Aperture Control Canon EF

S

shred444

Active member
I'm looking into building/purchasing my own 35mm adapter.

One of my main concerns is adjusting the fstop on the lens. It is my understanding that by default the canon lens are wide open (ie. f/1.8). When they are connected electronically to a Canon SLR, the camera will communicate with it to adjust the Aperture settings.

If no SLR is available, and the DOF is too shallow, how can the lens aperture be adjusted?

How do Nikon lenses compair when dealing with this problem?
 
So it looks as if the EF lenses use SPI to communicate to and from the body. And it also looks like that protocol is not open source.
 
Excuse my english!
"It can't be."
It's impossible to do it if you don't know what are you talking about. There are 3 ways to control the aperture on a canon EF lens.
Here they are:

http://www.letusdirect.com/35mm-lenses/766-canon-ef-lens-aperture-control.html
http://redrockmicro.com/forum/viewtopic.php?t=3137

or you can do a google search, there is an adapter that can do it for you, it's very expensive, 1000$, but if you own a lot of EF-S lenses, and don't want to change to nikon, worth the money! I don't remember their website!

I hope this help!
 
chrmad said:
Excuse my english!
"It can't be."
It's impossible to do it if you don't know what are you talking about.
Click to expand...

None of the links that you provided show the OP a way to change aperture without an SLR camera body attached, which is what he was asking. The Novoflex solution essentially allows you to change iris without removing the lens from the camera, which is an improvement, but an SLR body is still needed to provide the necessary control.
 
I've purchased a canon EF12 Extension tube which passes the electrical connections through between the body and lens.

I'm going to hack apart that connector and probe out the communication line between the camera and a lens to see whats going on with the SPI commands.

If I can decipher the commands, I can reprogram an external microcontroller to mimic the body of the DSLR, therefore allowing aperture controls and internal focus as well.

sounds snazzy
 
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