I am trying to find the best differentials for me. (My first one) The pair I have now is giving me an edge of blur at about 60-70cm.
However, my work mostly involves reading at distances less than 45 cm. So I’m not getting any active focus.
Should I reduce by 0.25 to get the edge of blur at this distance? Or should I just try to get as much active focus I can with the current pair?
If your work involves you to read with perfect visual clarity, reducing won’t help as you would most likely lean forward to get that perfect clarity. If on the other hand, your work space is less than 45cm, meaning you would look like an odd person being the only person away from your table, then reducing would help. For differentials, you should do trial and error and see where you are most comfortable.
Thank you… That helps a lot
It’s all your choice. Differentials should be considered based on your own personal comfortable distance. If you do choose to reduce, keep in mind that to get from 60-70cm down to 45cm will require more like a 0.5 or 0.75 reduction.
If you don’t sit in front of a monitor, but you have to read what you are holding in your hand, then the length of your arm will decide the max distance for close-up. In this case, if it is your work scenario, yes, it would make sense to choose differentials that give you blur challenge with the arm extended (not stretched just extended to comfortable normal) and if the blur challenge is too much you can bring the object closer or you can lean closer by a few cms and work at the edge of blur.
The usual EM recommendation is with people in mind who are sitting in front of the monitor for work or school, so alternate between screen and distance. But as @anuw says if it is the length of your arm and distance for you, then the diopter gap between differentials and normalised will have to be a bit more to give you challenge and improvement.
Update: I reduced by 0.5D to get the right distance to blur.