Turning Archive

retina closes down?
Response To:
Re: Shop Lighting ()

John K Jordan
When you stare directly into the sun your retina closes down...

your retina will adjust...
your retina will continue to adjust between these work areas...
The glare causes your retina to close down requiring...
If your eyes retina is fully open you can ...


I suspect you meant to say when the pupil closes down (becomes smaller in diameter to reduce the level of light focused on the retina), or when the iris causes the pupil to adjust. Or perhaps I don't understand enough about the retina. However, I do understand that people who stare directly into the sun can suffer irreversible solar retinopathy which I suppose could be described as a permanent "closing down" of the affected retinal cells.

I find glare from light fixtures is not a significant issue when the fixtures are mounted high enough.

I don't remember if it was discussed in this thread, but when the light is brighter the pupil closes to a smaller diameter, the depth of field in the eye's camera increases and it becomes easier to focus on things near and far - eye strain from focusing decreases as the eye moves to different things. There is apparently an upper useful limit to brightness but I don't know what it is.

My shop T5 fixtures are supposedly 20,000 lumens each when all four bulbs are on giving 140,000 lumans max in the woodworking area. I usually use just half the bulbs for 70,000 lumens total when I turn on all three zones, or as low as 20,000 lumens with the two fixtures in the woodturning alcove zone. 70,000 lumens is a wonderfully comfortable general light level for me. The lumen numbers, of course, can wildly distort the story. I should get out my light meter and put some more useful lux numbers on the subject.

Also, as mentioned, diffuse lighting is absolutely not my friend when looking for scratches or other surface defects in wood or when evaluating compound curves on the lathe. I'm convinced that some of the lower quality work I've seen was due to lighting issues. Something to keep in mind. I supplement ambient illumination with task lighting fixtures.


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