Does any scanner have a 3 exposure HDR scan option?

[Alan Klein]

Vuescan with epson V series and 4990 all have 2 exposure HDR options, it is just called something different :-)

It is only needed with transparency, its a simple and very effective improvement for almost nothing for kodachrome at least if you already have the software. (scan takes longer). Two passes is all that is needed three passes isn't really necessary. Not really required for negs if the exposure is set appropriately.

I have an Epson V600. I know of no way to change the scan to change the light output which is currently set on maximum anyways. So how would two scans work to improve seeing more data in the shadow areas?

[Peter De Smidt]

I don't know that scanner, but some work by having a longer exposure time for the second sample, but to repeat: multiple exposure is usually unnecessary. It's better to use a device that can capture the required data in one sample. If that's not an option, then it's better to have a system that makes multiple samples, either varying light intensity or exposure time, at each sample location before moving on. Multi-pass systems usually lead to a loss of detail, as the passes don't line up perfectly.

[Ted Baker]

multiple exposure is usually unnecessary.

Peter,

I found for 35mm kodachrome, with exposures all over the place (often 1 stop under or more) using the "2 exposure HDR scan option" was a no brainer, the S/N ratio in shadow areas was improved, I never bothered to check any drop in resolution but the Signal/Noise ratio improvement is very obvious. It just looked better for virtually no additional effort. Often the same thing could be achieved by a single pass if I manually set the exposure since the highlights were also dense, but this requires a preview scan and operator to do so.

This was for the 4990, it is a pity this feature is not properly implemented so that only a single pass is required. I never use this feature for negatives, but I found it was certainly useful for underexposed kodachrome. For properly exposed 4x5 perhaps less so, I don't normally shoot transparency.

[Peter De Smidt]

Fair enough, Ted. I've only scanned about 50 Kodachromes, and there were all taken by my father. They scanned without any problem using a single exposure on a Nikon Coolscan V. In a given system, minimizing noise/tonal concerns might very well trump max detail. As usual, one should try all the options with one's system to optimize the process for one's purposes.

[interneg]

I don't know that scanner, but some work by having a longer exposure time for the second sample, but to repeat: multiple exposure is usually unnecessary. It's better to use a device that can capture the required data in one sample. If that's not an option, then it's better to have a system that makes multiple samples, either varying light intensity or exposure time, at each sample location before moving on. Multi-pass systems usually lead to a loss of detail, as the passes don't line up perfectly.

I've seen no evidence that any of the aftermarket software is able to vary the light intensity or drive speed of consumer flatbeds - and given that most of them in regular operation seem to use 2 overlapping sensor lines per colour channel of about 1200ppi resolution & attempt to interpolate/ align the whole thing together not terribly well, adding a second pass is just going to make things worse. I spent/ wasted several hours last week testing the effects of combining & aligning (in the manner oft described under various pseudo pixel-shift workaround techniques) several native 1200ppi scans from a 3xCCD sensor to get to 2400ppi to see how they'd compare with a single 2400ppi native scan. The results were interesting - the combined scan was qualitatively worse in some aspects than either native scan, yet did seem somewhat higher resolving than the 1200ppi. Interestingly, the qualitative flaws were not dissimilar from the flaws seen in consumer flatbed scans. What I think it showed me is that for optimal results, the software needs to know exactly how far the sensor has been moved shot-to-shot in order to optimise alignment - and is pushing me in the direction of cameras with built-in pixel shift systems for any further exploration in this direction. I think pixel shift has potentially more to offer than multiple exposure does- and it would not be a million miles off how a Fuji Frontier effectively operates...

[Corran]

In my tests with both a Nikon LS-8000 and Epson 700 years ago, multi-pass exposures usually resulted in poor performance and little to no gain in the shadows, even on the much superior Nikon.

[interneg]

In my tests with both a Nikon LS-8000 and Epson 700 years ago, multi-pass exposures usually resulted in poor performance and little to no gain in the shadows, even on the much superior Nikon.

That tallies with 'multi-exposure' not really adjusting the exposure & instead adjusting the gain.

[Ted Baker]

These are two crops of 35mm underexposed Kodachrome 64, nothing at all special other then sentimental value from my Epson 4990-

These are both straight scans with no operator adjustment, enlarged to 200% on 2100x3200 pixel scan so nothing special, I made no changes to the scan other a simple linear increase to bring these shadow areas up to a level slightly above what I think it should be SHOW the DIFFERENCE in NOISE.

The difference is noise is visually obvious. At normal size, most people won't notice, but it looks just cleaner. Like many things in photography maybe it add .5% to image, sometime those .5% all add up, but it is important see this all in context.

I kept these scans purely as example. It is a pity its not properly implemented in these scanners.

[Pere Casals]

In my tests with both a Nikon LS-8000 and Epson 700 years ago, multi-pass exposures usually resulted in poor performance and little to no gain in the shadows, even on the much superior Nikon.

V700 does not include Multi-Exposure in the bundled software, so obviously you could see no gain with multi-pass.

That tallies with 'multi-exposure' not really adjusting the exposure & instead adjusting the gain.

The V700 and V750 are true multi-exposure able (extrange that you are not aware), the V700 requires a Silverfast software upgrade to have it, it requires the SE Plus, instead the SE version.

I'd say that you are not aware of the great benefits of ME in the V700 with velvia very deep shadows, when I can I'll prepare a side by side: the difference is huge !!!

Single ME problem is that it is much slower.

Multi-Exposure in Silverfast is an exposure time change, not a gain change. Don't think that changing the exposure time is high technology, exposure time it's just a parameter you set in the firmware, a single value.


While an scanner can make the two exposures for a row before advancing the Epsons don't support that, so two passes are required, if film curls from illumination heat then the second pass may not match, but if one makes flat negatives then there is no problem, also the anr glass on the negatives prevents that, or ideally we can wet mount. IMHO wet mounting is always good/necessary with curled film, some find that wet mounting was much better because they pruduce curled negatives that are not in focus.

[Pere Casals]

the DIFFERENCE in NOISE.

Just the same I found.