Has anyone compared the transfer speed of a camera's internal USB reader, to the transfer speed of an external USB reader ?

"We timed the USB transfer of a maximum-resolution file at 3.7 seconds for 849 KBytes. That translates to 229 KB/second, a very reasonable transfer rate for a 2 megapixel digicam"

This quote from a review of the Sony 505 does not sound much faster than a serial transfer. And it falls well short of the advertised 1Meg / second transfer rate of external readers.

Anyone with some hands-on comparisons available?

-- John Forristal (johnforristal@hotmail.com), December 15, 1999

Answers

It may be a bit off topic, but 229 KBYTE/sec. is actually quite a bit faster than serial transfers which are usually limited to 56,115.2 or at best, 230 Kbit(Kb), NOT KBYTE(KB), per second. 230 Kbit/sec serial is actually about 23 KBYTE/sec, assuming 8 bits per byte, no parity and one start and one stop bit per byte.

By the way, USB is actually rated at 1.2Mb/sec... Yes, mega-bit, not mega-Byte again... :-) They just love to confuse people with jargon and like sounding terms in those "USB: the best thing since sliced bread..." ads. ;-)

Not to rain on any parades, but the absolute best theoretical case on standard USB is 900KByte/sec according to some documents on the web site that specs and governs the USB specification. That's only theory, though. Actual performance figures usually seem to be much lower, and often only a bit higher than parallel port card readers which seem to work at about 550 KBytes/sec. Frankly 550KB/sec is pretty fast, dumping about 8MB to disk in 15 seconds.

As you might imagine, I'm a hold-out with a Lexar Media parallel port based smartmedia card reader. :-) USB looks good on paper, but doesn't seem to yield as much as promised. Firewire or USB2 may be much better. In fairness, USB is the connectivity champ so far, it's hard pressed to be a speed demon too...

Still and all, if you have USB ports that already work with your operating system, USB is not a bad way to go. At 229KB/sec it's only a 35 second wait for 8MB's of images! It certainly beats the 20 minute long serial port download time for 8 MB with my camera.

-- Gerald Payne (gmp@francorp.francomm.com), December 16, 1999.

I have a Casio 2000ux with USB and it will dump 8MB in about 15 seconds. USB is so easy - I just leave the cable connected and when I want to get a photo into the computer, I connect, turn the camera on, and the computer recognizes it in about 2 seconds as another drive.

If I go to a friend's house, I bring the USB cable a floppy with the driver on it. In minutes, I can install software and load photos on any system with a USB port.

USB is the best!

Tom

-- Tom Lovely (tlovely@mediaone.net), December 17, 1999.

While the USB bus has a bandwidth spec of 12 Mbps (1.5 MBps), control overhead limits actual data throughput to approx. 900 KBps.

I benchmark tested a Microtech Cameramate card reader, with an Olympus 32 MB smartmedia card, at 740 KBps.

A real-life transfer of 29.9 MB worth of 37 images took 67 seconds. This comes out to 467 KBps.

-- Sean Collins (sean@hogheaven.com), December 17, 1999.