Speedier Tethered Shooting
The main reason for choosing to shoot tethered is that it can help make the import process smoother and faster. There are a number of factors, though, that can affect the overall tethered shoot import speed. The first thing you need to consider is the camera interface. Professional Digital SLR cameras should boast a faster buffer capacity and data transfer rate compared to budget digital SLRs. Early pro cameras like the Canon EOS series used a FireWire interface, whereas more recent cameras now use USB 2. Both are capable of providing reasonably fast data transfers, but the actual download speed may be compromised by two further factors. One is the speed of the operating system FireWire/USB drivers and the other is how well the software is able to optimize the interface connection. In the various reports I have read and the personal testing that I have done myself, it is clear that different combinations of software and operating systems can make a significant difference. You also have to consider whether you are going to shoot raw of JPEG and the likely size of the capture files.
Whenever I carry out a speed test I usually time how long it takes to download a burst sequence of ten captures and build a full set of initial previews. I then divide the total number of megabytes for all the captures by the time taken to fully download them. This gives me a rough idea of how fast the tethered shooting speed is in terms of the number of megabytes per second to download the files from the camera and build the initial previews. My previous experiences with the Canon EOS Utility were quite interesting. I discovered that running EOS Utility plus Lightroom via Windows XP on my Intel Macintosh was around 4–5 times faster compared to running the EOS Utility plus Lightroom via Mac OS X 10.5 on the same computer. More recently I have found that with the later versions of the Mac OS X system, the speeds are more comparable, and if anything, the Mac OS X download speeds are now faster. For example, using a Macintosh with a 2.8 GHz Intel chip and 4 GB of RAM running Windows XP, I have been able to achieve download speeds of up to 8.4 MB per second when capturing images via EOS Utility and auto importing them into Lightroom 3. Using the same hardware running Mac OS X 10.5.7 I have been able to achieve download speeds of up to 9.6 MB per second. These are perfectly respectable download speeds. However, when capturing images directly via Lightroom 3 using the new Tethered Capture feature, I have found I can download images at speeds of up to 10.8 MB per second using the Mac OS X 10.5.7 system. This is in line with what one would expect. Having the ability to download images directly to the destination folder is obviously going to be faster than downloading the photos to a watched folder and then having to move them to a new folder location.
One note of caution here: having a camera tethered to the computer can quickly drain the battery. If you find this to be the case, then remember to switch the camera off between shots. Another alternative is to use a DC power supply to power the camera while working in the studio.