Okay, you have your equipment assembled in a precise manner, as per our last posting...or in other words you have your lash-up lashed up. Now for the settings.
Most good mirrorless and DSLR cameras let you set your white balance with a number of manual choices. Past Auto you get Daylight, Shade, Flash, Underwater, etc. Avoid these - if you want to try to specify the white balance go to either Custom or Kelvin.
The Custom setting will let you take a picture of the light streaming through the slide aperture when there is no slide there. Go through the basic procedure as per your camera manual and you'll get pretty close to neutral.
If you elect to try to match the colour temperature of the light under your duplicator table with the Kelvin setting you may need to do it in a number of test shots. I found with the Metrolux that 6300ºK was pretty close but a further step in the Fujifilm settings took me to colour bias and I added 2 clicks of red and two clicks of blue. It is a case of purely subjective judgement once you look at it on the LCD screen. If you plan to treat the files later on with Lightroom you can add a biased look with batch processing and do much the same thing.
As the camera is looking at an illuminated transparency that may have light falling on it from the general room fixtures, you want to either do your copying in a space that is free of this distraction - your old film darkroom for example - or at least reduce the spillage to avoid colour shift.
Decide in what form the card will record your file - if it is a pretty straight forward sort of a slide and you are using a camera like a Fujifilm that puts out an exceptionally good JPEG, you can go for that. Choose your target size before you shoot. If you are faced with a faded or shifted slide and will need to do a lot of post-processing to bring it to life, choose the RAW file. You'll need to work on it later but there will be a lot more latitude when you need to shift stuff about.
Note that there is considerable effect on the final output with vibration of the apparatus. I play it safe with an electric cable release...though you could use the self-timer facility of most cameras to damp things down. It's not really a case of the in-camera stabilisation being useful when all components in the chain are bolted firmly down, so check and see whether you need turn the OS , IS, VC, or VC off.
And then there is the business of cleaning the slide beforehand and identifying it later...next posting.
