NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2015 Aug 19, 10:43 -0700
The 35mm Super Takumar lens calibration continues. For the lower altitudes the natural horizon is used (below 2200 pixels). The data points are a good fit with the artificial horizon data points. The last 10° of altitude down to sunset will have to wait for another day when there is a cloud free horizon.
Greg Rudzinski
From: Greg Rudzinski
Date: 2015 Aug 13, 09:00 -0700The first artificial horizon Sun observation by calibrated 35mm fixed prime lens has been made this morning. (see original image)
Pixel count by Windows paint 3029 pixels x .57' = 1726.5' - 41.5' corr. = 1685' = 28° 5' AHs / 2 = 14° 2.5' Hs -3.8' ref. = 13° 58.7' Ho
8/13/ 2015 UT 07:30:19 Lat 34° 10.5' N Lon 119° 13.8' W
GHA 36° 21.4'
LHA 277° 7.6'
DEC 14° 38.5' N
Hc 13° 57.8'
Ho 13° 58.7'
Int 0.9' toward
Az 81.6° true
Very pleased with result :)
Image settings: f8, ISO 200, 1/1000 sec, infinite focus.
Double polarizer used on artificial horizon reflected Sun (blue). Solar film used on direct Sun (orange).
Greg Rudzinski
From: Greg Rudzinski
Date: 2015 Aug 12, 13:53 -0700Attached is the correction graph for the Super Takumar 35mm lens on a Canon Rebel xti 10 MP body. Looks to be just a single outlier for the artificial horizon data points. Three consecutive images were averaged for each point. Low altitude natural horizon image calibration to follow.
Greg Rudzinski
From: Greg Rudzinski
Date: 2015 Aug 9, 16:39 -0700The 35mm Super Takumar legacy prime lens is spectacular on the Canon Rebel xti 10 MP body. Sharp edge to edge with a field of view of 38°. Minutes of arc per pixel is .57'. A full calibration will follow. The good news is the price of $30 free shipping for a lens in mint condition. Haven't snapped a bad pic yet :)
Greg Rudzinski
Attached File:
(Super-Takumar-35mm-Sun.PNG: Open and save)
Attached File:
(Canon-Rebel-DSLR-w-Super-Tak.jpg: Open and save)
Attached File:
(Cal-35mm-Super-Takumar.jpg: Open and save)
Attached File:
(35mm-Super-Takumar-Obs.-1.jpg: Open and save)
