Micro SD / SDHC ???

Starting to get a little confused now...
I'm trying to find a cheap SD card for the 5D MkIII to act as dual card writing, probably around 32GB.
However I don't understand if there are any differences (mainly speed) between using a class 10 micro SD card with full size adaptor or just using a standard size class 10 card?

Any advice appreciated.

Okay, this may be long, but I'll be interested in the responses. When I got my 7d2, I used a very fast Samsung microSD 64gb card in an adapter with no problem. I later added a good CF card for rollover if I filled the SD. I never had an issue and had good write performance. Fast forward to a trip in June. I wasn't going to have a laptop along so I changed my on camera tactics. I bought 2 Lexar microSD 633x 32gb cards and one Lexar Pro CF card, also 32gb. That gave me two microSD/CF card pairs for writing to at the same time. When I got home from the trip, I found that both microSD cards has some partially corrupt images on them. The CF cards were fine. I'd be very surprised if I got two bad cards from Lexar. I experimented with only using the microSD and on CF to see if the redundant writes were the issue. Nope, still had about 1 out of a hundred partially corrupt images on both. Two different brands of SD adapters were used. Now I'm going to try another, newer adapter and see if that is the issue.

So, my original thinking was that using an adapter was going to be a good idea since on a SD card, it is the little plastic fingers on the back that get damaged for me usually. So this way that would be on the disposable part. Now I'm re-thinking that idea.

So, like you, I'd like to hear others issues or thoughts on microSD with adapter or full sized SD cards.

Well, I wouldn't go the MicroSD + adapter route. First off, the MicroSD cards are too dang small and easy to lose. Second, unless you have multiple MicroSD->SD adapters (granted, many MicroSD cards include the adapter), you'll need to be removing both the adapter from the camera and the card from the adapter whenever you need to change cards. Third, every friction/pressure contact presents a potential weak point and with MicroSD in an adapter, you've just doubled the number of possible failure points.

Besides the general wear and tear on removing cards and their contacts as mentioned by Jon, there really is no difference besides speed on a MicroSD and a regular SD card. If you ever crack open a new SD card, you'll find a very small (MicroSD-sized) electronic bit and a bunch of large contact points. All they did in MicroSD was downsize and re-orient the contacts. In fact, if you crack open the adapter, it is just fingerling connectors going to larger contact points.

csn_trojan wrote in post #17666021
Starting to get a little confused now...
I'm trying to find a cheap SD card for the 5D MkIII to act as dual card writing, probably around 32GB.

I can't tell where you live but Best Buy is a reliable source for memory. There is a sale virtually every week, usually Sandisk, that brings a decent card to about $1/GB. Right now for instance they have a 64 GB Pixtor (essentially Sandisk) SDXC for $55 (normally $150). Note you should check compatibility of all hardware involved before jumping into SDXC.

Put one of the Lexar micro SD cards into a different brand adapter. Shot a couple hundred shots over the weekend and no corrupted images. I'm not going to declare that the solution yet, but looks promising.