Range of accommodation and finding active focus

After almost a year seeking Active Focus at near, midrange and distance I am closing in on the last of the bunch namely distance. I am surprised that the forum discussion has not come around to quantifying the “range of active focus” apparently. Perhaps the forum actors who have thought at greater length than I have about the optics of this situation can confirm or correct the following.

Active Focus means voluntary accommodation, correct?

Accommodation range is limited to the range allowed by the optics and biology of the person. It generally follows the following age-related curve, corrrect?
N.B. I just uploaded the graph/image as jpg and deleted the previous inline image that users below noted as not readable. Maybe this change will make the graph viewable by all users.


I measured my own range and came up with about 1 meter (i.e.the range is plus or minus one-half meter or one meter total). My age is 69. That matches this graph and others online.

In other words it would be generally useless for me to try to use my voluntary accommodation to “clear” 8 D of blur via AF but entirely possible for a 30 year old.

Another way to say this: what I can clear with AF must fall within the range of optical possibility for my age. For example that increase in clarity for me is the difference between a Snellen seen at 17 feet and one seen at 20 feet – which is not microscopically subtle but is not grossly obvious either. Likewise that minor degree of available clearing is tricky to apply to outdoor targets of arbitrary size and distance.

Although I continue to work on AF in daily one-hour outdoor walks all of the above has led me to look for AF results mainly indoors with a 20 foot Snellen setup and “standard” or better lighting.

I am not sure if this is correct. I am 74, and I can AF voluntarily, or see it happen spontaneously, sometimes with surprising clarity, on my 6m Snellen. I can clear up fiddly bits on a power pylon a good distance away with AF. I could AF at 6m Snellen distance earlier than it happened at screen distance, where it now happens mainly spontaneously. I cannot concentrate on what I am reading and do voluntary AF at the same time. The text drifts in and out of greater clarity on its own.

Seems difficult to answer. I would think that the data in that chart doesn’t include people who have learned how to do active focus. Since active focus is not a medical term, but Jake’s description of how we can clear up blur, my guess is that we almost have to exclude people who have learned the EM concepts from larger published data.

Tricky to answer, and if someone has better ideas, I"ll happily defer.

Observationally, Jake has said he’s got plenty of examples of people who can do active focus at a distance who are over 70.

My experience is that I was pretty good at this to start, but the more I do it, the better and more powerfully I am able to exercise this ability.

I can’t see the chart, perhaps it’s my browser.


Right-click and “view image” should do the trick. It wasn’t showing up here as well.

It works on my phone. So weird.