Canon Community Canon Community

Reputable Contributor
Posts: 954
Registered: ‎01-25-2018

Re: Formatting Memory Cards

For your wedding shooting with redundant recording to two cards I wouldn't bother with a backup to a portable drive at the event.  The odds of both cards failing (or you losing both cards) is very small and you would have to weigh that against the possibility of making mistakes while trying to hurriedly make a backup during a short down time OR getting distracted and having the portable drive and cards walk away while you aren't paying attention during a transfer.  I read on another forum about a photographer who was hurriedly transferring photos from his camera to a server and without thinking he chose his last used menu item on his second camera and instead of switching to communications he formatted the card instead.  Bad things happen when you try to do something important during a short down time during a long event.


There are no guarantees but coming out of years of risk management consulting I would secure both cards when they come out of the camera and not do anything else with them until you are safely back at your own office.


Changing cards often and having a second camera in use is good insurance against unusual system glitches.  A colleague who ran a product failure analysis firm told me several years ago about an event photographer who lost most of his material due to a camera failure that trashed both cards simultaneously and very little data was recoverable.  Dual cards are good protection against the more common card failure but when things really go wrong, splitting the event between several groups of cards reduces the potential for large loss.  You can drive the probability of image loss down to a very low level but you quickly reach the point where the cost of further decreasing risk increases at an extremely high rate and it isn't necessary (and certainly not practical) to drive risk to extremely low levels.


If you are doing a multi-day event away from your own turf, treat it differently and backup the files to another source and preferably a cloud at the end of each day.  A good friend lost days worth of images, both the cards and the backup drive, from his hotel room near the end of a long trip.



EOS 1DX M3, 1DX M2, 1DX, 5DS R, 1D M2, EOS 650 (film), many lenses, XF400 video
Frequent Contributor
Posts: 87
Registered: ‎03-12-2019

Re: Formatting Memory Cards

1. I spoke at some length with a number of engineers at several companies that manufacture memory cards utilized by Canon cameras I own, and deciphering the technical jargon, they agreed on one fact: while erasing photos you don’t want in the field is perfectly fine, erasing photos as opposed to formatting the card is a really bad idea.


They were unanimous in their recommendation: in their experience, most cards that have been sent to the manufacturer for data rescue have been repetitively erased and obviously not formatted following use.  Cumulative errors are apparently introduced in the memory cards over time while only erasing photos; these errors are not generally found with memory cards routinely formatted, especially if deep formatting is an option, in cards sent back to the manufacturer for data retrieval.


One caveat: while I’m not new to photography, I only have 4 years experience using Canon DSLR cameras. There is an entire world of DSLR photography out there I haven’t learned about, and while I consider myself a novice, I did take the time to talk with several companies after a brand-new memory card died on its second day of use. Ugh.


Chris P. Bacon

EOS 6D Mk II, 7D; 7D Mk II

Chris P. Bacon
F-1; AE-1; EOS 1V, 5D Mk IV, 6D, 6D Mk II, 7D, and 7D Mk II
Honored Contributor
Posts: 5,421
Registered: ‎06-25-2014

Re: Formatting Memory Cards

@Joel4JC wrote:
"2. Technically False, though true in practice. Why move a freshly formatted card to a new camera?"

In my case, I use two 5D Mark III to cover an event and all my cards are preformatted and could end up in either camera, unless I keep them separate and labeled, which I don't! So I am glad your answer is "Technically False". Thanks!

I think the reason this notion got started is that file systems have changed a bit over time (e.g., to accommodate higher capacity cards). If you were to format a card on a newer camera, then try to use it in an older camera, you run the risk that it may not work. But if you're swapping cards between two identical cameras at the same firmware rev level, I can't imagine that you'd have a problem.

Philadelphia, Pennsylvania USA
powered by Lithium

LIKE US on Facebook FOLLOW US on Twitter WATCH US on YouTube CONNECT WITH US on Linkedin WATCH US on Vimeo FOLLOW US on Instagram SHOP CANON at the Canon Online Store
© Canon U.S.A., Inc.   |    Terms of Use   |    Privacy Statement