I am trying to do a stepped greyscale test and am having some trouble. I have done the test numerous times (and I mean numerous), but I'm still not getting the correct results.
I am using 18% grey card.
I am doing the test in complete shade.
My camera is set to 100 and f/8 manual .
I have a couple of questions, so if you could clarify for me, that would be great!
1. I have to take a reading off the grey card and set the to get a correct leaving the at f/8. Does this mean just to take a picture of the grey card and see if the picture matches the colour of the grey card?
2. When I take 6 exposures above and below this reading, then read the RGB levels, the amounts are different. I have tried to rectify this over and over again, but to no avail. What else should I be doing?
3. Even when I have all of my exposures, starting from white, the RGB levels for the first picture should be R 255 G 255 B 255. The levels for the next from this is still R 255 G 255 B 255. The further along the scale I go, that's when the values differ at each (ie) R140 G 150 G 145.
4. Are you able to explain to me in layman's terms what the purpose of this test is. I understand that it's to measure the dynamic range of a camera, but WHY? Sorry if this is a stupid question, but am just having a difficult time understanding this.
Do you have any other hints or tips that might help me to succeed in completing this test?
Thanks so much!