Wondering if other Eggleston exhibits have featured slideshows I found Anna Kivlan's 2007 MIT thesis, which featured a quote from an interview she conducted with Eggleston’s wife Rosa, specifically about seeing the work as a slideshow:  "It was so saturated and so intense," she said. "It was astounding to see color like that.” 

Stephen Shore Eggleston in Memphis, Tennessee, December 1973 (perhaps during the visit described above)

Michael Almereyda's "Winogrand Color" describes how Winogrand had a slideshow in the highly influential 1967 "New Documents" exhibit at MOMA that also featured Diane Arbus and Lee Friedlander (who used color for portraits of musicians). But the projector malfunctioned and burned eleven slides. The slideshow was removed and after this meltdown Winogrand shot very little color.

installation view of MOMA 1967 exhibit "New Documents" showing Winogrand's slideshow: is it possible housing the projector in the custom box caused the meltdown? In 1974 MOMA had an exhibition of 40 color Helen Levitt photographs, presented as a slideshow (“Projects: Helen Levitt in Color”). The documentation for this exhibit is sparse, the MOMA site offers a single short press release. Levitt had been shooting color slides as early as 1959, but her studio was robbed and she was forced to shoot new work ahead of this exhibit. That same year Eggleston, then teaching at Harvard, discovered the dye transfer process - which gave him the ability to take his own Kodachrome slides and make deeply saturated color prints. He made a portfolio of these prints ("14 Pictures"). 

Untitled, 1972

Despite Levitt’s earlier exhibit and the fact that her color work is great, Eggleston’s 1976 exhibit at MOMA was considered groundbreaking and established him as co-king of “new color” (along with Stephen Shore, who was the first living photographer to have a one-person show at the Met, in 1971).  Hilton Kramer of the Times fell for the bait and solidly panned Eggleston’s show, telling on himself by calling it "perfectly boring."

Helen Levitt, early 1970s - the color of cars is prominent in both Eggleston and Levitt's work from this era

A mix of factors beyond blatant sexism explains passing over Levitt in the crowning of the new color photographers. She had established herself with black and white, while Eggleston appeared on the scene as color first. Winogrand's color work was similar to Levitt's in this regard. Levitt was 63, Eggleston 37. The regional content Eggleston captured (along with William Christenberry) was more exotic to the art establishment than NYC streets. Perhaps most importantly, the new color photographers had a detached mode of observation, a pop sensibility. Kramer even uses the phrase "snapshot chic" in his negative review. 

from soup cans to Wonder Bread - Eggleston, Untitled, 1970

Perhaps the slide projector made it easy to overlook Levitt's exhibit. The Kodak Carousel was connected to the experience of family vacation photos. It’s unlikely that Kramer was aware that Eggleston had been doing slideshows for years, but "snapshot chic" fits. If the art world's embrace of color photography was a decade-late concession to pop (a teenage Shore at Warhol’s Factory comes to mind), the carefully printed dye transfer print was more conservative than the slideshow.

installation view of Helen Levitt slideshow from a 2012-2013 MOMA exhibit recreating the 1974 slideshow

Understanding the "new color" of the 1970's involves a specific set of films. Kodachrome produces a positive (you can hold it up to the light and see the image). When you hold color negative (C-41) film up, it’s inverted. Sebastian Siadecki’s blog post on the myth-making around Eggleston carefully dissects often repeated half-truths by lazy art writers about both Kodachrome and dye transfer prints. He points out that, while a lot of well-known Eggleston is Kodachrome, he was using Ektachrome positive and later mostly C-41 negative film (as Eggleston felt it had improved). 

Stephen Shore describes his Met exhibit prints (presumably shot on C-41 film) as created like most snapshots of the time: "a machine in the big Kodak processing plant in Fairlawn, New Jersey, and stuck to the wall with double-sided tape." Siadecki points out Shore's early color work was shot with a Rollei 35 (a new version of this camera has been released) with Kodak Vericolor film.

Kodachrome was a superior film (in sharpness and color rendering) to the C-41 films and Ektachrome, but its limitations were less available locations to develop it, slower speed and the difficulty in printing. Kodachrome’s pleasing chiaroscuro is often a result of the slow speed, iso 25 or 64 (iso 200 arrived in 1986). Shooting an indoor scene without a flash was pushing the boundary of what could be hand-held without motion blur. While sitting in a Howard Johnson's Eggleston uses his Leica glass, shot wide open, the shadows go deep and he plays with light glinting through glass, like Dutch artists did 300 years earlier.

Untitled, 1972 / Pieter Claesz, 1643

Dye transfer printing materials have been discontinued and the printers are winding down their work in the medium. Zwirner produced an in-depth 18 minute video along with the exhibit to show how the prints were made. It shows how involved and time-consuming the process is.

This last set of dye transfer prints are fairly uniform at about 20 x 24 inches, or the reverse. This process can be fetishized like audiophiles with vinyl. After spending an hour with them, I circled back on a handful of the prints that were staggeringly perfect in tone and detail. Others could be done at this size in ink jet by a talented printer, with most viewers not being able to tell the difference. A few felt too enlarged, making the older print size (with max width at roughly 20 inches) seem preferable. 

untitled, 1972 - in person this print was the most full-tilt, perhaps over the top, example of dye transfer

The content of the slide show and the prints heavily overlapped, but there were a handful of frames in the slide show that were not hung as prints (including the famous tricycle).

Using a slide projector is harsh on slides (a very hot light bulb can fade colors and fuse dust), so the exhibit slides were reproductions, with the original tricycle safe in a temperature-controlled location. 

Some of the exhibit slides did have faded colors and dust (most obviously the abandoned airplane). I didn’t time the interval set on the Carousel, but recall it was at least 30 seconds. The gallery was not dark enough to fully experience the contrast and color saturation that Rosa Eggleston describes seeing 50 years ago.