|
Author
|
Topic: Artificial Horizon Shades
|
MJames
|
posted January 29, 2015 02:05 PM
I have one question regarding the Artificial Horizon I just received.
When taking a noon sighting, I notice that when using both filters on the AH and using both horizon shades on the Mark 3 sextant, the greenish AH sun image is noticeably brighter than the very dim orange image I'm able to get from the index mirror shades.
I know the AH shades should be designed for optimal protection, but I'm very paranoid about my eyesight. So I just want to make sure that the combination of the two AH shades with the two Mark 3 sextant horizon shades is sufficient for noon sun sightings.
Thanks
|
|
Capt Steve Miller
|
posted January 29, 2015 03:24 PM
You did not say what kind of AH you are using.
I have a Davis AH and I generally use a clear glass and the Blue plastic plate when the AH is in use.
I adjust the shades on the sextant so that I can see the images 'comfortably'. The 'comfortably' will change per the user's preference, so there is not a standard amount of shades to use.
From: Starpath
|
|
David Burch
|
posted January 29, 2015 03:26 PM
Sextant and AH shades are not designed for eye protection per se. They are provided to let the user achieve a view of the sun that is optimum for taking sun sights.
Too dark means you cannot see the edges carefully; too bright is the same in the other extreme.
We recommend that you choose the combination of shades that leaves the images as bright as possible without giving any impression of "brightness."
This is obviously subjective, but try that as a guide. If you might consider what you are looking at as possibly too bright then look for a different combination that is a bit less bright.
Usually there are multiple combinations to work with, but once you have it figured out you will have a feeling for how to proceed.
Note that when using an artificial horizon (AH) with a liquid surface you are not looking directly at the sun, so there is not much risk of eye damage, no matter how bright it might appear.... but we still do not want it to "appear" bright, because, if so, it distorts your concept of alignment with either itself in the AH or with the horizon at sea. (I assume you are not using a mirror for the AH, but rather some liquid surface.)
PS, in the back of the How to Use Plastic Sextants book there is a section on how to make a Bader sun filter, which does have many nice applications, as we discuss in that book... but not for AH use. This is for looking toward the sun, where indeed eye protection is crucial.
From: Starpath, Seattle, WA
|
|
|
