The α700 is one of the first cameras that comes with an optical remote control accessory – the “Remote Commander” for not only shutter trip, but actually playback control of the camera. It removes having to handle the camera during a playback on a monitor or television. That's quite useful, but that device is NOT involved in this discussion. This discussion concerns using the "tethered" USB control of the camera.
When most people consider "tethered" control of the camera, it is typically through the rather "limited" 5-foot Standard USB-A-type port-to-A700 USB mini-port cable. That does NOT give you a lot of room between the camera tripod or other camera holder and the PC. You can safely add another 10-feet, usually, by using a USB Male-A to Female A extension cable.
This idea came up as a side-by-side concept when dealing with timed shots, using a Timer Remote Cord. The “timer cord” will cause the Alpha-camera to focus, between each shot, using whatever Focus Area mode you previously selected.
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The α700/α900 USB-tethered mode provides almost complete control (exposure -> duration, aperture, ISO, White Balance, DRO, Drive mode, Quality, Image size, Aspect ratio (all modes) over the shot, with the PC offering not only real-time control over the camera, but an image transmitted directly from the camera to the PC. The PC also collects the image directly to where ever directed (hard drive, CD, etc), instead of storing it on the memory cards (CF or Memory Stick). In that way, if the camera should be compromised, your collected image data is not subject to being lost, also. (BTW: You must have a memory card in the camera, otherwise the "USB-connection" hangs on the camera and will require a complete power down (battery removal) to clear it)
The SONY's "tethered" application also displays the camera's battery condition (only the #1 battery when the vertical grip (VG-C70AM) is used), which will be very helpful, because I suspect that this idea, if it is viable, may be a significant drain on the power resources. An AC-VQ900AM AC Adaptor/Charger can be used to power the camera indefinitely ... you just need a 150 ft (or whatever length) power cord to get power out there, too.
By using a “USB Extender" (see image below), you can extend the normal USB 15-foot limitation to a full 165-feet. That makes for some exciting possibilities.
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Going on step further, with this extended reach, purchasing a robotic pan/tilt tripod head ... also controllable by USB from Eagletron ($179) allows you to orient the camera through use of the same setup, as the "USB Extender" has a very convenient second USB-cable port on the "remote" end
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and allows for two separate USB devices to be serviced.
In this case:
1) The A700
2) The USB Pan/Tilt Robotic tripod head (<- click on this link)
With it, you can zero-in on those subjects, progressively align the cross-hairs with test shots and then ... make history!
It is at this point that you can truly appreciate having a heavier tripod.
Well, obviously you could not have this with a 35mm-film setup or even the intro-level Alpha DSLRs. You would have been left to an electronic timer and just waiting the subject out and having a series of arbitrary shots. That usually consumes film at an awful rate. It is only because of the advanced electronic nature of the gear that this is even possible, when you can actively control and monitor the results. No wasted processing time, other than your review of the digital images.
Now, admittedly, you could combine a “timer cord” and the old version 3 Remote Control application features of the α700, so you could walk away from the remote control and allow the timer cord to just do its job and then, as it gets darker, as the sun sets or what not, you could revisit the remote control to make setting adjustments, unless the camera was in AUTO, but that can be rather dubious.
The new α700 Rev. 4 update builds an interval timer feature into the Remote Control program, so you do not necessarily need the “timer cord” ... but the restriction that is only will work if drive is set to SINGLE frame shots. Also, no shot faster than every 10 seconds is possible with the software. If you want bracketing, it will not allow the DRIVE mode necessary, and that is specifically where the “timer cord” would step in, because it is independent of the Remote Control program.
You also need to realize that AUTO mode has a limited amount of flexibility ... whereas Manual Mode is the true control. Also, once the camera is in AUTO Mode... you really have to make a trip out to the camera to change it. In AUTO you only have the limited +/- EV and +/- flash compensation, although you still can control ISO by the remote control program. Your aperture and shutter speed are whatever the camera's exposure algorithm has in mind.
All in all, the remote control coupled with the robotic pan/tilt offers some powerful and exciting reach to the A700. It is definitely worth a look and comes in at about $300 total for the USB extender, the robotic pan/tilt head and 150-ft of Ethernet cable you will need.