Wikipedia:Featured picture candidates/Using the sextant

Using the sextant


This is a didactic animation to illustrate the use of the marine sextant to measure the Altitude (astronomy) of the Sun at sea. A detailed explanation of the frames is in the image file. The animation appears in the article sextant.

Image created by Joaquim Alves Gaspar

The sequence is too fast, you can't actually understand what is going on without watching it a large number of times. The picture transitions is very blocky, could it be made into a smooth animation like the "pi unrolled" FP? The numbers in the corner should relate to the steps required to use a a sextant not the frame number of the animation. The animation can't be understood by itself, you have to read the explanation at the image page - all the relevant information should be on the animation without requiring reference to external sources. Witt y lama 17:50, 31 October 2006 (UTC) :: Please help, I cannot make the thumbnail here visible. - Alvesgaspar 09:36, 2 November 2006 (UTC)
 * Nominate and support. - Alvesgaspar 11:28, 31 October 2006 (UTC)
 * Comment. I like this animation a lot, but one thing to note. It isn't altitude that you're measuring (which is the DISTANCE above the surface of the earth) but the angle of the sun from the horizon. You will need to change the caption and the comments on the image page. Also, surely when you tilt the sextant, the horizon in the left pane will also tilt? Diliff  | (Talk)   (Contribs) 12:06, 31 October 2006 (UTC)
 * Info. The correct technical term, used both in British and American English, is really altitude: the angular distance between the horizon and the body. The word is used in Astronomy, Geodesy and Navigation. In this case, it is called the sextant altitude. To get the apparente altitude, we still have to correct all sistematic errors (due to instrument, observer and depression of the horizon). When the sextant is tilted, the horizon seen through the telescope remains horizontal, only the image of the mirror/glass rotate (I have done it a lot of times, believe me!) ;-) - Alvesgaspar 12:15, 31 October 2006 (UTC)
 * Then I apologise. I've never heard the word altitude used in that way! How does the telescope remain horizontal? I'm assuming that it rotates on its axis somehow? I've added a link to the Altitude (astronomy) article in the introduction to the nomination. ;-) Diliff  | (Talk)   (Contribs) 12:28, 31 October 2006 (UTC)
 * Yes, we rotate the instrument around the optical axis of the telescope, maintaining its ocular close to the eye! -
 * Weak oppose. There is a bright line appearing and disappearing in the middle of the animation. And I'd like the light path to be visible from the beginning (maybe thinner or transparent) and the sun (or direction of the sun) indicated in the overview. The tilting of the sextant looks like a squeezing not a rotation. Otherwise a nice animation. --Dschwen 14:25, 31 October 2006 (UTC)
 * Comment. There's a lot going on simultaneously in this animation, it might be easier to follow and understand if it was a bit slower and smoother. --KFP (talk | contribs) 17:40, 31 October 2006 (UTC)
 * Oppose. I oppose this particular version but I'm really looking forward to an improved one - this would be a very useful FP.
 * Oppose There is also a bad looking wiggle when the sextant is tilted. This animation can certainly be improved. --Janke | Talk 19:55, 31 October 2006 (UTC)
 * Oppose per above. I'd support a version that addresses these issues.  howch e  ng   {chat} 22:15, 31 October 2006 (UTC)
 * Oppose I had to watch the animation a dozen times before I figured out what was going on, and I had to read the image page to understand the captions. The first few captions went by too fast for me to read. --Andrew c 23:16, 31 October 2006 (UTC)
 * Info. Thank you for all the suggestions which I hope will help to make a much better animation. Please hold your votes until it is done. - Alvesgaspar 00:01, 1 November 2006 (UTC)
 * Information. Voilà, the new version of the sextant is ready. The animation is now smoother and a bit simplified. I decided to include the light rays only at the begining and at the end, otherwise the image would be too cluttered. But the sextant is a working replica, i.e., the angles and reflections are all correct. - Alvesgaspar 21:34, 1 November 2006 (UTC)
 * Support Edit 2. The new version is much clearer. Nautica Shad e  s  12:45, 2 November 2006 (UTC)
 * VERY weak Oppose New version is great, but I still would not mind seeing the blue reference lines throughout the animation. It may show better how the mirror swings up toward the sun.  Any chance we could have a 3rd version just to see? --Bridgecross 14:32, 2 November 2006 (UTC)
 * I feel like you are puting me to work... - Alvesgaspar 21:23, 2 November 2006 (UTC)
 * Strong oppose Edit': part of the animation was lost: You see the sun swinging about the horizon, but DON'T SEE THE SEXTANT SWING INTO AND OUT OF THE PICTURE anymore. Adam Cuerden talk 00:28, 3 November 2006 (UTC)
 * Oppose edit per above. --Janke | Talk 07:50, 3 November 2006 (UTC)
 * Info. This is the third and last version. The swinging is back, although more discreete, and I have also included the light rays. - Alvesgaspar 01:33, 5 November 2006 (UTC)
 * Oppose all. It's a good image once you watch it a dozen times...but maybe that's just because it's a complicated instrument for those new to it. But there are other problems. You can't tell it's swinging without reading the text, the image would benefit from an indication of where the sun is relative to the sextant, and the text should be capitalized. Finally, for aesthetics, I would like to see the glass view (the circle) on the right and the sextant on the left, with the numbers and text together on the left side. -- Tewy  03:10, 5 November 2006 (UTC)
 * Oppose An okay animation. But I find that most animations are too fast for me to get the gist of it in one go round. &mdash; Ultor_Solis (talk • contribs) 01:48, 8 November 2006 (UTC)

- Mailer Diablo 19:04, 10 November 2006 (UTC)