hi, i was using Focal Calculator to measure that stuff, but if i want to do it by hand, where can i get the formulas to do that?

you can always PM the author of the program. dazzzla I believe created the spreadsheet in the calibration and tools area (focal calc 2)...


cheers,
gs

Un-split:
1/fl=1/lcd+1/screen
mag=screen/lcd
screensize=mag*lcdsize

split:
1/ffl= 1/gap - 1/vlcd
vmag=vlcd/gap
vlcdsize=vmag*lcdsize
1/fl=1/(lcd+vlcd-gap) +1/screen
smag=screen/(lcd+vlcd-gap)
screensize=smag*vlcdsize

Where:
fl=triplet focal length
ffl=fresnel focal length
lcd=lcd to triplet distance
screen=triplet to screen distance
vlcd =fresnel to virtual lcd distance
screensize=sreen size
lcdsize=lcd size
vlcdsize=virtual lcd size
gap= fresnel to lcd distance