Starting my focus calibration of V850 using resolution target

[Steven Ruttenberg]

from Stouffers. Should be interesting. I am starting with what I had come up with by scratching an exposed negative with a razor blade and straight edge. Will see what this yields as my base. Not only for focus, but for resolving power. All files are wet scanned using Kami scan fluid and optical mylar on ANR glass from Betterscanning and the better scanning variable height holder. My determined height initially is .125mm or 3.048mm.

[Steven Ruttenberg]

Here is the initial scan. Setting is 4200dpi, scanned as a slide at 48bit RGB and outpout as a linear raw tif file. I am hesitant to mess with the focus settings as you can read the entire scale, which shows this is better than 20lpmm or 500lpi. I applied zero sharpening, no adjustments whatsoever, etc. Exported as a jpg at 100% with bicubic only (not auto, etc) Next I will try as bw negative scan 48bit rgb then output to 16bit grey. Next I will vary the scan resolution in increments of 300dpi down, then up from 4200. When I find the best setting from that, I will then adjust focus. Finally, I will then scan the Stouffer 31 step wedge at .1 increments in steps. It is the TP 4x5 31-step transparency.

If anyone would like the full size file to look at (full tif file) let me know and I will put on dropbox. It is a 435mb size file.


https://farm5.staticflickr.com/4842/45068401945_24a827a239_b.jpg (https://flic.kr/p/2bExkJR)20181120_1-T_Stouffer_Resolution_Target_4200dpi_48bitrgb_48bitrgb_gray_BW_Negative_003 (https://flic.kr/p/2bExkJR) by Steven Ruttenberg (https://www.flickr.com/photos/157376714@N08/), on Flickr

[Steven Ruttenberg]

The full size file tif and jpg look better before upload, but still you can get my point. This is a fine scanner.

[Steven Ruttenberg]

This is gonna take a while. One thing i have notices is that the slide setting looks a bit better than the b/w negative setting when scanning as 48bitrgb whether output as 16bit gray or 48bit rgb, the two versions of b/w files look identically the same, but slight worse than the slide version.

[Steven Ruttenberg]

Okay, I finished all scans from 2100dpi thru 6300dpi. Scans at each dpi were 48 bit color slide output 48 bit color, 48 bit color bw output 48 bit color, 48 bit color bw output 16 bit gray, finally 16 bit gray output 16 bit gray. Definitely gets better the higher the resolution, but need a finer resolution chart to see for sure. Also, my focus setting is good, but I need to tweak it. First I need to find the resolution that appears the best out of all of them. Then tweak at that dpi. Definitely though don't want anything below about 3600dpi more like 4000 plus. It appears that things are much better at 6300dpi for what I scanned, although 4200 looks pretty good as well which is currently my scan dpi.

Link to all of the files for those interested in looking at them. I hope the titles are not too confusing and self explanatory.

Feel free to download the files if you want to play with them if flickr will let you. I can send the full size tif file for anyone who wants to play with those.

https://www.flickr.com/photos/157376714@N08/collections/72157673732821157/

[Pere Casals]

Amazing test !!

One thing, all scans look made with the bars vertically arranged. Probably if arranged horizontally it would be noticed a lower performance, it would be interesting to also post that to see the difference.

[Ted Baker]

One thing i have notices is that the slide setting looks a bit better than the b/w negative setting when scanning as 48bitrgb whether output as 16bit gray or 48bit rgb, the two versions of b/w files look identically the same, but slight worse than the slide version.

This is an example of how contrast effects your results. The BW version is not just the pixel data of the slide upside down. i.e. it is not 1-x

I am finding it hard to interpret what you have here, other than one looks better than other :D

If your happy to make the original tif available I would like to have a go at using ImageJ to do a slanted edge MTF test. This should give a resolution at each contrast level. They need to be raw scans, or scanned as a slide with no contrast adjustment, otherwise the data doesn't make sense.

https://imagej.nih.gov/ij/plugins/se-mtf/index.html

[Steven Ruttenberg]

Possibly could be, but they are at an angle so that should pick up some effects degradation if any. Once I set focus at chosen dpi, I may do a horizontal scan at that final setting for comparison. The flip sjde is, whatever is best from this direction by default is best horizontally. So for information purposes I will do horizontal scan.

[Steven Ruttenberg]

This is an example of how contrast effects your results. The BW version is not just the pixel data of the slide upside down. i.e. it is not 1-x

I am finding it hard to interpret what you here here, other than one looks better than other :D

If the your happy to make the original tif available I would like to have a go at using ImageJ to do a slanted edge MTF test. This should give a resolution at each contrast level.

https://imagej.nih.gov/ij/plugins/se-mtf/index.html

Well, what looks better than the other is part of what I did. I am looking for what "looks" best then uzing that dpisetti g adjust focus to get best result. This wasn't intended as a resolution test per se, but a focus test. However, I am surprised at the results and how they definitely improve through 6300dpi, although, past about 4k or 5k dpi it is about quality vs resolving power with better quality at higher dpi.

I will put files into drop box today sometime and post up link. Will be interesting to see what mtf is although in the end I trust my eyes on what looks best :D.

[Bernard_L]

Kudos to the OP for doing actual tests, but scratching my head. The scanner claims resolutions of 4000+dpi and you test it with a target that maxes at 500lpi. What am I missing?
And, your focus increments, as in 2700, 3000, 3300dpi, etc... are not hardware settings; they represent the result of some software data massaging; so, even though you perform no explicit sharpening, the perceived quality is more a judgement on the quality of the hidden re-sampling software.

[Pere Casals]

The scanner claims resolutions of 4000+dpi

Bernard, EPSON specifies that V850 has 6400 dpi, in fact this is spi, samples per inch, but true optical effective dpi are 2200 to 2800 depending on the axis, 4000 is fairly out of reach for that device.

[faberryman]

Bernard, EPSON specifies that V850 has 6400 dpi, in fact this is spi, samples per inch, but true optical effective dpi are 2200 to 2800 depending on the axis, 4000 is fairly out of reach for that device.But you still have to scan at maximum specified resolution to achieve maximum actual resolution.

[Jim Andrada]

I always thought you should scan at maximun OPTICAL resolution to get - well, maximum optical resolution. Of course, according to my wife, I'm wrong about almost everything else, so maybe this is no exception...

[Steven Ruttenberg]

Kudos to the OP for doing actual tests, but scratching my head. The scanner claims resolutions of 4000+dpi and you test it with a target that maxes at 500lpi. What am I missing?
And, your focus increments, as in 2700, 3000, 3300dpi, etc... are not hardware settings; they represent the result of some software data massaging; so, even though you perform no explicit sharpening, the perceived quality is more a judgement on the quality of the hidden re-sampling software.

As stated I did not adjust focus for this test. I simply used the focus set I had previously determined. Then ran thru the different dpi settings to see how resolution was affected at this focus setting. Next I will determjne the best focus by making adjustments to the betterscanning holder.

Nothing missing, etc. And 500lpi was just what this standard was. I got it for adjusting focus. This is just a side test for giggles.

[Steven Ruttenberg]

Well,
Let's not get crazy here. I am not trying to benchmark the scanner, but it does appear that 4000 to 6300 ( only went this high. An extra100dpi won't matter) is the sweet spot with quality improving at higher dpi. This is to test and set focus at desired dpi.

I may some day get a real fancy standard and see how it does.

One interesting fact is I can plot dpi vs file storage which is useful as one can readily determine the file size for a given dpi. I can curve fit an equation that can be used with a transfer function to account for a 4x5 negative over this. Or since we know pixel count of image I can plot Tha vs file size which may be more useful without need for transfer function.

[Steven Ruttenberg]

I think I will get a fancy hi rest target. The only issue is they are all on glass and I need it to be on film at 4x5 size. If contact printed there is the question of how well the glass target resolves to the film. Ie, no loss in accuracy of targeting reproducing line pairs. Otherwise I have to devise an adapter to hold target at correct height plus since I wet mount which is my preferred method that would be a difference in using glass target only and coils skew my results for my chosen method of scanning.

[Pere Casals]

I always thought you should scan at maximun OPTICAL resolution to get - well, maximum optical resolution.

Jim, to record all image quality a lens can deliver we need a sensor that fairly outresolves the lens performace.

184663

That table shows that performace increases when scanning at higher dpi than the maximun OPTICAL resolution, to obtain best result we have to oversample.

Of course from a certain point we obtain a larger file with little or no benefit.

[Steven Ruttenberg]

What is the article that yable comes from? I would like to understand tgeir data collection methods, what targeys they use, wet or dry scan, how best focus achieved, type of holder, etc. I also want to understand the data reduction methods used to arrive at reaults. This includes all assumptions.

As a side note I find it hard to believe that a manufacturer like Epson and others would be that misleading. It may be true that it can't resolve beyond a certain number of line pairs, but effective pixel is misnomer. You can have high pixel count and crapy resolution whereas fewer oixels nd extremely high resolution.

Suffice it to say I will do my own tests. I also feel showing a verse without the chapter and book can be extremely misleading. I am not arguing for or agaonst any type of scanner or brand.

Anyway more to come omce I get focus set. Next is 31 step wedge with 0.1 step increments.

[Pere Casals]

What is the article that yable comes from?

https://archivehistory.jeksite.org/chapters/appendixc.htm

https://web.archive.org/web/20180407084122/https://archivehistory.jeksite.org/chapters/appendixc.htm


Next is 31 step wedge with 0.1 step increments.

To find the V850 limits (with multi-exposure active) you may need a 3.5D target

[mitrajoon]

Jim, to record all image quality a lens can deliver we need a sensor that fairly outresolves the lens performace.

184663

That table shows that performace increases when scanning at higher dpi than the maximun OPTICAL resolution, to obtain best result we have to oversample.

Of course from a certain point we obtain a larger file with little or no benefit.

Pere,

Sorry if this is a dumb question but: Does the Table imply that setting DPI at approximately 3200 is the most "efficient" way to maximize the resolution of one's negative for an Epson 750. i.e., most resolution for file size?

[faberryman]

Sorry if this is a dumb question but: Does the Table imply that setting DPI at approximately 3200 is the most "efficient" way to maximize the resolution of one's negative for an Epson 750. i.e., most resolution for file size?
Yes, but why sacrifice resolution for file size. We are not talking about large files to begin with. The better efficiency argument is time. It takes less time to scan at 3200 than 6400.

[Steven Ruttenberg]

True, but again what I am observing is tge higher the dpi, the clenervthe scan and greter I can enlarge file. At 3200, file was not nearly as good as at 4200 which is what I currently scan at. And this is from practical application not svience stuff. Rarely does practical emulate science and vice versa. My image of Aspens I recently posted us at my current focus setting and at 4200dpi. If we followed all the science that image would look like crap.

[Steven Ruttenberg]

Here is the link to the dropbox folder

https://www.dropbox.com/sh/smrtz36k7tbdm5x/AAAEh3t6fkaSfx9ASBB9RNuWa?dl=0

[Steven Ruttenberg]

So I compared scans and found 6300 dpi scan was best. I then tweaked focus and found I was out To high by 0.0078in or 0.198mm. Not too bad at all. Bit that small adjustment made a difference.

After adjustment, I used fingernail polish to lock fasteners in place by applying a torque stripe to fasteners and holder.

I also have been thinking that we focus too much on dpi capabilities, etc. Instead we should be focuses on how well a scanner resolves an image. If film has say 65lpm capability andbthe scanner can equal that or better, then dpi only matters as in having enough to print at desired size. While it plays a role in how well a scanner resolves, things like pixel size/pitch, etc, play a part. If scanner can do better than film at given dpi then whatever that pixel count is, it is. Using more will give better scan to a point. What I am saying I guess is who cares about effective dpi vs dpi setting, etc if you get a quality scan of your image. I am more interested in resolving power in lpm than I am in number of effective pixels v

So for me anything at or above 4200dpi scanner setting is good. 6300 will give a huge file, but there is a technique for Photoshop that you can use to keep working file small and apply everything to final full size file.

Here is pic of torque stripes.

[Pere Casals]

Pere,

Sorry if this is a dumb question but: Does the Table imply that setting DPI at approximately 3200 is the most "efficient" way to maximize the resolution of one's negative for an Epson 750. i.e., most resolution for file size?

It's matter of diminishing returns, with the V850, from 3200 you get nothing more in the vertical axis, but you can get a 20% more in the horizontal axis. Beyond 4800 you get near nothing else.

But working with an oversampled image allows a better conservation of the image quality over the edition (if computer performance vs file size allows it...). For example rotation, sharpening and downsizing algorithms may take advantage of it.

As Frank Berryman noted a problem can be the additional scanning time, more than file size.

[Steven Ruttenberg]

Here is an example of binning.

These images show the final setting for focus with Betterscanning Variable height film holder, ANR glass and wet mounted target. Final height is 0.2035 in from scan glass to top of ANR glass. Film mounted on bottom of ANR glass (side facing scan glass)

The three images are as follows
1. Full 6300dpi
2. 2x2 binning using Vuescan Tiff size reduction
3. 3x3 binning using Vuescan Tiff size reduction

Note: 2x2 results in a 50% reduction in pixel dimensions. While a 3x3 in a factor of 3 reduction in pixel dimensions.

Also of interest is the file size for 2x2 is a factor of 4 reduction and 3x3 is a factor of 9 reduction.

I did not see any loss of edge sharpness in the reductions (some loss in fine detail, may have happened. I do not know about any effects on gradients, etc that will come next; an actual image.

Also note that no sharpening was applied at anytime, only white balance was set.

Next I am going to scan a density target with a Dmax of 3.05 in 1/3 stop increments (31 total) to see how scanner does. I may get one that goes to 4.05 next, they are relatively inexpensive. I am also going to do this test for some bw film, Across 100, Tmax100 and 400, Ilford D100 and HP5-400 using my Chamonix 45H-1 and my 75mm f/4.5 Nikkor, 90 f/5.6 Scneider Super Angulon and the 210 Grandagon I may buy. Also for my digital camera 5DMKIII. Why? Why not? Plus I can see if I need to adjust my development process and even see what different developers can do. Either I have been infected with the testing bug or I a bored! :D

https://www.flickr.com/photos/157376714@N08/albums/72157673789470327

[Steven Ruttenberg]

You do lose resolution with binning but not bad though.

[faberryman]

What I am saying I guess is who cares about effective dpi vs dpi setting, etc if you get a quality scan of your image. I am more interested in resolving power in lpm than I am in number of effective pixels.
I believe the effective resolution in dpi is just a mathematical calculation based on lpm. Most testing sites use the test target.

[Steven Ruttenberg]

I agree with this statement, but so many sites and people get wrapped around the axles on "effective" pixels, etc. You should judge your scanner on the best resolution it can resolve and what dpi setting that is on your scanner. Basically, what is the line par minimum your scanner can resolve? Who cares about effective pixels. Use scanner setting that meets your requirements for resolution. As long as it can match or exceed film capability which is around 65-80 lpm, then your good to go.

For number of stops the V850 is good for?

Well, I calculate that my V850 can do max D = 2.15 based on the step wedge I used from Stouffer. This equates to 7 1/3 stop dynamic range. This is scanning in 16 bit gray scale and outputing in 16 bit gray scale. Of course now, many should come out and say I did something wrong, or don't know what I am doing, etc. I assure you, the readings are correct.

[Pere Casals]

Well, I calculate that my V850 can do max D = 2.15 based on the step wedge I used from Stouffer. This equates to 7 1/3 stop dynamic range. This is scanning in 16 bit gray scale and outputing in 16 bit gray scale. Of course now, many should come out and say I did something wrong, or don't know what I am doing, etc. I assure you, the readings are correct.

Steven, something wrong is there, V700 exceeds 3.0D. Silverfast claims than V700 is improved from 3.1D to 3.38D by using multiexposure feature: https://www.silverfast.com/highlights/multi-exposure/en.html

V850 may even perform slightly better because coatings in the lenses.

I found that consistent with my personal tests.

Check that you are manually setting the DR end points on the histogram, that you are scanning 16 bits per channel, and that you save the scan in TIFF format. If you save it in jpg or bmp you only save 8 bits.

Also mask the area around the wedge to see ultimate performance by avoiding flare.




As long as it can match or exceed film capability which is around 65-80 lpm, then your good to go.


Capability of TMX is approaching 200 lp/mm (line pairs per mm) for high contrast (1:1000) and 1/4 of that for low contrast (1:1.6), see TMX datasheet.

"Lines per mm" and "line pairs per mm" can be confused, and there is a x2 factor for the conversion.

IMHO it's better to speak in "line pairs" and noting it with lp/mm or lppmm, because these are the usual units used by lens and film manufacturers.

The V850 is not able to retrieve all Image Quality a sharp negative may potentially have, for that you may need a drum working at high dpi, or scanning strips at high res (cezanne) and joining (stitching) the strips in Ps.

One of the reasons to go to high effective dpi is portraying well the grain structure, this is mostly intersting for roll film.

[Steven Ruttenberg]

I made some adjustments, but I had to use the built in Tmax100 profile and set the CI to .8 to get 3.05 from scanner. Yes, it was set to 16bitin and 16 bit out. But, it seems bettet scanning as 48bitrgb and output 48bit rgb. I was referring to line pairs per mm and using a rough estimate I remember from some reading I did a while ago. If it is 200 line pairs per mm, that is incredible. Once I get my hi res target, I can see exactly what scanner is capable of. So far, it seems a bit easier at least to use the scanner profile for tmax than to adjust manually, the downside is you don't get a linear output I think. But I will check this out I as I continue to learn this scanner which does seem quite amazing for 1000 bucks.

[Pere Casals]

I believe the effective resolution in dpi is just a mathematical calculation based on lpm. Most testing sites use the test target.

IMHO the testing sites and reviewers use the "effective dpi" jergon because scanners are sold with dpi capability as a main commercial factor, by rating "effective dpi" vs "hardware dpi" consumers may understand better what they were buying.

Here there is a mathematic calculation for that, used by a known testing site:

https://www.filmscanner.info/en/Aufloesung.html
https://web.archive.org/web/20180425012511/https://www.filmscanner.info/en/Aufloesung.html

[Pere Casals]

If it is 200 line pairs per mm, that is incredible.

Steven, let me comment on the TMX datasheet because it has a loose wording. I had been confused with it for some time.

TMX sports (datasheet, page 8) 200 "lines per mm" at high contrast, and 63 lines per mm at low contrast, while TMY sports 50 at low contrast, "ratings according to a method similar to the one described in ISO 6328".

I think that they made a mistake in the wording because lines/mm should be line pairs.

The MTF graph that it's included is shown in cycles/mm, this is a serious wording.

The MTF graph is the serious way to show resolving power, saying what lp/mm we have at contrast extintion it's easier and also useful, but a MTF graph is what a technician wants to see.

Here you have the TMX graph:

184681

It shows that it retains 40% of Modulation Transfer ("contrast") at some 130 cycles/mmm (line pairs/mm = lp/mm = lppmm), beware because the Horizontal scale is not linear, it's logarithmic, it looks 150 but it's not linear.

So if we have 40% at some 130 LinePairs/mm then it's possible that contrast extintion is at 200 lp/mm for high contrast, because that performance cannot be for low contrast, they only show the graph that's nicer, but common pictorial situations would be ruled by a less nice graph (a lower contrast MTF, say 1:10 instead 1:1000).

But this performance is only at very high contrast that's relatively uncommon in pictorial photography, you may have that in a silhouette with a very low flare (MC + front compendium shade).

In that situation (high contrast) in a contrasty edge we have some blur because the big grains in the negative building some level of density ...and on it we have a nitid line made with the fraction of very small crystals that are only exposed with insane amounts of light.

In the TMX case this is an strong effect because of "linearity instead shoulder", showing that extremly low ISO crystals (very small) are still sensitive to exposure values in the extreme highlights. This is what digital sensors are not doing as nice.

For this reason film resolving power vary depending on contrast, and that variations depends on grain formulation, this is the relative amounts of crystals of different size and kind, I say "kind" because films may have even different kinds of emulsions overlaped, or different emulsions mixed, each with different natures and sensitizations.

(We have expose crystals to light that are developed into silver grains...)

[Ted Baker]

I made some adjustments, but I had to use the built in Tmax100 profile and set the CI to .8 to get 3.05 from scanner. Yes, it was set to 16bitin and 16 bit out. But, it seems bettet scanning as 48bitrgb and output 48bit rgb. I was referring to line pairs per mm and using a rough estimate I remember from some reading I did a while ago. If it is 200 line pairs per mm, that is incredible. Once I get my hi res target, I can see exactly what scanner is capable of. So far, it seems a bit easier at least to use the scanner profile for tmax than to adjust manually, the downside is you don't get a linear output I think. But I will check this out I as I continue to learn this scanner which does seem quite amazing for 1000 bucks.

You not going to able to make any meaningful Dmax tests if you use the negative scanning part of vuescan. Not least because you do have the formula that vuescan used to create the image. The Dmax for these units is quite high, somewhere between 3 and 4, however the amount of noise is not insignificant. (Ken Lee did raw scans in a previous thread of stouffer wedge). i.e. It usually has more than enough range for a negative.

[mitrajoon]

It's matter of diminishing returns, with the V850, from 3200 you get nothing more in the vertical axis, but you can get a 20% more in the horizontal axis. Beyond 4800 you get near nothing else.

But working with an oversampled image allows a better conservation of the image quality over the edition (if computer performance vs file size allows it...). For example rotation, sharpening and downsizing algorithms may take advantage of it.

As Frank Berryman noted a problem can be the additional scanning time, more than file size.

Thxs to both you and FB.

[Steven Ruttenberg]

You not going to able to make any meaningful Dmax tests if you use the negative scanning part of vuescan. Not least because you do have the formula that vuescan used to create the image. The Dmax for these units is quite high, somewhere between 3 and 4, however the amount of noise is not insignificant. (Ken Lee did raw scans in a previous thread of stouffer wedge). i.e. It usually has more than enough range for a negative.

I did get it to show slightly better than 3.05, but had to use the built in Tmax100 set to a CI of.8. I was abke ri know it is 3.05 because that is how dense my step cjart is and I could image that final step wirh some head room to spare.

When doing everything manual since I want a linear scan output, it seems to have trouble no matter the settings. This concerns me because maybe I am not getting as much out of negative as I should be. I am checking my ptocess to see if doing something incorrect with vuescan.

I am going to try a positive scan, but that beats the purpose of bw neg scanning and doesn't provide the required output.

[Steven Ruttenberg]

Okay,
I think I have this figured out.

1. When you make the scan of the step wedge, it will not look very pretty, Here I made zero adjustments to enhance the image before I saved it.
2. I tried three different ways of scanning and saving
a. Color slide, 48bitrgb output to 48rgb
i. Brought into photoshop and desaturated
ii. Used Colorperfect to convert the image (of note, this required the least amount of adjustment in Colorperfect. Had to tweak the "film" gamma setting a bit to a lower value (about .75 to .9, don't remember exactly, but it did need some adjustment) then minor adjustments on the other sliders
iii. Minor curves adjustment in PS

b. B/W negative, 48bitrgb, output 16bit gray
i. Brought into Photoshop then into Colorperfect (no adjustments made in Photoshop before conversion)
ii. The "film" gamma in Colorpefect required a huge change (default is 1, had to change to .380), made minor adjustments on other sliders
iii. Minor curves adjustment in PS

c. B/W negative, 16bit gray, 16bit gray
i. Brought into Photoshop then into Colorperfect (no adjustments made in Photoshop before conversion)
ii. The "film" gamma in Colorpefect required a huge change (default is 1, had to change to approximately .380), made minor adjustments on other sliders
iii. Minor curves adjustment in PS

b. B/W negative, 48bitrgb, output 48bit gray
i. Brought into Photoshop then into Colorperfect (no adjustments made in Photoshop before conversion)
ii. The "film" gamma in Colorpefect required a huge change (default is 1, had to change to .380), made minor adjustments on other sliders
iii. Minor curves adjustment in PS

I get similar results for each setting, but setting to 48bit rgb color slide and saving as 48 bit rgb and then desaturating in PS prior to going into Colorperfect appeared to provide the cleanest file, that required the least amount of adjustments. This suggests, (I say suggests, not requires) that there may be benefit to scanning bw negatives as a color transparency and then desaturating before converions to bw when using Colorperfect. There are various other options one could use for sure, but the initial conversion from negative to positive is the most important step as we all know. The advantage I see of using color transparency for scan setting is that it is scanning and recording the negative exactly as we see it, no intermediate steps to scan and create the negative.

However, whatever is ones preferred method, if it works, then stick with it.

My next step will be to apply this same 4 settings on an actual image and see what i get.

Note, when using the color transparency option, I did not assign any preset film recipes to it. So, it should be a linear raw tif file. It certainly behaves that way however, I do not have a means to actually check the saved file to see if it is truly a linear scan, but it did not seem to matter and it does give the cleanest file.

As you can see from the images, the scanner does have better than 3.05D (which is the densest the step wedge I have goes. There is a bit more that could be shown if I had a larger step wedge range. Next time.

For now, I think I understand my scanner and the basics it needs to be used with. I also seem to have similar PS curve settings for the entire image that appear similar to the "film" curves. Whether or not this means anything I do not know. In the end, as long as you are producing the images with the details you want, it doesn't matter how you get there as long as you get there

https://www.flickr.com/photos/157376714@N08/albums/72157698054054940

One item I noticed in these target scans, is a reflection I think, this might have been from scanning during the day. I have decided that when I scan from now on to cover the scanner with a towel to block any stray light either from a window or from the overhead lights in my office. It doesn't put out any heat so to speak so it is not an issue. Plus it will keep the reflections away due to stray light. Not going to redo the targets though, the stray light did not affect the scan results and I do stand by them.

Another item I noticed, and I think Ken Lee tried to explain to me, but it didn't click right away is that whether or not you are scanning with input as slide or bw (I use slide and 48 bit as you get all three channels and can choose the one you want in PS if you want or just convert all channels to 16 bit gray. Doesn't seem to affect the linearity of the file.), if you set the bit depth to 16 bit gray, you can either let Vuescan choose which color channel to use or you can choose it yourself. I would make prescans for each channel and small output files and see which gives best result then make final scan using that color channel.

Another item I am learning now, is to make several smallish scans (again, I use 48 bit in and out as color slide) and vary the red, green and blue analog gains. It seems to make some difference, although I could be wrong and then choose the setting you like best. Right now, I vary all three equally.