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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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OT - spectacles and metal work - astigmatism
My reading / up-close glasses make square things look trapezoid.
I assume this is due to some astigmatism correction in the lenses, it makes it really hard to judge if something is square to something else when working. Has anyone had their spectacle / glasses prescription made without astigmatism correction to avoid this? |
#2
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OT - spectacles and metal work - astigmatism
On 10/10/2014 2:45 AM, DTJ wrote:
My reading / up-close glasses make square things look trapezoid. I assume this is due to some astigmatism correction in the lenses, it makes it really hard to judge if something is square to something else when working. Has anyone had their spectacle / glasses prescription made without astigmatism correction to avoid this? Go to the dollar store and get a pair of spectacles with the right magnification. They don't have astigmatism correction. If I recall correctly, the rule of thumb is spherical + half the cylindrical correction is roughly equivalent to the spherical alone. Just go try 'em to see what magnification you need. It's a catch 22. If you have little astigmatism, there won't be much distortion. If you have a lot of it, you'll have distortion, but won't see very well without correction. |
#3
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OT - spectacles and metal work - astigmatism
On 10-Oct-14 6:34 PM, mike wrote:
On 10/10/2014 2:45 AM, DTJ wrote: My reading / up-close glasses make square things look trapezoid. I assume this is due to some astigmatism correction in the lenses, it makes it really hard to judge if something is square to something else when working. Has anyone had their spectacle / glasses prescription made without astigmatism correction to avoid this? Go to the dollar store and get a pair of spectacles with the right magnification. They don't have astigmatism correction. If I recall correctly, the rule of thumb is spherical + half the cylindrical correction is roughly equivalent to the spherical alone. Just go try 'em to see what magnification you need. It's a catch 22. If you have little astigmatism, there won't be much distortion. If you have a lot of it, you'll have distortion, but won't see very well without correction. Yep the dollar store specs work fine - no distortion. Either the 1.0 or 1.5 magnifications are good. With the 1.5 magnification the vision is good but your face can end up a bit too close to the work for safety etc. I'm due for some new spectacles covered by my health insurance so I thought I'd get a decent pair made up without the astigmatism correction. |
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