Hi EOSophiles,

I am trying to get hold of an “eyepiece” to put on my telephoto lenses, in 
place of the camera body so that I can use them as telescopes, in order to 
save weight (not to mention money) when out photographing & watching 

My first question is - does anyone know where I can come by such a device in 
a Canon EF fit? WJM has told me that he has seen such items advertised in 
the past but not recently.

I have obtained a “Minolta Lens/Monocular Converter” & found a company 
called SRB Film in Luton, England who are very helpfully prepared to convert 
the mount on it to Canon EF but I would also like to be able to take 
advantage of the image stabiliser on my 100-400. I found the lens contact 
pin-out details (below) on WJM’s site but I am not an electronics expert. 
Can anyone tell me what is likely to be needed to turn on the IS?

Martin Wiseman wrote the following on 10/8/98:

“Looking at the front of the camera body and reading from left to right, the 
signals are:

2. P-GND
3. P-GND
4. VDD
5. DCL
6. DLC
8. D_GND

Pins 2 and 3 are combined into one large contact on the lens. My 
interpretation of these signal names is as follows:

VBAT    - Battery power for driving motors etc.
P_GND   - Power ground - the return path from motors to battery negative.
VDD     - Power for the logic circuitry
D_GND   - Digital ground for the logic circuits
DCL     - Data from Camera to Lens
DLC     - Data from Lens to Camera
LCLK    - Data clock

Other people have suggested that the data protocol is probably 8 bit serial 
at 62.5 kHz and possibly based on the Motorola SPI interface.”

I have not tried simply putting 6 volts across pins 1 & 2 yet but I imagine 
that there will be something more complicated than that needed to activate 
the IS.

I have mailed MW who says that this may work however, especially if I add 
the correct data voltage across pins 4 & 8: Since early bodies were not 
aware of IS there can be no signal specifically sent to activate the IS but 
there may be a general “wake-up call” sent to the lens. Does anyone know 
what data voltage is used, to save me much effort with my multimeter & 
trying to fool my EOS 3 into believing the lens is on when it isn’t?

WJM has suggested using the Novoflex Lens Reversal Adapter (that maintains 
electrical contacts to the lens when it is detached from the camera body) & 
using the camera body itself to activate the IS. This would certainly do the 
trick, however it would be a bit cumbersome for bird watching to have the 
camera body suspended nearby all the time, & the eyepiece would have to be 
used with the Novoflex adapter even on non-IS lenses because it would have 
to be suitably shortened. I would far prefer to find out what signals need 
to be sent to the lens to switch the IS on, & try to incorporate a battery & 
a device to give these signals into the eyepiece, or mounted on it.

Anyway, this is all I have managed to find out so far & I would greatly 
appreciate it if someone can enlighten me further before I risk blowing up 
my treasured IS lenses! Can anybody help please?

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