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Thread: Does any scanner have a 3 exposure HDR scan option?

  1. #21

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    Re: Does any scanner have a 3 exposure HDR scan option?

    Ted - that looks like a fairly major loss of edge definition - which is quite likely from the multiple scan registration issues discussed upthread. Colour noise is not difficult to clean up - however it looks like your multiple scans have been severely noise reduced by the methods of blending & alignment to the point that it's taken the edge off definition

    Pere - unless you can point to exactly where Silverfast is altering the motor speeds in multiple exposure or increasing the output of the backlight, it's creating multiple exposures by manipulating the gain of the sensor - if it could boost the backlight or lengthen the actual exposure, the hardware dmax would be higher - and Silverfast explicitly does not make this claim.

  2. #22

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    Re: Does any scanner have a 3 exposure HDR scan option?

    Quote Originally Posted by interneg View Post
    Ted - that looks like a fairly major loss of edge definition - which is quite likely from the multiple scan registration issues discussed upthread. Colour noise is not difficult to clean up - however it looks like your multiple scans have been severely noise reduced by the methods of blending & alignment to the point that it's taken the edge off definition

    Pere - unless you can point to exactly where Silverfast is altering the motor speeds in multiple exposure or increasing the output of the backlight, it's creating multiple exposures by manipulating the gain of the sensor - if it could boost the backlight or lengthen the actual exposure, the hardware dmax would be higher - and Silverfast explicitly does not make this claim.
    These are stepper motors that don't have a speed, like a normal motor, they step, when told to step. When the scan line is completed they step to the next position. In order to position the sensor correctly just for one scan line, the stepper motor needs to be fairly accurate, because just to do one line requires the stepper motor to move one than once. So for one scan line you need I think 3 passes or 6 I am not exactly sure. For two passes everything doubles.

    I am just offering this an example, for 35mm kodachrome on my scanner (epson 4990) for my needs with that film I would always now use multiscan. For other films NO.

    BTW light output has nothing to do with. If you reduced the light output by 1 stop, the scan would just take longer (two times), with very little change because noise does not change that much with those kind of exposure time changes. Easy to show if have an 1 stop ND handy. If you have a brighter light that does not improve you dmax at all because you cannot overexpose a CCD as once the wells are full they are full! You are limited by how clear the film is. A brighter light will allow you to go faster IF the rest of the hardware is up to it.

  3. #23
    Alan Klein's Avatar
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    Re: Does any scanner have a 3 exposure HDR scan option?

    The proof is in the pudding. I've asked people to show their multi scan shots. (edited: None) have that showed any difference. I also checked a couple people posted with both the straight scan and the "improved" multi scan. WHen I used shadow adjustments on the normal scan, I was able to see the same results in the shadow areas as they got with so-called special scan software. Frankly, I think multi scan or other changes to the scan operation to improve scan results are a lot of hype to sell after market scan software. Basically, these changes are just post processing edits applied during the scan.

  4. #24
    Alan Klein's Avatar
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    Re: Does any scanner have a 3 exposure HDR scan option?

    Quote Originally Posted by Pere Casals View Post
    V700 does not include Multi-Exposure in the bundled software, so obviously you could see no gain with multi-pass.





    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.
    Let's assume you can get more shadow details slowing down one of two scans. How do you line up the two passes afterwards if the stepper doesn;t allow that?

  5. #25

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    Re: Does any scanner have a 3 exposure HDR scan option?

    Pere, if what you are saying is what Silverfast does, they'd be able to claim a DMax improvement. They don't, so the exposure change has to come from elsewhere in the system - boosting the sensor gain is much more readily done than anything else.

    As for boosting the light intensity, if you have a really dense/ underexposed transparency, the wells are not going to fill as fully as they could if more light was pumped through the object, which is going to give cleaner results than cranking up the gain.

  6. #26

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    Re: Does any scanner have a 3 exposure HDR scan option?

    Dmax has nothing to do with how bright the light or how sensitive your sensor is, you can have a very bright light and very very sensitive sensor but poor Dmax.

  7. #27
    Peter De Smidt's Avatar
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    Re: Does any scanner have a 3 exposure HDR scan option?

    "Nothing"? Don't you have to have enough light moving through the film to give a good reading on the sensor? Sure, you can prolong exposure to get more light, but don't sensors have reciprocity? So if one has dense film, doesn't having more light, up to a certain point, allow better scans through the dense areas? I expect that sensors have set dynamic ranges, and as long as one has enough light so that the darkest area fall within the sensors levels of good tonal differentiation, i.e. the straightish line area of it's response, then it's maximum dynamic range is set by the sensor characteristics. But if the film, when illuminated enough to get good highlight seperation, requires a bigger range than the sensor can handle, then isn't the only choices to either write off that are of the film, or take another scan, ideally without moving the system, and changing exposure to bring the trouble area withing the sensor's range, and then combining the two scans?

    With digital camera scanners, at least, doing this leads to better separation throughout the tonal scale of very high dynamic range film, as tested with a Stouffer test scale.

    Changing topics, but I'm in the process of finishing a new scanner optimized for 8x10s. If I get off the darned forum, I should be able to complete it today.
    "Poverty is the biggest cause of poverty." Rutger Bregman

  8. #28

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    Re: Does any scanner have a 3 exposure HDR scan option?

    Quote Originally Posted by Peter De Smidt View Post
    "Nothing"? Don't you have to have enough light moving through the film to give a good reading on the sensor? Sure, you can prolong exposure to get more light, but don't sensors have reciprocity?
    Sure you have to have an exposure time that allows for enough photons to be collected to create a measurable voltage, that will register on the first stage of the A/D convertor. The longer you wait to collect those photons, the more you are effected by electrical noise etc. Loss of charge while you wait is probably a factor. So your error rate just goes up.

    But if that exposure time is reasonable then yes in this context then the answer is YES NOTHING!

  9. #29

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    Re: Does any scanner have a 3 exposure HDR scan option?

    Quote Originally Posted by interneg View Post
    Pere, if what you are saying is what Silverfast does, they'd be able to claim a DMax improvement.
    And they do !! from 3.1D to almost 3.4D

    Click image for larger version. 

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    https://www.silverfast.com/highlight...posure/es.html


    The 3.4D (of the V700 with multiexposure) is way better than what the LS-9000 does without multiexposure...


    and the LS-9000 with multiexposure reaches supreme levels !!!

  10. #30

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    Re: Does any scanner have a 3 exposure HDR scan option?

    Quote Originally Posted by Pere Casals View Post
    And they do !! from 3.1D to almost 3.4D

    Click image for larger version. 

Name:	dmax.jpg 
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    https://www.silverfast.com/highlight...posure/es.html


    The 3.4D (of the V700 with multiexposure) is way better than what the LS-9000 does without multiexposure...


    and the LS-9000 with multiexposure reaches supreme levels !!!
    Effectively they're claiming a signal to noise improvement of about 1 stop - at the cost of apparently worse sharpness (you can even see this in their demonstration image - much like Ted's). Having thought about this over the last few hours, I'm still very strongly suspecting that there's no alterations to the drive mechanism or light, but two levels of image gain are blended on some specific basis & at least one is subjected to fairly vigorous de-noising or even outright blurring. In other words, something quite possibly not a million miles off the frequency separation techniques used in retouching. And it's all fairly pointless in an era when digital sensors can be used as scanners with potentially 13-14 clean stops of dynamic range in a single shot - and more to the point, how many badly underexposed transparencies are you trying to dig detail out of?

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