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D7100 buffer guesstimates

dagoldst

Little Rock, US
3093 posts

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"RE: D7100 buffer guesstimates"

dagoldst Gold Member Nikonian since 02nd Dec 2012
Sun 10-Mar-13 06:18 PM | edited Sun 10-Mar-13 07:43 PM by dagoldst

> I chose to examine Sandisk Pro
>UHS-I cards, rated at 90 MB/s write speed.

UHS-I cards are rated at 45MBytes per second at 100MHZ, not 90 - I am not sure how Sandisk is making that claim unless it is the UHS-104 spec, (clocking at 208Mhz).

http://en.wikipedia.org/wiki/Secure_Digital#UHS_Speed_Class

My own rough calculation is that a single 14 bit image from a D7100 is 42.8Mbytes, so that would indicate that within 5 shots, (published buffer size), the card would be writing about 1 image per second, assuming wire speed processing through the ASIC architecture of the expeed processor.

If the D7100 supports UHS-104, it would about double the performance once the buffer is full to around 2 frames per second.

Finally, the real cure appears to be UHS-II, at 312Mbytes/sec, (again, if the ASIC processes that fast). I can't find any card like that yet, hopefully it will be out soon.

Edit to add - I am guessing the D7100 does not support the speed of UHS-II. I found that in the teardown of the D600, it uses a chip for the SD interface that is UHS-1 only...

http://guide-images.ifixit.net/igi/GpMPdA4bDfTXCARM.huge - chip is outlined in dark blue

link below is to the actual chip specs

http://product.inrevium.com/sd/te4302.html

I am guessing the D7100 shares a near identical chipset as the D600.

Edit again...

Some bad news - reading the chart for the TE4302 chip, it runs at the 100mhz speed, so at least for the D600, it is a waste of money to buy the UHS-104 spec cards. Again, I am guessing that will be the story for the D7100.

David

"Extraordinary claims require extraordinary proof " - Carl Sagan

A general, generic topic D7100 buffer guesstimates [View all] , jbloom Gold Member Awarded for the continuous and generous sharing of his high level expertise and his always encouraging comments in several forums. Donor Ribbon awarded for his generous support to the Fundraising Campaign 2014 , Mon 04-Mar-13 02:08 PM
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     Reply message Compressibility could be a big variable...
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          Reply message According to IR the D7100 supports them...
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                    Reply message I'm going by Nikon's numbers here...
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