I thought I would share my system and equipment for scanning 4x5" and 5x7" negatives for HABS/HAER/HALS. (definitions here: HABS LINK)

I took a column from a Beseler slide duplicator and added a box with LED lights that has an 8x8" light source in a box. The box has small cooling-fans and vent-holes at the bottom that turn on when positioning the negative on the base with the Ikea LED "dust-light."

Two big switches on the front of the box turn on/off the lightbox/dust-light. I have 1/4 inch frosted plexiglass at the top of the 8x8" lightbox, and above that, have a floating, masked, 1/4 inch, frosted, plexiglass sheet masked to 4x5" or 5x7" depending on which format I am duplicating.

Negatives are wiped on both sides with gloved fingers to remove dust. They are put emulsion down onto the plexiglass sheet and, with the dust-light on, I chase dust particles by wiping with my cotton-gloved fingers. (I use a lint roller in a stand to clean the gloves as I go).

When I have removed all particles, I turn off the dust-light and turn on the lightbox (front switch), and expose x3. I then flip on dust-light and double check that no new dust has landed on the negative during exposure. HABS/HAER/HALS prints (scans) must be done with the rebate edges and film-notch of the film showing so there is no top-perimeter mask in my process. If negatives want to curl (about 30% of time) I use tiny weighted wires to hold down the corners which leaves tiny white marks in the rebate edges.

Camera is a stock Nikon D800E with a Nikkor 60mm Macro 2.8D/AF lens. Used on Manual focus using the 10X live-view to focus before every session (I have a silicon bracelet on the focus ring to lock focus). Exposures are around f9 at 1/8 sec @100ISO.

(Room-lights off) Exposure is directly into Lightroom using tethered capture (USB-3) on an old Mac Pro Cheesegrater Tower running Legacy Lightroom (Version 6) because it's offline in my darkroom and only used for scanning. A RAW (NEF) -14bit capture is trigged using a Nikon remote cable using Mirror-Up-Expose with two clicks of the remote button (six clicks = three brackets). Exposure is generally set to AUTO at f9 unless it is a troublesome neg. Bracketed three exposures: -2/3, N, +2/3

Because my old Cheesegrater scanning computer is slow, all Lightroom processing is minimized for speed. All Lightroom develop settings are set to zero or defaults, with 0 sharpening/detail/noise reduction, and no lens corrections/transformations. Only the CURVE is inverted in the curves dialog to show a positive view of exposure. A new LR library is begun for every scanning session (usually 12-100 negatives) on the SSD system disc to keep the sluggish Lightroom process from getting bogged down. After the session is complete the NEFs and catalog are transferred off the SSD system disc to a portable hard drive and brought to the studio to the color managed/calibrated iMacPro. The images are brought into my main Lightroom workflow through "Import as Catalog" (after the mobile LR catalog on the portable HD is upgraded to latest Classic LR 12+ version) images are then moved to onto my main RAID. They are batch processed as NEF to DNG, and a preset is applied to the lot to apply sharpening/lens corrections/develop settings, newest calibration, etc. The best scan is chosen from the brackets, labeled RED, and then individual exposure adjustments and filters, cropping, curve-tweaks, and dust spotting (including white wire marks) are completed on each "select" negative.

Here are some photos of the physical setup.
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Room lights on, lightbox on.

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Room lights off, lightbox on.

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Raking dust-light on.

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Close-up showing raking dust-light illuminating gremlins.

(I will post some full-sized negatives scans from the system and link to the jpegs and raw negative files.)

For me, this setup produces contact-size 4x5" or 5x7" @ 720ppi prints for HABS and my clients and the occasional 8x10" or 11x14" at 720PPI print for presentation. The negatives will be scanned again at the Library of Congress (probably with a 150MP Phase-One system) at some point in the future (currently a decade-long backlog). Heritage Documentation Programs (HDP) the administrators of the National Park Service (NPS) programs and the Library of Congress (LoC) consider the delivered, public domain negative to be the "artifact." Their goal is a negative life expectancy of 500 years, so the scan and the print are just a viewing tool for the negative.

Some of the idiosyncrasies are because of the special rules or specific requirements of the HDP process, It's far from perfect, but it works well for me.

Cheers,