Never Shoot Without Dual Card Slots

Never Shoot Without Dual Card Slots

In the past few weeks, Nikon and Canon have released their new mirrorless offerings, the Z7 and R, to much fanfare. Despite the great specs and form factor, I won't buy either for one simple reason: neither one has dual card slots. I never shoot anything without dual card slots, and neither should you.

When shooting for clients, shooting for myself, or just casually taking a few pictures of my kids, I always shoot with two camera card slots. I am fanatic about not losing any files, be it for clients or just myself. If it is worth shooting, it is worth protecting those files.

In the time between starting this article and finishing it, I had two photoshoots. In the second one, a compact flash card actually corrupted and was not recoverable. I tried several different software solutions, but all of them failed to recover the images on the card. 

Screenshot of Image Rescue Software for memory card recovery

Image Rescue was unable to recover my corrupted memory card


Even though that card corrupted during the shoot, I didn't lose a single file because I shot everything to two memory cards. I wouldn't have even tried to recover the files if I was not in the middle of writing this article because every image was safely on my other card. 

My clients pay me to deliver, and I sure couldn't ask them to redo a wedding because the kiss didn't save to my memory card correctly. 

Constant improvement by card manufacturers have led to fewer card failures, but they still happen. I'm not exactly smart enough to explain how flash cards work or what makes them fail, but I do know someone who is smart enough to understand them. Jeff Wischkaemper is a research professor in the Department of Electrical and Computer Engineering at Texas A&M University. Dr. Wischkaemper also happens to be a talented amateur photographer, so he understands the importance of memory cards to photographers.

"We used CF cards in an industrial product for over a decade. This was not a photographic application, but the primary function of the of the cards was to store files of similar size and composition to images. The CF cards were, without question, the weakest part of the system. Virtually all cards experienced some data corruption after years of use - many of them experienced complete corruption of the entire card, to the extent that no data could be read or written," Dr. Wischkaemper said.

I am all about minimizing risk and there are several ways you can do that. You can minimize risk by buying good memory cards from authorized retailers. I have less failures in my Lexars and Sandisks bought from an authorized retailer such as B&H than I have had with other brands bought in other places. I don't even want to know how many counterfeit memory cards I have used over the years because I didn't buy exclusively from authorized retailers. 

Another way you can minimize risk is changing out memory cards before they fail. As Dr. Wischkaemper said, eventually they all cards he used suffered some corruption or data loss. Replace the cards before they corrupt. Sell them or keep them as emergency backup. You can also do what I do and have a bowl of old cards on a shelf for no particular reason other than I might one day use that 1GIG 80x card from 2005.

In addition to both those ways, you should always shoot dual card slots. I only use new cards purchased from authorized retailers and I change them out regularly. But cards can still corrupt at any given moment, so every time I take a picture, it is written to card slot A and card slot B.

I choose to use raw to card A and JPEG card slot B for a couple reasons, but the main reason is when I shot Canon, I noticed that sometimes the raw file would corrupt when I was hitting the buffer, which was often on the horrible buffer and slow write speeds of the 5D Mark III. But while the raw file would be corrupted, the JPEG file on the other card slot would be unaffected and could be edited normally.

More likely than a card corruption problem, though, is human error. I've heard countless stories of camera bags being stolen, memory cards falling out of pockets, or photographers thinking they backed up the card, then shooting over it without getting all the files.

A lot of photographers suggest using smaller cards and changing them out more frequently. Delkin recently announced three new XQD cards and the smallest size was 64GB. At the time of writing this, B&H didn't offer any XQD memory cards smaller than the Sony 32GB. XQD is the only card format in the new Nikon Z7.

I actually think shooting with smaller cards and switching them out will make you more prone to lose images, because I think the more likely event is human error than card corruption. 

Large cards are all I use — large enough where I do not need to switch out cards during a shoot. I know cards aren't going to fall out of my camera and because I use two cards, I know that me losing my cards is much more likely than both cards being corrupted and unable to recover any files. My cards are only formatted at home, placed in my camera, and only come out when it is time to ingest. Never will I format a card during a shoot.

When you have formatted cards for years, it becomes a habit you can do without thinking and so if you never format during a shoot, you will never format the wrong card out of habit. After a shoot, my used primary cards go into a Think Tank Pixel Pocket Rocket and that stays tethered to me. My secondary cards stay in the cameras. If someone steals all my gear after a shoot, I still have the primary images.

I am really excited to see what my friends, colleagues, and sworn enemies do with these new Nikon and Canon mirrorless cameras. With the great EVF and cool new features, I think we are going to see a lot of great stuff that had not been done with DSLRs. But you won't see it from me. I won't take the risk. I may fall behind the times on this new technology but the risk of losing irreplaceable images for a client is going to be substantially lower.

For years, photographers shot single images on single frames of film. If you ruined the film by not properly rewinding it or in the development process, it was gone and there was nothing you could do. Luckily, times have changed and technology has advanced.

I'll bet you Robert Capa wishes he had a second copy of all the images he shot as he landed with Company E on Omaha Beach for the first wave of attacks on D-Day. Of 106 frames Capa took on D-Day, only 8 were salvaged after the darkroom assistant turned on too much heat while drying the film.

If I lost 94% of my clients files from a wedding or portrait shoot, I doubt they would be comforted much to know that Robert Capa's film was melted almost 75 years ago so no big deal. It happens, right? It doesn't have to happen. We have the technology to do better and our clients deserve better than for us to risk their files with one card slot when there is an option for two.

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172 Comments

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Nicolas KIEFFER's picture

Wow ! Seriously ?

Nick Viton's picture

Again, there are other advantages to using 2 card slots than just mitigating against card failure.

David Stephen Kalonick's picture

These comments are making me want to take crazy pills. If you have two card slots and you shoot weddings, why the fuck wouldn't you take advantage of such a simple backup? I'm considering showing this thread to couples in my consultations. It would be entertaining as hell to watch a photographer explain that they don't use two cards to a couple. Hey, I know you're forking over thousands for me to shoot your wedding, quick heads up, I'm stubborn as hell and have the option to shoot on two cards but have a strick one card policy because I've never had a card fail on me or lost a card. Don't worry; I got this. ​

John Dawson's picture

Like my mom used to say, wear two condoms. :-P

Lee Stirling's picture

I suppose no professionals ever made their living by shooting a D700.

Jan Kruize's picture

Pfffff here we go again...... but your absolutely right.... damned sony wheres that camera with four cardslots in it?

Timothy Turner's picture

I am using a Pentax K10D, ok it's old technology but it works very well, I have been using the same memory card for two years with no problem, I shoot upload, format, and start over. I also use a Mamiya 645 super for black a d white which I also enjoy very much, my point is all this old stuff works very well

Stachu Nowak's picture

Oh, so that's what I was doing wrong for last 20 years...

Card Life comes partly down to cell wear and the technology in use.. Newer cards with newer tech have a much greater cell life. Card have controllers in them and software that manage cell wear using Wear levelling. They often have over provision in them allowing duff cells to be swapped before corruption. Under used card will give the greatest reliability and wear re mapping is likely to happen when the card is formatted. I use 128gb cards and shoot up to 30gb per day so around 25%. its a shame card manufactures don't give cell wear ratings like ssd hard drives. Most memory cards are based on hard drive technology, CF is IDE, CFast is SATA, XQD is PCI express, CFexpress is NVMe over PCI express... all of which have S.M.A.R.T. implementations. SD cards are not based on hard drive tech other than SD Express bus which is new. I don't trust SD cards and reading around they don't seem to have much fault reporting or much implementation of S.M.A.R.T. You can have a look at the life of your card using something like https://www.hdsentinel.com/how_to_monitor_sd_card_health_status.php :-) for PC users

Franklin White's picture

I guess having been a film shooter I never really worried about the number of card slots.

Chris Rogers's picture

Oh boy....

user-184570's picture

This website and the people who work/write for it have lost their goddamn minds. You guys aren’t professionals, you’re insane. Get a grip and write some articles about photography, not about friggen card slots. Everyone who contributes to this site should be ashamed. Especially Patrick and Lee who are spreading an awful type of attitude into the photography world.

These types of articles don’t foster discussion. They foster hate and arguments. I’m disgusted I’ve ever even visited this website. Please take a long hard look in the mirror and figure out why you got into photography because I’m sure as hell this isn’t it.

http://www.nearbycafe.com/artandphoto/photocritic/2014/06/12/alternate-h...
Just another perspective on the Capa legend. Not so much an opinion on two slots.

amanda daniels's picture

I never understand why this is even a debate. You have an obligation to your clients to do everything in your power to ensure they get their images. Why would you choose to only shoot with one card if you have the option of 2? My main body I use a SD card and a CF card and the images write to both. My back up body is the one that only has 1 card slot, but I am sure to shoot all the important things on my main body. When I started weddings that is when I immediately went out and got a camera body with 2 card slots. I wasn't going to shoot a wedding without it. Is it a requirement? No, but I still don't understand why people would even want to risk it. I never want to have a conversation with my clients that I lost their images.

Personally I only buy bodies that have dual slots... I've lost work due to corrupted new card. Some people are more careful and have never experienced such, I pray you never do. I don't want to get that 'cold' feeling ever again if I can help it.

Nathan Thach's picture

Everyone laughs until it happens to you =X

miha zero's picture

Please dont educate me. Seldom has articles like this made impact on me more then any tabloid sensationalism, if ever.

Hence, please stop.

cameramanDop Shanghai Hong Kong's picture

So, what aout shooting with the new Zeiss ZX1?
It have internal memory only (no Card?)

Cosimo Vitali's picture

This article implies that if you can't afford a dual card camera, you shouldn't work. I disagree.
Don't get me wrong: if i could, i'd just go on with dual slot, and you are totally right, but I can't, so...

Andress Kools's picture

I never shoot on dual cards. I shoot on a small card and back it up after a session. Then I shoot on another card, etcetera. At the end of the wedding, I'll have all the RAW-files in at least three locations: the cards, my backup and my encrypted cloud storage. There's really no need for two card slots in a camera, unless you're really careless with your cards to begin with.

What a load of horse manure.
As for Capa - the darkroom disaster never happened. Do some searching and find out reality rather than the myth - since Capa quickly left the beach with only a few frames exposed.

Jacques Cornell's picture

This topic has been beaten to death. Nothing new here. As for Compact Flash cards, stop using them. The card readers are highly susceptible to bent pins, and this can fry a card.
Over the past 16 years I've shot single- and dual-card cameras, Compact Flash and SD, and I've never lost an image to a corrupted card. Ever. In my view, shooting with multiple bodies is better insurance against camera/card failure. After all, two cards full of corrupted files from a failing body is little solace.

Jacques Cornell's picture

The problem is that not all cameras have two slots, many one-slot cameras are otherwise very compelling, and many two-slot cameras are otherwise very unappealing to me. I shoot with three one-slot Panasonics because I really don't want three G9s.

Fascinating series of article on this site suggesting Robert Capra didn't lose any images from D-Day and instead bailed on shooting the event because it was so scary. http://www.nearbycafe.com/artandphoto/photocritic/2014/06/23/alternate-h... (And to me that says a lot about the horrors of war.)

Jacques Cornell's picture

Put an "I" at the front of the title and you're golden. Tell me what to do, and you're, well, let's just say not golden.

"I shoot to two cards so in case one becomes corrupted, the other is ok"....."I shoot JPG to one and RAW to the other" . kinda defeats the point doesn't it? I suppose YEA you get the JPG vs nothing, but I would never want to edit a JPG...ever. Just shoot RAW+JPG to both cards if you really want the JPG, and learn to control your shooting speed, get faster cards, or buy a camera with a bigger buffer.

Thomas Campbell's picture

JPGs edit a lot better than they used to. There will be some things you can't do, especially with color balance, but for the most part, if you get it right in camera, you will likely be completely fine editing from JPGs. It wouldn't be my first choice, but it is better than losing images.

another sony or fuji hardcore fan boy....

another sony or fuji hardcore fan boy....

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