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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Default 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?
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Default 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.
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Default 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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