https://www.explainxkcd.com/wiki/index.php?title=1791:_Telescopes:_Refractor_vs_Reflector&feed=atom&action=history1791: Telescopes: Refractor vs Reflector - Revision history2024-03-29T06:03:06ZRevision history for this page on the wikiMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=1791:_Telescopes:_Refractor_vs_Reflector&diff=298054&oldid=prevJLZ0kTC5 at 22:24, 2 November 20222022-11-02T22:24:11Z<p></p>
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<td colspan="2" style="background-color: white; color:black; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: white; color:black; text-align: center;">Revision as of 22:24, 2 November 2022</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>**In theory, a refractor ''could'' be made compact, but the image quality would be awful, because the lens would have to be extremely fat. The longer the telescope is, the less dramatic the focusing needs to be.  </div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>**In theory, a refractor ''could'' be made compact, but the image quality would be awful, because the lens would have to be extremely fat. The longer the telescope is, the less dramatic the focusing needs to be.  </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>*{{w|Chromatic aberration}}:</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>*{{w|Chromatic aberration}}:</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>**In optics, chromatic aberration is an effect resulting from dispersion in which there is a failure of a lens to focus all colors to the same convergence point, producing a rainbow effect around the image familiar to people who wear glasses, and with prisms. It occurs because lenses have different refractive indices for different wavelengths of light. Each <del class="diffchange diffchange-inline">colour </del>is therefore focused slightly differently by the lens. Mirrors don't have chromatic aberration, since the light is reflected off the front of the mirror. The {{w|achromatic lens}} can reverse this effect, but it's expensive and its size is limited. Nevertheless, before telescope mirrors were perfected in the early 20th century, the best telescopes were achromatic refractors.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>**In optics, chromatic aberration is an effect resulting from dispersion in which there is a failure of a lens to focus all colors to the same convergence point, producing a rainbow effect around the image familiar to people who wear glasses, and with prisms. It occurs because lenses have different refractive indices for different wavelengths of light. Each <ins class="diffchange diffchange-inline">color </ins>is therefore focused slightly differently by the lens. Mirrors don't have chromatic aberration, since the light is reflected off the front of the mirror. The {{w|achromatic lens}} can reverse this effect, but it's expensive and its size is limited. Nevertheless, before telescope mirrors were perfected in the early 20th century, the best telescopes were achromatic refractors.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>***Note that this effect has also been mentioned in relation to photography by [[Black Hat]] in [[1014: Car Problems]], in a completely different context, but shows this is an issue Randall has considered before.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>***Note that this effect has also been mentioned in relation to photography by [[Black Hat]] in [[1014: Car Problems]], in a completely different context, but shows this is an issue Randall has considered before.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>*Reduced light-gathering</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>*Reduced light-gathering</div></td></tr>
</table>JLZ0kTC5https://www.explainxkcd.com/wiki/index.php?title=1791:_Telescopes:_Refractor_vs_Reflector&diff=272455&oldid=prev172.69.62.71: Undo revision 270749 by Explain xkcd server admin (talk)2022-05-21T00:59:44Z<p>Undo revision 270749 by <a href="/wiki/index.php/Special:Contributions/Explain_xkcd_server_admin" title="Special:Contributions/Explain xkcd server admin">Explain xkcd server admin</a> (<a href="/wiki/index.php?title=User_talk:Explain_xkcd_server_admin&action=edit&redlink=1" class="new" title="User talk:Explain xkcd server admin (page does not exist)">talk</a>)</p>
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<a href="//www.explainxkcd.com/wiki/index.php?title=1791:_Telescopes:_Refractor_vs_Reflector&diff=270749&oldid=267444">Show changes</a>Explain xkcd server adminhttps://www.explainxkcd.com/wiki/index.php?title=1791:_Telescopes:_Refractor_vs_Reflector&diff=267444&oldid=prevTheusaf: Reverted edits by 👖🔥 (talk) to last revision by Jacky7202022-05-11T18:43:32Z<p>Reverted edits by <a href="/wiki/index.php/Special:Contributions/%F0%9F%91%96%F0%9F%94%A5" title="Special:Contributions/👖🔥">👖🔥</a> (<a href="/wiki/index.php?title=User_talk:%F0%9F%91%96%F0%9F%94%A5&action=edit&redlink=1" class="new" title="User talk:👖🔥 (page does not exist)">talk</a>) to last revision by <a href="/wiki/index.php/User:Jacky720" title="User:Jacky720">Jacky720</a></p>
<a href="//www.explainxkcd.com/wiki/index.php?title=1791:_Telescopes:_Refractor_vs_Reflector&diff=267444&oldid=267002">Show changes</a>Theusafhttps://www.explainxkcd.com/wiki/index.php?title=1791:_Telescopes:_Refractor_vs_Reflector&diff=267002&oldid=prev👖🔥 at 17:54, 11 May 20222022-05-11T17:54:02Z<p></p>
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