A couple of months ago, I decided to insert a 128GB Lexar Professional 1000x CF card in the second slot of my Canon 1DX and leave it there. Why would I leave the card in the slot for the last couple of months? Because I wanted to see what it was like shooting to two memory cards at the same time and have every image that I shot be backed up in camera. I was also curious to see how many events I could shoot before filling the card.
As it turned out, so far I have shot 2 Bar Mitzvahs and receptions, 5 family portrait sessions, and our vacation in Mammoth. For those of you who follow my blog regularly, you know that I shoot everything in RAW, which makes for some really big files. Each image averages to about 24MB in size. I just checked the card and so far I have used up 100GB of the 128GB with a total of 5256 RAW and MRAW images. (I usually shoot receptions and parties in MRAW mode, which on the Canon 1DX is a medium sized RAW file, since the files don't need to be as large and rarely need extensive cropping.)
Since both cards in my 1DX were 1000x speed, it did not appear to slow down the 1DX at all, writing to both card slots as opposed to just one.
What I love about this high capacity card, is that it is essentially like having a Solid State Drive (SSD) in my camera, giving me that extra piece of mind as I shoot. God forbid I drop a card and lose it, or something goes wrong with one card, I have another to fall back on. With that said, I am happy to say that I have never lost an image from any of my memory cards or lost one during a shoot. Phew!
I am going out shooting in San Francisco today (for fun) and plan on keeping that same card in the second slot. The fun continues!