Nikon Coolscan: Problem with underexposed slides

Dr Jules · Sep 27, 2021

I've been using a Nikon Coolscan 5000 with the supplied software (Nikon Scan v4.0.3) for quite a while now and have successfully scanned hundreds of slides and negatives. However, I'm now having a nightmare with a couple of underexposed slides and I'm wondering if I've inadvertently messed up some setting.

If I scan an adequately exposed slide, the preview and the scan look about the same. Here's an example of my grandmother. The preview:

The scan:

They're roughly the same. But I've also got a couple of slides (of my father) which are pretty underexposed. I can get the preview looking fairly OK by setting the Analog Gain Master to 2 but the result of the scan remains very dark - almost as if the change to the gain has been ignored. Here's the preview:

Here's the actual scan:

Does anybody know what I might be doing wrong? I'm reaching the end of my tether! Any help would be gratefully received and help that solves my problem would solicit eternal gratitude. Or something like that.

Thanks.

Kino · Sep 27, 2021

Don't use master gain. Go into curves (ganged RGB) and pick a point on the curve about 3/4 of the way toward the shoulder (top) and bow it upwards to expand the mid-tones.

Turn off any automatic exposure...

Dr Jules · Sep 27, 2021

Thanks Kino. By auto exposure, you mean this?

I'm post-processing in Lightroom, so I can fiddle with curves there - it's just that the output from the scanner / software combo is so terrible it's irrecoverable.

Why can't it look as good as the preview - that's all I want! Isn't that the point of a preview?

Kino · Sep 27, 2021

Kino · Sep 27, 2021

Well, the point of a preview is to give you an idea of what the image will look like with a typical image that is roughly in the proper exposure range.

Once you exit that range with a marginal image, AND leave auto exposure on, it does it's "Magic" by spreading the image data across the histogram according to their proprietary algorithm. Basically, it take the lowest pixel density and pegs it to "0" and the brightest to "256" for 8 bit color (or insert your bit-depth limits here).

When you have normal or near-normal images, auto exposure works just fine. Just exit and adjust the image with manual tools when a known problem image is being scanned and you' should be fine.

I prefer to use the curves settings in broad strokes for the scan and in much finer strokes later in an image editing program.

Lift the shadows out of absolute black, make sure your mid-tones are in a good range and drop the specular highlights to just below clip. Once scanned, it can be imported into Photoshop and everything brought back into line with what you want or can do. If you scan anything clipped, you can't bring it back, as you probably know...

Les Sarile · Sep 27, 2021

Dr Jules said:
I've been using a Nikon Coolscan 5000 with the supplied software (Nikon Scan v4.0.3) for quite a while now and have successfully scanned hundreds of slides and negatives. However, I'm now having a nightmare with a couple of underexposed slides and I'm wondering if I've inadvertently messed up some setting.

If I scan an adequately exposed slide, the preview and the scan look about the same. Here's an example of my grandmother. The preview:

View attachment 286419
The scan:

View attachment 286420
They're roughly the same. But I've also got a couple of slides (of my father) which are pretty underexposed. I can get the preview looking fairly OK by setting the Analog Gain Master to 2 but the result of the scan remains very dark - almost as if the change to the gain has been ignored. Here's the preview:

View attachment 286421

Here's the actual scan:

View attachment 286422

Does anybody know what I might be doing wrong? I'm reaching the end of my tether! Any help would be gratefully received and help that solves my problem would solicit eternal gratitude. Or something like that.

Thanks.

That does seem odd to me as I've never seen the result not closely matching the resulting scan in thousands of scan using Nikonscan since 2000 to present. I also use Analog Gain Master quite a bit and I still don't recall ever seeing this discrepancy..

Is "Enable post processing" enabled/selected? In my default setting, I always disable it - on in Nikonscan, not select/enable it. This is what that screen shows right below Enable Digital ICE . . .

#3 by Les DMess, on Flickr

In my flickr album, I show my normal default setting to create a setting to save (#1 - #5) and how to apply a saved settiit to seelcted frames (#6 - #13) -> https://flic.kr/s/aHsmWLJmWJ

I will try to find a very underexposed slide and see if I can replicate your settings if this doesn't correct it.

Dr Jules · Sep 28, 2021

Thanks for all your help. I've had a bit of a breakthrough. Although the slides are Kodachrome, I've set the film type to positive - that led to a marked improvement both in overall colour and exposure. Also, the preview pane matches the scan result.

Setting the master gain to 2 and the individual R, G and B ones to 1, gives me something I think I can work with in Lightroom.

(My father, early 1960s.)

Les Sarile · Sep 28, 2021

That's pretty good considering how dense Kodachrome gets being that underexposed. Does the preview match the scan now?

Dr Jules · Sep 28, 2021

Righty ho! I think I've tamed the beast. I'd overlooked "Scan Image Enhancer". With "Auto exposure for positive film" turned off (aside: does anybody know how this works in relation to "Scan Image Enhancer"?) I found that there was a massive discrepancy between the preview and the real scan for both Kodachrome and standard Positive film when SIE was turned on; the real scans were very dark. With SIE off, the scans matched the preview and were pretty good in terms of exposure.

All of this was with the defaults for Analog Gain (i.e. 0, 0, 0 and 0).

So I've been able to scan my handful of very dark positives, thanks to all your help and advice.

Talking of which, what are people's recommendations for positives / negatives where the exposure is generally good, in terms of the following:

"Auto exposure for positive film" (in Preferences).
"Scan Image Enhancer" (on Tool Palette).

Aside from those, I've generally been using

ICE (On: Normal)
ROC 0
GEM 3
DEE disabled
Multi Sample Scanning: Normal
Scan Bit Depth: 16

Ta. Julian.

MattKing · Sep 28, 2021

Dr Jules said:
So I've been able to scan my handful of very dark negatives, thanks to all your help and advice.

I'm confused.
I thought the film was Kodachrome, which would mean positives rather than negatives.

Dr Jules · Sep 28, 2021

Ooops! Sorry - corrected. Yes, they're all positives.

reddesert · Sep 28, 2021

I don't have a scanner that supports scan image enhancer and haven't used Nikon Scan in a long time. However, from reading the description, I think SIE is doing an auto contrast adjustment (and hue etc) after preview and during scanning. In the case of your problem slide, I suspect what is happening is that it is setting the contrast to accommodate the whitest levels of the white shirt, which unfortunately then puts the majority of the scene too far down the curve - too dark to deal with. Compare to the preview, which is blowing out the highlights of the white shirt but leaves the rest of the scene at a workable level.

Dr Jules · Sep 29, 2021

reddesert said:
I don't have a scanner that supports scan image enhancer and haven't used Nikon Scan in a long time. However, from reading the description, I think SIE is doing an auto contrast adjustment (and hue etc) after preview and during scanning. In the case of your problem slide, I suspect what is happening is that it is setting the contrast to accommodate the whitest levels of the white shirt, which unfortunately then puts the majority of the scene too far down the curve - too dark to deal with. Compare to the preview, which is blowing out the highlights of the white shirt but leaves the rest of the scene at a workable level.

I think you're absolutely right - thanks for the explanation. There's also a case of RTFM; "... note this may not have the desired effect on dark images." So I think I'll usually have it on but turn it off for dark images.

Nikon Coolscan: Problem with underexposed slides

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