Another simple quick way to set the base exposure with a new resin or pigment is as follows:
Use the calibrationgrid.stl from
http://www.littlerp.com/?page_id=55 Start with the recommended exposure settings. Check via the mirror the build platform is sitting flat on the dish. Print a few layers and have a look at the build platform:
If there is nothing on the build platform increase the exposure 150 - 200%
If there is some xy bleed on the build platform around the spots decrease exposure by 20-30%
If only the central spots are printing boost the exposure by about 15-20%
Also when scraping the dots off the build platform they should 'pop off' :
If they slide off too easily boost exposure by about 15-20%
If they are difficult to scrape off decrease about 15-20%
This only takes a few minutes.
Once this is done the upper exposure levels can then be fine tuned using the calibration cube as goopyplastic suggests above.