You can see how the full frame is going to smear the edges. This is just a crop.....not a true square. It is going to take some shooting so the lens can tell me what kind of subject matter it wants.
There is one other issue. I haven't been able to figure out how to adjust the exposure except a -2 exposure compensation. Changing the aperture doesn't change the exposure. Changing the ISO doesn't change the exposure. This is on the 5D. I've been told that both of these adjustments work on the 20D with the Holga lens cap. When I get back to San Miguel, I'll see what happens on the Canon 10D but then I have to contend with the 1.6 lens factor.
Update: Finally had time to play with the lens on the 5D some more instead of slapping it on and rushing off to take pics. I was starting from the assumption that the lens was f8 but it isn't. It is f4-f5.6. So now I realize that the metering does work and I can adjust the ISO as well. Duh!!
And once again I apologize if the tonal range and color are off. I just can't tell on this laptop monitor so I'm trying to work with the numbers in Photoshop.