Advise please

[russellsnr2]

Hi, Please can someone explain this for me.
I have purchased a second hand Sigma super wide (that's what it says on top of lens along with 1: 2.8 & 1.28mm)
Does this 1:2.8 mean that the camera HAS TO BE SET AT 2.8 for the lens to work as if I try say f22 I get an error99 message, set at 2.8 & camera fires, but I am a bit confused as I understand it, most wide angle lenses are used in Landscape photography but I thought a setting of say F22 would give better results than set at F2.8.
Also is it better to use a skylight or a polariser for protecting the lens.

[DocFrankenstein]

Seems like its an old lens which isn't compatible with your new camera.

Sorry.

[Monito]

I advise using meaningful titles to get the most appropriate people attracted to your thread who can help you. You can edit the title with the Edit button.

[Jon]

Many older Sigmas wouldn't work with the newer EOS cameras since Canon never released the specs for the camera-lens interface and Sigma had to reverse-engineer it. This meant that as Canon started to implement new features the older lenses wouldn't work. Sigma, to their credit, offered to re-chip those lenses they could to make them compatible. It's worth contacting them to see if your lens is one they can fix.

For lens protection, if you use a polarizer you'll be giving up 2 stops. Skylight filters have a very slight pinkish cast that may affect colour reproduction on a digital camera. A good UV filter will have negligible effect on the exposure or colour rendition. Poor quality filters (of any type) may add flare and/or distort the image, so make sure you get a good (B+W, Tiffen, Hoya) multi-coated filter regardless of what type it is.