This used to entail special film and special lights and sending the special film away for processing and paying for said processing and then tossing out the inevitable bad slides and feeling a little sad about the cost and the effort.
Eventually real slides meant endless hours at a slide recorder when everyone started asking for a CD of .jpgs or .tiffs in application materials rather than a carousel or set of slides. I bridged this gap in my early career. In college and afterwards almost all applications required physical slides. When I applied to graduate school, some schools wanted digital but I remember sending off several bulky slide carousels too. I vaguely remember giving at least one talk on my work using a slide carousel.
By the time I finished graduate school, no one was asking for physical slides anymore and Kodak had stopped making carousels.
I haven't actually made or used a slide in years. But "taking slides"sounds better (and is quicker) than saying I am "taking digital images of my artwork for use in job and exhibition applications." When I used to take actual slides, it was clear I was talking about making something to record and promote my artwork. Now I'm as likely to fill my digital camera's memory card with pictures of my daughter as with pictures of my artwork; there isn't a physical distinction between the two types of images.
Anyway, "slides" is what I've been doing this week.
When I am taking slides (er, making images), I find it is sometimes hard to judge the quality of the image at immediately. I get into a rhythm and take a bunch of images but I have to come back to the computer (and often the printer) before I can "see" if the images work. I also find that time and distance helps. I am better able to judge the quality of the images I took last year than this. Similar to judging the quality of the work itself, judging the quality of the slides right after making the work is difficult because the actual image competes with the image in my head, my feelings about the process and my hopes for the piece.
Looking back at last year's images, I realize that several are quite dark and have a blue-ish background rather than grey. This year (so far) I don't have that problem, but I don't remember changing anything about the process of setting up, lighting or taking the images.
My method isn't necessarily an official or approved method for taking slides. It certainly wasn't how I was taught, but, then, I am not a film camera and freedom from processing fees means I can quickly delete or retake images that don't work out.
In college I learned to use tungsten lights and a depth of field with a long exposure and one of those cords on the camera that allows you to click without moving the camera. We had a diffuser light of some sort and lights on stands. Slides were taking in a room specifically devoted to taking slides (and maybe storage, too. In graduate school we adopted a small room that was slightly less dusty than the rest of the clay studio. We built our own diffuser out of a light hanging from an extension cord with a cardboard box around it and a filter over the opening. If I recall correctly, the filter was the kind used in a heater. We covered the windows with paper and tried to get the lights far enough back that they wouldn't create shadows.
At my home studio, or, rather, outside of it, I hang my big roll of grey photo paper from an old clothes rack (came with the house, don't know why) with plastic clamps and drape it over my daughter's art table. I do this early in the morning so I can use the daylight just after dawn when shadows are more diffuse. I set a long depth of field and adjust the light meter as the sun comes up.
I don't think this method is orthodox but neither can I have a permanently dedicated "slide" area in my studio or home. Also, tungsten lights get really hot and unpleasant and my only real enemy outside in the morning is the wind. The wind almost won a small object from my "slide" table when it blew the grey paper and rolled the piece to the edge. Luckily I was standing there and caught it before it fell.
I took 135 images of 48 objects this morning and yesterday morning. A few were retakes of work completed last year or before. Taking advantage of dawn's early light means that by the time my daughter wakes up I've already accomplished something for the day!