NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Horizon filters not dark enough for a.h.
From: Randall Morrow
Date: 2011 Oct 14, 07:53 -0700
I noticed that when I do sun sights with a mirror artificial horizon that the sun shades were not dark enough to comfortably look at the image of the sun reflected in the a.h. mirror. Using the natural you would not normally look at the sun through the horizon glass. Presumably that's why there are four index mirror shades and only three horizon shades. (On my Davis Mark 15) In use, the over bright "horizon" sun would wash out the line between the two images making it harder to see tangency. I discovered a cheap solution to this but admit it may be introducing some extra "shade error".
Take a pair of those throw-away 3-d movie shades and pop out the lenses. Hod them up to a light source and rotate the lenses until the polarization darkens to the level you want. Then tape the two lenses together and cut off the excess plastic to get the shape you need. Using residue free blue masking tape, tape this over the outside horizon shade and you have enough filters to look directly into a mirror reflection of the sun.
Randall F Morrow PT
Senior Physical Therapist
Ergonomics Safety Consultant
Chronic Pain Program
Department of Physical Medicine
Kaiser Permanente - Kern County - Bakersfield
Phone: 661-852-3677 (Tieline - 378)
Fax: 661-852-3516 (Tieline - 378)
NOTICE TO RECIPIENT: If you are not the intended recipient of this e-mail, you are prohibited from sharing, copying, or otherwise using or disclosing its contents. If you have received this e-mail in error, please notify the sender immediately by reply e-mail and permanently delete this e-mail and any attachments without reading, forwarding or saving them. Thank you.
From: Randall Morrow
Date: 2011 Oct 14, 07:53 -0700
I noticed that when I do sun sights with a mirror artificial horizon that the sun shades were not dark enough to comfortably look at the image of the sun reflected in the a.h. mirror. Using the natural you would not normally look at the sun through the horizon glass. Presumably that's why there are four index mirror shades and only three horizon shades. (On my Davis Mark 15) In use, the over bright "horizon" sun would wash out the line between the two images making it harder to see tangency. I discovered a cheap solution to this but admit it may be introducing some extra "shade error".
Take a pair of those throw-away 3-d movie shades and pop out the lenses. Hod them up to a light source and rotate the lenses until the polarization darkens to the level you want. Then tape the two lenses together and cut off the excess plastic to get the shape you need. Using residue free blue masking tape, tape this over the outside horizon shade and you have enough filters to look directly into a mirror reflection of the sun.
Randall F Morrow PT
Senior Physical Therapist
Ergonomics Safety Consultant
Chronic Pain Program
Department of Physical Medicine
Kaiser Permanente - Kern County - Bakersfield
Phone: 661-852-3677 (Tieline - 378)
Fax: 661-852-3516 (Tieline - 378)
NOTICE TO RECIPIENT: If you are not the intended recipient of this e-mail, you are prohibited from sharing, copying, or otherwise using or disclosing its contents. If you have received this e-mail in error, please notify the sender immediately by reply e-mail and permanently delete this e-mail and any attachments without reading, forwarding or saving them. Thank you.
