The Problem
The most recent release of the mac operating system broke the ability to tether FireWire based dSLRs, most notably the Canon 1Ds II to Capture One Pro, but the fix is very easy. The reason for the problem is that Apple included a program associated with Apple’s photo program Aperture, which interferes with Capture One’s ability to connect to the camera.
The Symptoms
ALL 10.5.X and 10.6.X computers require the short-term or long-term fix below to ensure proper and stable tethering to a 1Ds II or 1Ds I or other FW based dSLR. Do not wait to see if you have symptoms of the problem; at some point you will. However, for the sake of completeness the symptoms are: random disconnects (often during the transfer of the first image), failure to connect, or extremely slow transfer of images with the failure to connect at all being the most common symptom.
The Short-Term Fix
1. Open [Hard Drive / Applications / Utilities / Activity Monitor]
2. Select the process Type8Camera and push “Quick Process”
This will allow the camera to tether to Capture One until the computer is restarted.
The Long-Term Fix
With the dSLR disconnected:
1. Open [Hard Drive / System / Library / Image Capture / Devices] and copy the file “Type8Camera.app” to a different folder (e.g. your desktop) as a backup.
2. Delete the file “Type8Camera.app from the Devices folder.
3. Restart the computer.
This will prevent the problematic program from launching and permanently* solve the problem. It will also prevent Aperture from tethering to your dSLR.
Update: It appears that 10.6 requires this same fix. It also appears that several major updates (e.g. 10.5.7) restore this file even if you have previously deleted it.