NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Eye problems and IE, IC
From: Bill B
Date: 2006 Jul 14, 19:39 -0500
TEST FOR SHADE SHIFT
The sextant was held in the usual vertical position. For the filter shots a
pack of 4 neutral-density optical-grade gelatin filters were mounted in a
cardboard carrier, which was butted to the barrel in front of the objective
lens of the scope and secured with masking tape. The filters were ND 3.0,
ND 2.0, ND 1.0 and ND 0.7, totaling ND 6.7.
For the shade observation, three identical shades were used in front of both
the horizon and index mirrors. The shade packs consisted of 1 dark green, 1
light green, and 1 neutral density shade per pack.
Order of observations. Observations were made in batches. On the arc with
shades, then on the arc with filter pack. The data from the first two
observations was processed to determine if off the arc observations with
both shades and filter pack would be necessary. Based on the correlation,
off-the-arc observations were made with shades only.
Based on these trials, it would appear that any difference between no-shade
natural horizon IE and sun IE is not caused by a shift caused by combined
shades. Further testing with the moon and no shades will be conducted as
conditions permit.
Bill
14 July, 2006
Left eye 16:15 to 16:40 EDT
Hc 55d to 50d
KEY
SON (shades on the arc)
SOF (shades off the arc)
FON (filters on the arc)
sigma (standard deviation)
Vertical Vertical Vertical
On Arc w/ On Arc w/ Off Arc
Shades filters w/ shades
31.8 31.8 28.8
31.8 31.9 28.8
32.0 31.9 28.9
31.8 31.8 28.8
31.9 31.8 29.0
31.8 31.8 28.8
31.8 31.8 28.9
31.8 31.9 28.8
31.9 31.8 28.8
31.9 31.8 28.9
Mean sigma
SON 31.84' 0.070'
FON 31.83' 0.048'
SOF 28.85' 0.071'
60-SOF 31.15' -----
TARGET 4SD: 63.2'
Observed 4SD: 62.99
IE: 0.35' ON
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To , send email to NavList-@fer3.com
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From: Bill B
Date: 2006 Jul 14, 19:39 -0500
TEST FOR SHADE SHIFT
The sextant was held in the usual vertical position. For the filter shots a
pack of 4 neutral-density optical-grade gelatin filters were mounted in a
cardboard carrier, which was butted to the barrel in front of the objective
lens of the scope and secured with masking tape. The filters were ND 3.0,
ND 2.0, ND 1.0 and ND 0.7, totaling ND 6.7.
For the shade observation, three identical shades were used in front of both
the horizon and index mirrors. The shade packs consisted of 1 dark green, 1
light green, and 1 neutral density shade per pack.
Order of observations. Observations were made in batches. On the arc with
shades, then on the arc with filter pack. The data from the first two
observations was processed to determine if off the arc observations with
both shades and filter pack would be necessary. Based on the correlation,
off-the-arc observations were made with shades only.
Based on these trials, it would appear that any difference between no-shade
natural horizon IE and sun IE is not caused by a shift caused by combined
shades. Further testing with the moon and no shades will be conducted as
conditions permit.
Bill
14 July, 2006
Left eye 16:15 to 16:40 EDT
Hc 55d to 50d
KEY
SON (shades on the arc)
SOF (shades off the arc)
FON (filters on the arc)
sigma (standard deviation)
Vertical Vertical Vertical
On Arc w/ On Arc w/ Off Arc
Shades filters w/ shades
31.8 31.8 28.8
31.8 31.9 28.8
32.0 31.9 28.9
31.8 31.8 28.8
31.9 31.8 29.0
31.8 31.8 28.8
31.8 31.8 28.9
31.8 31.9 28.8
31.9 31.8 28.8
31.9 31.8 28.9
Mean sigma
SON 31.84' 0.070'
FON 31.83' 0.048'
SOF 28.85' 0.071'
60-SOF 31.15' -----
TARGET 4SD: 63.2'
Observed 4SD: 62.99
IE: 0.35' ON
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
