Previous lens or filter adapters for the Canon G Series had some big compromises. Then in 2010 Canon released the FA-DC58B which unusually moved with the lens. It does this by having a spring mechanism. When the lens is at wide the adapter does not extend. When the lens is moved to telephoto then the adapter extends with the lens and using the spring mechanism retracts when the lens is set to wide. This is quite clever.
At wide setting the lens barrel does not contact the adapter. Note the plastic filter threads. The adapter is all plastic construction and is very light. It does not unbalance the camera and in fact it is quite comfortable to hold the fixed part of the adapter like holding a mini DSLR.
The lens adapter retracted. Although it does extend slightly below the camera body and the camera does not sit flat the camera stands properly and does not fall back.
The lens adapter fully extended. It is smooth in operation and there is no suggestion the lens motor is strained.
The low light focusing light appears slightly obscured by the adapter but the main part of the light is not obscured. It appears to work correctly.
On camera flash is blocked by the adapter at wide and also this continues towards telephoto where eventually it is not blocked. It is unacceptable so a flash gun such as the 270ex is recommended.
At macro the flash is also blocked. This is the only real problem because using a flash gun is not easy for macro. It may be too bright or too high. I am waiting on my 270ex to arrive so i can test this out.
Using a Hoya Pro 1 Digital filter there is not vignetting at wide.
I purchased this filter adapter because I use the G series cameras for my job which is in a dusty environment. I have sustained both G10 and G11 cameras getting the lens or lens doors stuck from dust. Additionally I would rather clean a filter rather than the lens all the time.
I think the macro flash problem will be the only issue for me, along with having to remove the lens cap every time which is not a real problem. I am quite pleased with this unit.
Filter thread is 58mm