's gear list:davesurrey's gear list
Canon PowerShot G12 Canon PowerShot SX260 HS Panasonic Lumix DMC-FZ200 Nikon Coolpix A Panasonic FZ1000 +36 more
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