ImageCreator Loc: Northern California

I have the 5d3 and have four lenses, three are L's--24-105, 16-35, and the upgraded 100-400 II. A 100 macro that is not an L. With the three L's I can cover every situation. My experience is total satisfaction with the 5d3 and lenses.

Anandnra Loc: Tennessee

The 5D3 will get you the best bang for the buck. Best all around camera for the optimum price (with the choices you are looking at).

Blurryeyed Loc: NC Mountains.

I think that the 6D has better ISO performance than the 5D mk III, but other than that the 5D has a lot more features. I have a 6D and it feels like a stripped down version of my other Canon bodies which is just fine with me, the quality of the images is excellent.

BTW, I don't think that you will be able to use the Sigma 10-20 on your full frame, if you are going to look for an ultra-wide I would recommend the Tokina 16-28 for your camera if you can live with not using filters, if you need filters then you might consider the Canon 16-35 either version, the f/4 is cheaper and sharper.

I went through 2 different ultra wides prior to purchasing the Tokina, one was the Canon 17-40 which I was really disappointed with, but the Tokina is very sharp, has a fast f/2.8 constant max aperture and still costs less than any of the Canons.

mikedidi46 Loc: WINTER SPRINGS, FLORIDA

I am like you right now. I have Canon glass, and I want to move to FF. For me, based on what I do when I travel the 6D is perfect.

Grnway Loc: Manchester, NH

Hi Digikid,

From the description of the glass that you own, the canon lenses will work on a FF, so you've got that going for you to remain in the Canon direction. Can't speak for the Sigma.
I own both the 5DIII and the 6D. I prefer the 5D all the time, but if you're on a budget, the 6D will work nicely. It's lighter, simpler and takes beautiful photos.
The flip side is that the 5dIII prices have come down a bit with the intro of the 5DS, etc.
Decisions....decisions.....

LFingar Loc: Claverack, NY

When you balance cost against capability, the 5DIII is the winner, IMO. If cost is a major concern, then the 6D will give you the most bang for your buck, if you are willing to accept some limitations. It has no weather sealing, only one card slot, and a less capable auto-focus. You can shoot action with it, but that is not what it was designed for. You have to work harder for decent results, and you will almost certainly miss more shots. For non-action shots it will do as good of a job as the 5DIII, IMO. The big advantage of the 5Ds is resolution, from what I can see. Your ability to crop and still produce a high quality image is the best of the three. The downside is that to use the camera to it's full potential you need Canon's newest (and most expensive) lenses. The max frame rates for the 6D, 5DIII, and 5Ds are 4.5, 6, & 5 respectively. Not a tremendous difference. If you want the latest and greatest, and don't mind the cost or working with huge files, then the 5Ds is probably what you want.
Wanting the best and needing the best are two different things. How you use your camera and what you do with the images are big factors. If you are like most of us, the 5Ds is probably vast overkill. Like hunting squirrels with a 30-06 when a .22 will do just fine.

Peter from NH Loc: Dublin NH

I can't imagine wanting to shoot sports with a 6D. I tried. The number and quality of the focus points is just way too limiting. Too many soft shots when the subject isn't in the center of the frame.The 6D is a good though limited camera. Fine for landscapes but not the camera I want to have in my hand with any kind of spontaneous movement.

Frequent Flyer Loc: Kujukuri, Japan

You didn't say what kind of Canon lenses you have. Are they EF which will work on full frame or are they EFs which will not work on Canon full frame cameras. In the latter case it's practical to consider all full frame brands. Next you just said you want to shoot full frame. If you want to shoot like a pro you want to shell out for the 5D3 or the newest 5s, but if you just want great landscapes and portraits and less than pro sports photos the 6D is all you need. I moved from a 7D to a 6D for the full frame, and I shoot surfing, family and landscapes as a beginning hobbyist.

izzyuno

I just recently purchased the 5Ds camera only to find out that I cannot use my EF S (mount) lens on the full frame 5Ds camera. You have to use EF (mount) lenses. The EF lenses are backward compatible but not the other way around.

Wendy2 Loc: California

If you have a 10-22mm there is a fix. And maybe there is a fix for the others based on this fix, I don't know. If you do have that lens, let me know and I will post the link showing you how to do it.

jeep_daddy Loc: Prescott AZ

Really? You didn't ask someone if your old lenses will work before you spent your money on a full frame body? That's a shame. I guess you'll be selling some lenses and spending some money on new lenses.

LFingar Loc: Claverack, NY

EF-S lenses are not designed to work on any full frame Canon. No matter which of the 3 bodies the OP chooses this will be a factor.

RRS Loc: Not sure

Well one camera can do everything when you only have one but two can do it much better. The 5Ds makes a very good studio body but if it's ISO expand ability and sports you want I think the 5Ds misses the boat in both of those categories. The 7D MK II will beat the pants off of the 5Ds in that regard. As for your ambitions as a professional photographer in architectural and real estate they are closely related but sports is another ball game entirely. For building your business a 5D MK III and a 7D MK II would cover all the bases. Just my thoughts from over 25 years of being in the business of photography. If you haven't looked at the 7D MK II please do yourself a favor, it's your money.

Peter from NH Loc: Dublin NH

I have that combo (5D mk III and 7D mk II) and have no envy of anyone else. Really great combination.

anotherview Loc: California

Now you know what other experienced Canon users know.

Most if not all ads for the Canon EF-S series of lenses say clearly that they work only with the Canon cameras having cropped sensors.

Note that you can, as a rule, return a piece of gear to the seller if unsatisfied with it.