Copying 35mm Slides With The Nikon Z7; Part III; Results Of My Initial Tests

Another early test.  One of the issues I've found.  You may not be able to see it on your monitor, but in the oval in the upper left of the image, I can see some subtle magenta/purple shades mixed in the with the blue sky.  It shouldn't be there and I'm working on why its there and how I can fix it.  I've described the issue more fully toward the end of this post.
(click to enlarge)

Recently, I purchased a Nikon Z7 camera body.  One of the main reasons I made the purchase was to copy a significant number of 35mm slides (and some negatives in several formats) from my archives.  Many of these slides are of family as well as landscapes, travel, railroads, old infrastructure, old bridges, barns and other miscellaneous subjects of which I am interested.  In part I I wrote about defining goals and clearing figuring out what it is I am trying to accomplish.  In Part II, I set out to figure out what questions I needed to ask myself and what tests needed to be conducted in order to create a process that resulted in efficiency and maximum quality. You can read Part I here and Part II here.

Before I started the actual copy process, I felt I needed to do some testing.  I thought it foolish to assume what may be the best way to accomplish this project so testing my system and adjusting my procedure and settings based upon the results was necessary.  Here are the questions I had developed and the results of my testing. 

What is the sharpest aperture of the Nikkor 60mm f/2.8 G Micro lens?  

My tests revealed this is an excellent lens—sharp from edge to edge.  From my testing, I find that f/8 and f/11 are the two apertures that appear to clearly resolve the most detail.  Either would suffice.  

Will a digital file of a slide be sharper if photographed emulsion up (focus on the emulsion itself with a reversed visual orientation) rather than photographing through the acetate base (emulsion side down and correct orientation)?

I carefully copied several test slides with emulsion side down and emulsion side up.  I looked really closely and didn't see a difference.  There may be some, but the depth of field using f/11 or f/8 with the macro lens should compensate for the tiny difference in focus planes.  From what I found with a depth of field calculator, the depth of field for this lens at at 1:1 magnification at f/11 is 4.4mm and at f/8 it is 3.1mm, both of which is more than the thickness of the film base plus emulsion.  That being the case, I will copy the slides emulsion down, which allows me to view and import them into Lightroom in their correct orientation rather than having to flip them horizontally in Lightroom at a later time.

Will the use of the camera's electronic shutter rather than the mechanical shutter have any advantage?

Nikon's latest firmware upgrade for the Z7 included an "auto" setting for selecting the type of shutter to employ.  In the past the selections were mechanical, electronic first curtain and silent (fully electronic).  I now have the camera set using "auto" as my research has found potentially a bit of "shutter shock" at shutter speeds up to about 1/250th of a second when using the mechanical shutter.  The "auto" setting will use the electronic front curtain until the exposure reaches faster than 1/250th second, which will not be an issue as the light levels are giving me exposures in the area of  1/6th of a second.    

Will a remote release be any better than using a 2-second delay after manually pressing the shutter?

In my tests, I saw no difference.  I will use the 2-second delay as that will preclude me from having to, each time I want to make an exposure, grab a remote release. Also, I may potentially catch the remote release's cable on something accidentally and pulling the camera over.  The camera also has a function that allows you to touch the LCD where you want to focus and the camera can focus only or focus and expose.  That can work with the 2-second delay but I think I'd rather precisely set my focus point by looking through the EVF putting the focus square in a location with good contrast.

Is manual focus better than autofocus?  Which is more consistent?

I found that using autofocus was very consistent and much quicker.  I could manually focus but it is much easier to autofocus as the camera focuses off the front of the sensor and not a separate focusing module as is the case using a DSLR.  One of my goals is efficiency and autofocus is much more efficient and, from my tests, even more accurate than am I manually focusing each slide!

Which focus point is best to use in the Z7?

I plan to use AF-S as there is nothing moving in this endeavor.  AF-C makes no sense.  In AF-S I tested both the "pinpoint" and "single" focus points.  The "pinpoint" focus uses contrast based auto focusing (CDAF) while the "single" focusing point uses phase detect auto focusing (PDAF).  I didn't see a real difference in accuracy with either, but CDAF is known to be more accurate than PDAF, albeit a bit slower.  Additionally, since I'm not using a "native" S-mount lens but an "F" mount lens, PDAF could have some inaccuracy if I didn't check the lens using the camera's micro focus adjustment feature.  Pinpoint it is.  


What is the white balance of the Acculight diffused light source?

After making many test shots of many different slides, it appears the most accurate setting for white balance with the Acculight light box is 4900 Kelvin.  With that setting, the digital image file will keep the color balance of each slide as is.  I tried one of the three Auto white balance setting the Z7 provides (Keep Atmosphere), and it works pretty well but some tuning needs to be done during editing whereas the 4900 kelvin setting gets it right every time.  Now, if the original slide is way off color, I may try the auto white balance on a case by case basis to see if it is better to white balance the slide in-camera as opposed later in Lightroom.  

Should I use a Kelvin temperature white balance setting in the camera after determining the color of the light from the light table or will auto white balance be more appropriate?

I answered this in the previous narrative.  I will use the 4900 Kelvin setting.

What exposure is best considering what I see on the histogram versus what I see on the camera's LCD?  What about the "expose to the right" (ETTR) method?

I've now exposed several test slides in a few ways.  In other words I've used the "Expose to the Right" (ETTR) method to maximize information in the digital file as well as just looking at the slide on the LCD and adjusting the exposure compensation dial so it looks like a well exposed scene.  I've also split the difference and exposed some with what I will call "brighter than normal" just to see if there is a difference when later editing the files.  ETTR doesn't seem to matter but adjusting my exposure to make the slide look like it was exposed as originally intended seems to work pretty well.  After all, these are slides and not scenes out in nature.  The information in the slide is finite and not like out in the landscape.

Do I need to bracket exposures in order to dig detail out of shadows (slide film has very little dynamic range as compared to digital and there "might" be some detail in shadows that initially look lost or black?)

I tested a couple of really high contrast Kodachrome slides in which there was underexposed black areas.  Bracketing brought out just a tiny bit more from the slide's emulsion but with it came issues with film grain and false colors.  I don't think there is enough that can be gained to mess with bracketing.  In general, if detail is lost in the slide, I don't think I can recover much if any.  If I can recover some, it really isn't something that looks like I want to see it.  I'll stick with one exposure.  If this were a project to forensically recover evidence, then I would bracket. 

Which Nikon Picture Control (Film Simulation for you Fujifilm users) is most appropriate in order to best judge highlight and shadow detail and get the most accurate histogram so I don't unnecessarily lose shadow or highlight detail?

Nikon's and others' recommendation, from the research I've done, is to use the Flat Picture Control (camera profile).  That, according to those who opined about it, will give the best idea of what the digital file will look like as well as the most accurate histogram.  I tried Flat, Adobe Color and Landscape profiles.  The Flat Picture Control gives me a better idea and more accurate histogram of how my exposure will look in Lightroom.  I did find I needed to reduce Saturation by 1 point otherwise the slide copies were too saturated.

(NOTE:  Normally the camera's settings are for JPEG files and the RAW images are not affected.  However, with the Z7, I found that the in-camera settings are ported over to the sliders in Lightroom Classic CC upon import.  For example, when setting most cameras to a Film Simulation or Picture Control (Style), Adobe Color will appear as the profile in Lightroom when importing the RAW file.  Not with this camera.  Whatever you have set in your camera, translates to the initial settings, including Camera Profile, shadow detail, saturation, etc. in LR.  So, setting a parameter in-camera has an effect after import.)

Is copying the slides in RAW format necessary or will a JPEG file be adequate, although it won't give the absolute best image quality?  Is the trade-off of file size versus quality something that I should consider?

Initially in my testing, I only used RAW.  Then, when conducting some of the white balance tests, I set my camera for RAW plus JPEG.  I then went into Lightroom and edited both types of files.  I am hard pressed to see any real quality differences.  I'm sure someone will tell my why I should use only RAW.  I know that advantages when making original digital image files.  However, copying these slides is not like being out in the countryside photographing a landscape with brightness range from specular highlights to deep black shadows.  Slides have only a 5 or 6 stop dynamic range.  With slides, you get the exposure right in-camera or you lose either highlight or shadow detail.  There is little room for error.  Today's digital cameras have from 12-14 stops of dynamic range and both RAW files and JPEGs will record about the same. (I'm not talking about 8-bit vs. 12 or 14-bit files which refer to color depth)  There won't be major editing done to these files as there would be in a normal digital file.  I'm really copying a finished product of limited dynamic range with colors pretty much already corrected.  When considering between the two file types it is more about how much quality will be lost in the JPEG compression algorithm than anything else.  Since there will be little manipulation of the files in editing, the 8-bit versus 14-bit argument really doesn't apply either, in my opinion.  Colors won't be drastically changed or corrected.  No banding should be seen.

I don't think, strictly speaking, the benefits of RAW files really need to be invoked when copying slides as long as you keep your in-camera JPEG settings to low contrast, no sharpening, low saturation, etc.  There will be very little white balance adjustment and very little overall editing adjustments needed.   A JPEG file should be able to handle it well.  I think a JPEG digital file of a copied slide would work fine for most slides, but that being said, I'm going to stick with RAW.  I'll give up the extra hard disk space for that little extra "potential" benefit.  I'm not sure there really is a benefit but that is just me.  However, for a quick slide copy sometime in the future, I think JPEG with my setup will work just fine.  

Another early test copy.  In the original file at 100% (circled area), there was some really ugly grain with artifacts on
the tree trunk and in the needles of this conifer.  I think I've found a solution to this issue. (click to enlarge)

What problems have you encountered?

I've made over a hundred tests using several different slides with different characteristics—Kodachrome, Ekatchrome and Velvia—and have found two troublesome issues which I need to resolve.  I've also found one limitation.

The first troublesome issue is that in the shadow and dark areas of some slides, I'm seeing a lot of ugly film grain with some weird artifacts.  I think it looks bad and I need to find a way to correct it.  

The second issue I've encountered is I'm seeing subtle purple/magenta areas appearing in the blue areas of skies as well as in bluish shadows (open shade), such as a white wall in shade with a blue sky above.  I've also seen it in blue jeans.  I need to find out why there seems to be  magenta/purple areas showing up in bluish medium tones when no magenta/purple is present.  

The limitation I've found is that my macro lens only focuses 1:1.  That is okay for negatives but slides are mounted in cardboard holders, with about 1/8" of the actual slide obscured by the cardboard.  I would like to focus in closer than 1:1 to copy only the slide, and exclude the edges of the cardboard mount (see below), but can't get that close.  It would have to focus just a little closer to exclude the edge of the cardboard.  That means every slide copy has to be cropped.  I've looked at creating a preset to automatically crop slides en masse, but that really won't work as there are differences in each slide copy as to how much needs cropped on each of the four sides.  It will have to be done manually—or I can leave them as is.

I'll address the magenta/purple issue in the next post.  As far as the grain and color anomalies in the shadows, I think I may have that solved with changes in exposures.  It is worse when I try to extract shadow detail.  I may just only need ensure my exposure is normal and not brighter than normal.  We'll see.

This is a 1:1 copy.  You can see the black of the cardboard slide mount.  The lens and digitizing system doesn't
allow you to focus closer than this so cropping will have to be done for every slide copy. The other alternative
is to leave the "frames" intact giving it the vintage look.  (click to enlarge)

That's enough for now.  In my next post, I'll lay out a summary of my camera settings upon which I've settled to finalize the process.

Join me over at Instagram @dennisamook or my website, www.dennismook.com. 

Thanks for looking. Enjoy! 

Dennis A. Mook 

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