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General Photography
Macro
Is a macro lens better than extension tubes
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<blockquote data-quote="WayneF" data-source="post: 319410" data-attributes="member: 12496"><p>Regarding loss of light at large magnification: It is not just extension tubes, it is any lens, specifically including macro lenses. Macro lenses suffer the same light loss doing extreme magnification. Macro lenses just are recalibrated to indicate the correct lossy value (when focused close). <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /> </p><p></p><p>Closeup filters (magnifying glass in front of lens) is the only solution without light loss, but these won't reach 1:1, and are sort of an optical kludge (better ones can work though).</p><p></p><p>If you have a f/2.8 macro lens, set it to f/2.8 (at some larger distance). Then focus it as close as possible, to 1:1 magnification. It now indicates more like f/4.8 to f/f5.6 (ought to be two stops loss at f/5.6, but internal focusing can do tricks). However, this is typically metered through the lens anyway, but if using a hand held meter, you have to know this.</p><p></p><p>A chart, applicable to physics, not to any specific lens:<p style="margin-left: 20px">0.1 magnification - loss of 1/4 stop. Lots of lenses focus this close. Some calibrate theirself accurately.</p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px">0.5 magnification - loss of 1.3 stops</p> <p style="margin-left: 20px"></p> <p style="margin-left: 20px">1.0 magnification - loss of 2 stops (this is the 1:1 magnification that macro lenses typically can do).</p> <p style="margin-left: 20px"></p><p></p><p></p><p>The choice of macro lens or extension tubes is a big choice with very vast differences.</p><p></p><p>Put a 28 mm tube on a 50 mm lens, and </p><p></p><ul> <li data-xf-list-type="ul">It still will not reach 1:1 magnification (1:1 needs extension comparable to the focal length). </li> <li data-xf-list-type="ul">It will only offer ONE magnification - whatever it does is the only choice it offers. </li> <li data-xf-list-type="ul">Ability to focus will be lost. At large magnifications, the focus ring will have extremely small effect (essentially does near nothing, and the closer to 1:1, the less it does.) So we have to focus by moving the camera back and forth, to find the one spot where it can focus. </li> </ul><p></p><p>Switch to a real macro lens, and</p><ul> <li data-xf-list-type="ul"> It will easily focus from infinity to 1:1 magnification, no issue at all. Auto focus normally works fine, at any distance. </li> <li data-xf-list-type="ul"> It will offer wide range of many magnifications, at any of these distances where it easily focuses. </li> <li data-xf-list-type="ul"> Again, it easily focuses at any distance. You only move the camera to change the magnification value, to be a more close up view. </li> <li data-xf-list-type="ul">Plus, it is optically corrected for these close distances. </li> </ul><p></p><p>We are of course now out about $400 to $1000 to buy the macro lens, but it really is like day and night. No longer primitive.</p><p></p><p>The extension tube can work, but it only does what it does, and only in its way.</p></blockquote><p></p>
[QUOTE="WayneF, post: 319410, member: 12496"] Regarding loss of light at large magnification: It is not just extension tubes, it is any lens, specifically including macro lenses. Macro lenses suffer the same light loss doing extreme magnification. Macro lenses just are recalibrated to indicate the correct lossy value (when focused close). :) Closeup filters (magnifying glass in front of lens) is the only solution without light loss, but these won't reach 1:1, and are sort of an optical kludge (better ones can work though). If you have a f/2.8 macro lens, set it to f/2.8 (at some larger distance). Then focus it as close as possible, to 1:1 magnification. It now indicates more like f/4.8 to f/f5.6 (ought to be two stops loss at f/5.6, but internal focusing can do tricks). However, this is typically metered through the lens anyway, but if using a hand held meter, you have to know this. A chart, applicable to physics, not to any specific lens:[INDENT]0.1 magnification - loss of 1/4 stop. Lots of lenses focus this close. Some calibrate theirself accurately. 0.5 magnification - loss of 1.3 stops 1.0 magnification - loss of 2 stops (this is the 1:1 magnification that macro lenses typically can do). [/INDENT] The choice of macro lens or extension tubes is a big choice with very vast differences. Put a 28 mm tube on a 50 mm lens, and [LIST] [*]It still will not reach 1:1 magnification (1:1 needs extension comparable to the focal length). [*]It will only offer ONE magnification - whatever it does is the only choice it offers. [*]Ability to focus will be lost. At large magnifications, the focus ring will have extremely small effect (essentially does near nothing, and the closer to 1:1, the less it does.) So we have to focus by moving the camera back and forth, to find the one spot where it can focus. [/LIST] Switch to a real macro lens, and [LIST] [*] It will easily focus from infinity to 1:1 magnification, no issue at all. Auto focus normally works fine, at any distance. [*] It will offer wide range of many magnifications, at any of these distances where it easily focuses. [*] Again, it easily focuses at any distance. You only move the camera to change the magnification value, to be a more close up view. [*]Plus, it is optically corrected for these close distances. [/LIST] We are of course now out about $400 to $1000 to buy the macro lens, but it really is like day and night. No longer primitive. The extension tube can work, but it only does what it does, and only in its way. [/QUOTE]
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Is a macro lens better than extension tubes
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