7D Mark II USB slow transfer speed

Started Jul 25, 2016 | Questions thread
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Woodbird New Member • Posts: 7
7D Mark II USB slow transfer speed

Usually I transfer image through Macbook Pro's builtin SD card reader or an Lexar CF card reader (USB 3.0). Recently I started experiment with the USB cable and noticed that the transfer speed is very slow.

The SD Card is an SanDisk Extreme PRO XC1, UHS class 3, class 10 card, 64GB, with 95MB/s rated speed.

The CF card is an SanDisk Extreme PRO UDMA 7 card, with rated 160MB/s speed.

The computer is an MacBook Pro Retina 2014 model, with SSD drive

I tried a few methods of transferring the the images,

Using Lightroom "Import",

SD card through builtin card reader: 70MB/S

CF card through Lexar card reader: 105MB/S

Copy images directly in Finder,

SD card: 90MB/S

CF card: 120MB/S

I also tried image capture and other photo importing programs come with OS X, and the speed is either on par with Lightroom or slower.

In contrast, when connecting the camera through USB, the transfer speed is noticeably slower, using either lightroom EOS utility (2 or 3), or Image capture. I cannot find the actual read speed. But the disk write speed during transferring is never above 40MB/s and most of time about 30MB/s. I manually timed the transferring, and speed is roughly at this range.

USB 3.0 should be capable of much faster transfer rate. There are a few reasons I can think of for this slow rate observed.

1) I have a faulty camera

2) Canon is so stupid that the in camera read speed is severely limiting the transfer speed.

3) Software issues. This is rather unlikely.

Does anyone observe similar issues? If is the norm, then I think I can rule out the first reason and move on.

This question has not been answered yet.
Canon EOS 7D Mark II
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