I recently purchased a Canon 6D....

[PhotosByNeva]

I wanted to upgrade from my Rebel. I have several lenses already and noticed that when I use them on my 6D there is a round black ring around the outside edges. Upon reading it seems that the Rebel has a "cropped frame" and the 6D has a "full frame". Does this mean that I have to get all new lenses to use with my 6D, and make sure they are EF?

[lly3988]

Please buy and use only compatible lenses on your cameras.

Compatibility is important. If you are not sure, use only Canon EF lenses on your 6D. (in the case of your 20D, use both EF and EF-S lenses)

Don't just buy any lenses if you are not sure. Don't buy third part lenses if you are not sure.

Do some researches and start from the very basic. Kit lenses are something not bad. e.g. EF24 105 and EF 24 70 F4. Buy a cheap 17 40 F4 and you have covered from UWA to short tele.

Good luck.

New Tamron and Sigma lenses are very good too but they are not cheap. Some have AF consistency problem and may not be as stable as Canon lenses.

[PhotosByNeva]

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@lly3988 wrote:

Please buy and use only compatible lenses on your cameras.

Compatibility is important. If you are not sure, use only Canon EF lenses on your 6D. (in the case of your 20D, use both EF and EF-S lenses)

Don't just buy any lenses if you are not sure. Don't buy third part lenses if you are not sure.

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Apparently you did not read the whole thread. My lenses were fine and compatible with the two cameras I did have. The problem was that I upgraded to a 6D not realizing that it was a full frame as my other two were cropped frame.

I appreciate your advice, but I am going to have to get lenses that are made for my 6D now.

[ebiggs1]

New Tamron and Sigma lenses are very good too but they are not cheap. Some have AF consistency problem and may not be as stable as Canon lenses.

This is not completely accurate. You should always buy Canon lenses unless there is a compelling reason not to.
Price could be one but no Canon equal is the biggest.
The newest line of Sigma anf Tamron are extremely well made and compatible. If there is a problem they can be re-chipped. The new 'Art' series of Sigma can be configured with the unique USB dock.
Most new Sigma and Tamron can even have their mount changed to a different brand.
Don’t rest on the past where there were plenty of issues with them. To the point where I would not touch one.

[PhotosByNeva]

I don't think it was a mistake as I wanted to upgrade to a better camera as I'm planning on taking my photography farther. But had I known this in the long run I probably would have been buying different lenses. It was my own fault because I knew there was a difference. I had read it before but it's been quite a while.