Yeah Stu, I'd rather talk about this than a FF 500 MP whatever.
I posted that last response kinda quickly and should expand it a little.
Lets say you want to photograph a small object the size of a house fly that is static. You can get or make a light tent to put the item in and light it from the outside to cast an even light. Generally 2 or 3 lights will fill in all the shadows just fine. You can do the same with regular lamps surrounding the subject and diffused with a cloth in front of each.
An example can be found here on Ebay:
PHOTOGRAPHY STUDIO LIGHT TENT 30W CFL BULB STAND KIT - (eBay item 260152493606 end time Aug-27-07 20:57:09 PDT)
The advantage here is that the lights are on during setup and you can compose, focus and so on with enough light to see everything in the viewfinder.
The type of light used can make a difference as each has it's own temperature that casts a different light colour:
Fluorescent lights are sort of greenish typically but many types are available with colour temperatures of 2200 to 5600 depending on the phosphors and wattage.
Common incandescent lighting is reddish (about 2700
degrees K color temperature).
Quartz halogen lights are also reddish (3200 degrees K). Outdoor light is usually bluish, (about
5400 degrees K) except during sunrise and sunset.
Take an ordinary lamp and add 30-45 watt flourecent CFL or HMI 5500K bulbs. They will give you about the same as your flash and close to outdoor sunlight. Then once you have the setup in place, manually set your white balance on the camera. This will help the image look natural and not washed out.
If you want to just use one light source (sunlight from a window) then use reflectors to circle the subject and fill in the shadows. It's cheap and offers the right colour temperature but you will have less time to work as the sun moves. White cards will do the job just fine. The same can be done with one lamp but still requires white balancing. Here I used the sun on one side behind the camera and a lamp behind the other side of the camera with a reflector behind the subject facing the camera.
https://www.pentaxforums.com/gallery/photo-2506.html
White balance instructions are included in the camera manual and each does it a little differently. You can use a white card or 18% grey card that reflects the light you are using. Better yet take a piece of semi transparent white (it must be pure white) plastic, cloth or paper ( a coffee filter does this well) and place it over the lens. Then point the lens into your macro setup with the lights on and set the balance according to the cameras instructions.
If you have a couple of old large filters you can place the coffee filter between them and screw them together creating a white balance filter holder. Just hold it in front of the lens and do your white balance. it's great for other shooting as well. Like inside a church where the light could be coming from natural and man made sources as well as stained glass all at the same time. Everyone will be amazed how your pictures look so natural when all theirs look green or red.
I'm not really addressing ring lights or ring flashes because I can't find a ring flash that works with P-TTL and not sure if there is a version around with enough manual control to work well with a Pentax. Ring lights look like they may do well but I don't own one so can't really comment on how good they are.
I'd like to have others add to this thread if they have suggestions or ideas for this setup.