Electronic First Shutter Curtain

Anyone who has gotten serious about extreme macro photography (photomicrography) has had to get serious about dealing with vibration. Once basic things such as using a sturdy stand, employing camera mirror lockup, and using some kind of remote shutter release have been dealt with, the motion of components within the camera becomes a significant concern.

I am doing my shooting with a Canon 5Dii. My partners are both using Canon Rebel 600D (T3i) cameras. It turns out that both of these camera have the ability to start an exposure without using a mechanical shutter. This feature is refered to as "electronic first shutter curtain".

The way this works is that when the camera is in live view mode, and the feature is active, an exposure is initiated electronically rather than by moving the mechanical first curtain. The reduction in vibration is dramatic, as demonstrated by test images taken by Charles Krebs and discussed in this article

It turns out that this is how all Canon Rebel Cameras work all the time when in live view mode - so you get this whether you like it or not. In my case, with the 5Dii, this is an option called "silent shooting mode" by Canon that must be activated in the camera setup menus. It has been speculated that in any case, this is a feature invented for the niche market of photomicrography, but labelled as a feature to appeal to the average camera user.

There are some caveats, mostly dealing with use of electronic flash. In a nutshell, this feature does not work with flash. The way people using flash deal with vibration is to use second curtain synch, dark ambient, and long enough exposure times to let any vibration die down by the time the flash triggers. With a Canon ETTL flash, the ETTL preflash can only be monitored with the mirror down. For some reason, with non-canon flashes, the camera will not trigger the flash when the camera is in live view mode and an exposure is triggered.

So why not an electronic second curtain you ask?
It boils down to this. You need a mechanical second curtain to cover up the sensor, then the covered sensor has the image stored in it and can be read out after the exposure is done, which takes some time. It is possible to electronically clear out sensor rows to start an exposure, but there is no way to electronically make the sensor insensitive to light and still retain the image.

Magic Lantern

Something else to explore is the possibility of changing firmware in your camera. The Magic Lantern project has developed alternative camera firmware that is worth taking a look at.

I have often wondered what could be done about just saving one of the images being transmitted via USB during tethered live view. Clearly there is no shutter activity going on, but I suspect this operates at resolutions subsampled from full sensor resolution. I have read hints that this can be done (perhaps at full resolution) using the Magic Lantern firmware.

Feedback? Questions? Drop me a line!

Tom's Mineralogy Info / [email protected]