Not sure if the problem existed before the meltdown. I did not have a lens appropriate for interior real estate photography until recently. You are probably right about not mentioning using third party lenses to Canon.
My "work" camera is a 3Ti with articulating LCD screen and 10-22mm Canon ultra wide angle. That model is only capable of bracketing 3 at a time. I use Photomatix to merge the files. Using three does not give me enough highs and lows to get clarity outside windows. I normally bracket a minimum of 6 frames, but frequently bracket 9 and 12. I shoot manual mode using f-8 to f-13 with ISO locked at 100. The shutter speed is varying to get the over/under exposures. The attached photo is using the 3Ti and 10-22mm and was made from a minimum of 9 frames.

I already owned the 5DIII and wanted to incorporate into some of my work because of it's ability to get a huge spread on exposures with 7 brackets and never touch the camera on the tripod. The Tamron 15-30mm on a full frame gives a wider angle than the 10-22mm on a crop sensor and it was an affordable option.

TriX, the best ultra wide angle lens for a crop sensor Canon is the Canon 10-22mm. This is my everyday rig.
The best ultra wide angle lens for a full frame Canon is the EF 11-24mm which weighs in at a hefty $2,700. This is why I bought the Tamron.

speters, looking at all the issues this camera has had, and the number of times it has gone back for repair, a lemon is my only conclusion. Last year I was using a SanDisk 128 GB CF card. I bought a Lexar 128 GB and used it for a few months without a problem. I put the Lexar card in one day and it fried the camera electrical system. B&H replaced the card. The new card caused the same problem. I called Canon and they told me to call Lexar. I spoke with Lexar. They replaced the card and I had the same problem. I sent it back to Canon for repair after I did a full camera reset, a procedure I got from a Canon tech a long time ago. That didn't help. Canon repair called and told me they thought it was a bent prong in the CF slot and they would fix it...as a courtesy. Really? They couldn't explain why the SanDisk CF card worked just fine in the camera. This has lemon all over it and Canon just wants to pass issues off to someone else. I am very disappointed.

Love the story about the ray gun light meter!
I brought this 5dIII and Tamron SP 15-30mm lens to a shoot yesterday. It performed just fine for all the 7 bracket interior shots I needed.
I brought it outside for some exteriors and it choked on brackets after 4 or 5 every time.
Took it to a shoot today, wouldn't bracket at all.

I was disappointed that Canon was so dismissive about the bracketing issue, blaming the lens manufacturer. B&H recently offered a package that included a 5DIV with a bundle of either Rokinon or Tokina lenses. If the third party argument had any merit, I doubt B&H would be offing this package.

I did put a Canon 24-70mm f-4 on it and it did work.
The fact that sometimes the camera will bracket and sometimes will not is where I believe the issue is.
It seems there is always a new problem with this camera. Two months ago, it would continue to fire until I shut the camera off. That seems to have corrected itself.
So now the latest is bracketing.
There is no doubt in my mind this camera was assembled on a Monday and is a lemon. I know a number of people with 5DIIIs who have never had an issue of any kind.

I have a Canon 5DIII that I bought about 1 1/2 years ago. In the first year, I had to send it back to Canon for repair 3 or 4 times with completely different issues each time.
Of course, it is now out of warranty.
The newest problem is that it won't shoot a run of 7 bracketed photos, and chokes after 4 or 5. No images are saved to the memory card.
I wanted to include this camera body in my real estate photography work, but need a wide angle lens. The Canon wide angle for this work costs $3,000, so I looked for a less costly lens solution. I purchased a new Tamron SP 15-30mm f-2.8 lens. Great lens, although a bit heavy.
The first few times I used this lens, the 5DIII did a great job bracketing 7 shots, and I was pretty happy with the images.
Then, it stopped completing all 7 brackets.
I called Canon support. They argued that it was due to using a third party lens and I should talk to Tamron. I argued that I put this lens on my 7DII and it bracketed 7 shots perfectly.
Canon said that didn't matter and it was due to using the third party lens.
I did call Tamron and they suggested I try a different memory card. I did and it made no difference.
Has anyone else had an issue with shooting brackets with a 5DIII?

Hi Fiddlemaker, although I have speedlights and have used them from time to time, artificial lighting is always a last resort. I always prefer available light. Essex County MA is where I spend a great amount of time birding. In December and January, I am at PRNWR several times a week. I also have many agent clients in Newburyport and do a significant amount of real estate photography in the area.

I want to thank everyone for the warm welcome!
Not sure how to navigate this site. Newest Pictures the place to post photos?
Sounds like a stupid question, right?

I'm brand new to UHH, but hardly new to photography. I've had a camera of some sort since college days. Admittedly, that was a long time ago... I bought my first really good 35mm camera 38 years ago when my son was born. My career was in construction administration and I would photograph all my projects. After my stepson earned his private pilots license, we would rent two seaters and fly the projects so I could take aerial photos. We've come a long ways since the days of film processing.
About 10 years ago, I decided to leave construction and go into real estate. Like nearly all realtors then, I took my own listing photos, but when I started getting getting pricier listings, I hired so called "professional" photographers. It didn't take long to realize that I didn't need them, so I bought a Canon 600D, an ultra wide angle lens and good tripod and shot a couple of my listings. Everyone in my office asked me who was taking my photos. When I told them I was taking them, I suddenly had requests to shoot listing photos from all my fellow REALTORS. That brokerage was part of a regional brand and soon I was working for not only my own branch, but numerous others in the state. Over the years, I have built a pretty solid little business. I shot 150 properties last year and I'm working alone.
My real passion is wildlife photography, so I describe myself as a wildlife photographer who moonlights as a real estate photographer. Accordingly, I have a camera in my hand every day.

I guess you could also say I'm a Canon guy and currently own 4 Canon cameras along with an assortment of lenses and other gear.
I'm happy to join you all here on UHH.