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<blockquote data-quote="WayneF" data-source="post: 227780" data-attributes="member: 12496">It would &quot;effectively&quot; or &quot;equivalently&quot; be 1.5x longer on DX.&nbsp;&nbsp; Focal length does not change of course, but the cropped view does, so that 70-200 DX appears to act like 105-300 mm on FX (as compared to FX view using those numbers). You can step back 1.5x farther for the same view on DX that FX would see.&nbsp; &quot;A couple of steps back&quot; works if you were four steps from subject.&nbsp; <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile&nbsp; &nbsp; :)" loading="lazy" data-shortname=":)" />DX gives a longer telephoto view than FX, considered an advantage for sports and wildlife.&nbsp; You can of course simply crop the FX to be 2/3 the width and height to mimic the same smaller view, but you lose 60% of the pixels when so cropping.&nbsp; But if the FX started with 24 megapixels (cropped to 10 megapixels), it would still be near DX starting with 12 megapixels (corrected math error).The big advantage of FX (lens-wise) is wide angle.&nbsp; Put 18mm on DX and it acts like 27mm on FX.&nbsp; It is relatively much harder to get wide angle on DX, because the smaller format crops much of the width away.But put 18mm on FX, and it acts like 18mm.&nbsp;&nbsp; Shows the full width view.</blockquote>

[QUOTE="WayneF, post: 227780, member: 12496"] It would "effectively" or "equivalently" be 1.5x longer on DX. Focal length does not change of course, but the cropped view does, so that 70-200 DX appears to act like 105-300 mm on FX (as compared to FX view using those numbers). You can step back 1.5x farther for the same view on DX that FX would see. "A couple of steps back" works if you were four steps from subject. :) DX gives a longer telephoto view than FX, considered an advantage for sports and wildlife. You can of course simply crop the FX to be 2/3 the width and height to mimic the same smaller view, but you lose 60% of the pixels when so cropping. But if the FX started with 24 megapixels (cropped to 10 megapixels), it would still be near DX starting with 12 megapixels (corrected math error). The big advantage of FX (lens-wise) is wide angle. Put 18mm on DX and it acts like 27mm on FX. It is relatively much harder to get wide angle on DX, because the smaller format crops much of the width away. But put 18mm on FX, and it acts like 18mm. Shows the full width view. [/QUOTE]

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