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Nikon DSLR Cameras
D7100
D7100 buffer size - it will fill in one second?!
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<blockquote data-quote="jdeg" data-source="post: 125719" data-attributes="member: 1"><p>So to get back on topic here, one thing that was overlooked is the <strong>speed at which the camera can write to the card. </strong>This is currently unknown, but we can assume that the EXPEED 3 processor has upped the write time at least a little. T<strong>he speed of your sd card also matters. </strong></p><p><strong></strong></p><p>I found some useful data on this here: <a href="http://www.nikonians.org/forums/dcboard.php?az=show_topic&forum=329&topic_id=24879&mode=full" target="_blank">Discussion Forums @ Nikonians - D7100 buffer guesstimates</a></p><p></p><p>Buffer-emptying rate (BER) in fps is calculated as card speed/file size. The file sizes I used are the ones from the <a href="http://imaging.nikon.com/lineup/dslr/d7100/spec.htm" target="_blank">D7100 spec sheet</a> for the modes chosen.</p><p></p><p>Buffer-usage rate (BUR) in fps is the rate at which the buffer is filled minus the rate at which it is emptied (BER). Since the frame rate of the camera is taken to be 6 fps, this becomes simply:</p><p>BUR = 6 - BER</p><p></p><p>Finally, the time-to-buffer-full (TBF) is calculated as buffer size (in frames) divided by the BUR. The buffer size for each mode is also taken from the D7100 spec sheet.</p><p></p><p>In these tables, I show these values for the worst-case raw scenario of lossless-compressed 14-bit (28.5-MB files, buffer = 6) and the best-case raw scenario of lossy-compressed 12-bit (20.2-MB files, buffer = 9.)</p><p></p><p><strong>14-bit lossless</strong> (28.5 MB files, 6-frame buffer)</p><p></p><table style='width: 100%'><tr><th>Write<br /> Speed</th><th>BER (fps)</th><th>BUR (fps)</th><th>TBF (sec)</th></tr><tr><td>42 MB/s</td><td>42/28.5 = 1.5</td><td>6-1.5 = 4.5</td><td>6/4.5 = 1.3</td></tr><tr><td>60 MB/s</td><td>60/28.5 = 2.1</td><td>6-2.1 = 3.9</td><td>6/3.9 = 1.5</td></tr><tr><td>90 MB/s</td><td>90/28.5 = 3.2</td><td>6-3.2 = 2.8</td><td>6/2.8 = 2.1<br /> </td></tr></table><p></p><p>I highly doubt you're going to get 90 mb/s into the sd card, but if you can get 60, that means you could get a 3 seconds of continuous shooting at 12 bit lossy compression before the buffer starts to slow you down. Otherwise you'd be seeing 1.5 seconds until the buffer fills at 42 mb/s</p></blockquote><p></p>
[QUOTE="jdeg, post: 125719, member: 1"] So to get back on topic here, one thing that was overlooked is the [B]speed at which the camera can write to the card. [/B]This is currently unknown, but we can assume that the EXPEED 3 processor has upped the write time at least a little. T[B]he speed of your sd card also matters. [/B] I found some useful data on this here: [url=http://www.nikonians.org/forums/dcboard.php?az=show_topic&forum=329&topic_id=24879&mode=full]Discussion Forums @ Nikonians - D7100 buffer guesstimates[/url] Buffer-emptying rate (BER) in fps is calculated as card speed/file size. The file sizes I used are the ones from the [URL="http://imaging.nikon.com/lineup/dslr/d7100/spec.htm"]D7100 spec sheet[/URL] for the modes chosen. Buffer-usage rate (BUR) in fps is the rate at which the buffer is filled minus the rate at which it is emptied (BER). Since the frame rate of the camera is taken to be 6 fps, this becomes simply: BUR = 6 - BER Finally, the time-to-buffer-full (TBF) is calculated as buffer size (in frames) divided by the BUR. The buffer size for each mode is also taken from the D7100 spec sheet. In these tables, I show these values for the worst-case raw scenario of lossless-compressed 14-bit (28.5-MB files, buffer = 6) and the best-case raw scenario of lossy-compressed 12-bit (20.2-MB files, buffer = 9.) [B]14-bit lossless[/B] (28.5 MB files, 6-frame buffer) [TABLE] [TR] [TH="align: right"]Write Speed[/TH] [TH="align: right"]BER (fps)[/TH] [TH="align: right"]BUR (fps)[/TH] [TH="align: right"]TBF (sec)[/TH] [/TR] [TR] [TD]42 MB/s[/TD] [TD]42/28.5 = 1.5[/TD] [TD]6-1.5 = 4.5[/TD] [TD]6/4.5 = 1.3[/TD] [/TR] [TR] [TD]60 MB/s[/TD] [TD]60/28.5 = 2.1[/TD] [TD]6-2.1 = 3.9[/TD] [TD]6/3.9 = 1.5[/TD] [/TR] [TR] [TD]90 MB/s[/TD] [TD]90/28.5 = 3.2[/TD] [TD]6-3.2 = 2.8[/TD] [TD]6/2.8 = 2.1 [/TD] [/TR] [/TABLE] I highly doubt you're going to get 90 mb/s into the sd card, but if you can get 60, that means you could get a 3 seconds of continuous shooting at 12 bit lossy compression before the buffer starts to slow you down. Otherwise you'd be seeing 1.5 seconds until the buffer fills at 42 mb/s [/QUOTE]
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D7100 buffer size - it will fill in one second?!
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