download speed?

[J_ph]

I do shoot Raw+Jpg so I know that I'm straining the system. The CF cards that I use aren't the bottle neck, because it seems that I can shoot without the camera waiting to pause if it's not tethered.

The bottleneck is the USB2 throughput, my Macs USB2 is painfully slow but the USB2 on the PC is much better, although it can't keep up with the pace of active shooting.

Is there any slowdown due to the application that is transferring the images, and does DslrRemote work at the same pace as EOS utility?

thanks, j

[DavidB]

My use of tethered cameras has only been on experimental basis, but, as these are mostly more general questions, I'll have a go at answering.


I do shoot Raw+Jpg so I know that I'm straining the system. The CF cards that I use aren't the bottle neck, because it seems that I can shoot without the camera waiting to pause if it's not tethered.
The camera has its own dedicated processor and, usually, a pretty large image buffer. Once the buffer is full (typically only in continuous shooting), the frame rate reduces dramatically. How the camera works in tethered mode will depend on its firmware, but I suspect that you are right and that downloaded images bypass the CF card.


The bottleneck is the USB2 throughput, my Macs USB2 is painfully slow but the USB2 on the PC is much better, although it can't keep up with the pace of active shooting.
I'd expect this, because downloading from a camera is typically a lot slower than downloading from a card/reader. To add to the complexity, USB hardware, cables and drivers can be very variable; changing the USB port to which you connect can also sometimes make a significant difference, and the conventional view is that you should not connect high throughput devices via a hub.


Is there any slowdown due to the application that is transferring the images, and does DslrRemote work at the same pace as EOS utility?
For Canon cameras, I believe that DSLR Remote Pro, like other Breeze applications, makes use of Canon libraries, so I would expect the performance to be similar. But the best advice is to download a trial and experiment.

Hope this helps.

[J_ph]

thanks for the response. I do use DslrRemote and it's great. I was just wondering where I can improve on the transfer speed. I found the following info:


53 seconds to transfer 117 MB (54 files) with Lexar 40x.
2 minutes to transfer 267MB (114 files) with 2GB SanDisk Extreme III

2-1/4 minutes to transfer 222 MB (245 files)

7-1/4 minutes to transfer 800 MB (400 shots) from a 2GB SanDisk Extreme III

That's too darn long. Shot on and read with the Extreme IV cards and reader, 800 MB should transfer in 34 seconds, not seven minutes. The 53 seconds required to download 117MB should only taker 5 seconds.

These speed limits are caused by the camera, not the cards.

http://www.kenrockwell.com/canon/5d.htm

I've done a bit of testing of the USB speed on Macs (horrible) and concluded that PC's were the way to go with tethered work, and now following up to continue in the pursuit of speed, it appears that I will be stuck with the status quo until the 1DsMIII appears with possibly a faster throughput.

regards, j

[Chris Breeze]

It's usually the speed of the camera's USB interface that is the limiting factor.

Most cameras take approx 2 to 3 secs to download each image and with the latest models this doesn't seem to vary much whether you shoot raw, JPEG or raw+JPEG. If you trigger the camera from the PC the Canon libraries won't let you take another picture until the current one has been downloaded to the PC or saved to the camera's memory card. If, however, you take pictures using the camera's shutter release you can keep shooting until the camera's internal buffers fill. The downloads will lag behind a bit, but you can keep shooting.

[J_ph]

>If, however, you take pictures using the camera's shutter release you can keep shooting until the camera's internal buffers fill. The downloads will lag behind a bit, but you can keep shooting.

I generally shoot from the camera, either because of the mirror pre-release forcing the use of a cable release, or because it's live action. On occasion it seems that I do reach the point of the buffer filling and where the 5d will not allow any more photos.

Unfortunately after a little more investigation, the 5d has a buffer to accomodate 17 raw images and the new 1dsMIII will accomodate 12 raw images. So, unless the firewire yields an advantage or they have some other magic to speed up the throughput I may actually wind up with a bigger bottle neck than my current workflow. ( a small penalty to pay for getting 21MP in a 35mm body, yikes..... but I will definitely wait for them to reach the first line of testers before placing my order.)

regards, j