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SD card cannot be read in EOS Rebel T7

PhotoJenic
Apprentice

I have a Canon Rebel T7, a 256mb SD card (full size not micro,) and a Mac.

When I use an adapter and plug the card in it says, “this disk inserted was not readable by this computer.” If I reformat it on my Mac then my camera says that it can’t read the card and I have to format the card on my camera. If I format the card on my camera then my Mac gives the same not readable message. I’ve done so much googling I can’t find an answer!

I’ve tried two different brands of 256mb SD cards. The only card that works on both my camera and Mac is an old 4mb card I’ve had for years.

 

Is the card size too big? Do new SD cards require a different card reader? (My reader is years and years old. I had been using a Mark II for 14 years and it just died and I’m unable to afford to upgrade.)

It’s been a giant headache as I photograph a service every Sunday and I now have to transfer my photos onto my mom’s PC to a flash drive to get them onto my Mac to edit. She’s only visiting so once she leaves I can’t access my photos. Please help me before I pull my hair out!

20 REPLIES 20

shadowsports
Legend
Legend

Greetings,

For your T7, I would suggest a full size SD card UHS-I, 32GB or smaller. 

SanDisk, Lexar or similar.  Your cards should be purchased from a reputable source.  B&H photo, BestBuy, etc. 

Avoid Amazon, sellers there frequently and sometimes unknowingly sell counterfeit cards.  

This is a good card.  About $12 😀

shadowsports_0-1695711030196.png

~Rick
Bay Area - CA


~R5 C (1.0.6.1) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, +RF 1.4x TC, +Canon Control Ring, BG-R10

~DxO PhotoLab Elite ~DaVinci Resolve ~Windows11 Pro ~ImageClass MF644Cdw/MF656Cdw ~Pixel 8 ~CarePaks Are Worth It

The Canon page on the T7 says it supports SDXC: https://www.usa.canon.com/shop/p/eos-rebel-t7-ef-s-18-55mm-f-3-5-5-6-is-ii?color=Black&type=New

So 256GB should be OK... right?  Or am I looking at the wrong version of the camera?

Ian

The xxxxD models are listed to be compatible with SDXC cards, but they are not.  Speaking from personal experience and numerous posts like this one, they do not.

My T5 would lock up, give formatting errors, and other bad things.  If put the same cad into my 6D, no problem.  Put a SDHC card in the T5, no problem.  

Insert a different SDXC card into the T5 and cycle repeats. They don’t work.

--------------------------------------------------------
"The right mouse button is your friend."

Oh, interesting!  Then the 256GB card may be the problem.

But if true, then that's definitely a bug.  The T7 claims SDXC compatibility, and a camera that new should have it in any case.

I can't find anyone else having this problem with the T7.

This looks like a good guide to cards for the T7:

https://havecamerawilltravel.com/canon-eos-rebel-t7-sd-card/

He doesn't mention problems with SDXC; in fact, he says "I’ve used UHS-II SD cards in my Rebel T7, and they work just fine."  All the UHS-II cards I can find are SDXC.

These articles recommend a bunch of SDXC cards for the T7:

 

Here is an example of the identical issue from a year ago.

https://community.usa.canon.com/t5/EOS-DSLR-Mirrorless-Cameras/EOS-Rebel-T7-SD-Card-quot-Cannot-Be-A... 

The entry level Rebel bodes, xxxxD, do not like SDXC cards.  

The beginner level Rebel bodies, xxxD, do not seem to [have] the problem.

--------------------------------------------------------
"The right mouse button is your friend."

AtticusLake
Mentor
Mentor

@PhotoJenic wrote:

I have a Canon Rebel T7, a 256mb SD card (full size not micro,) and a Mac.

I think you mean a 256GB card.  "mb" is millibits -- a thousandth of a bit, which is impossible.  "MB" would be megabytes, but there are no 256MB cards on the market.  This may seem nit-picky, but the size of the card really matters, so it would help if you could confirm what you really have.

 


If I reformat it on my Mac then my camera says that it can’t read the card and I have to format the card on my camera. If I format the card on my camera then my Mac gives the same not readable message.

When you "format" a card, what you're actually doing is creating a new, blank, filesystem on the card.  So the question is, what kind of filesystem?  I don't use Macs myself, but I would guess that a Mac might create some kind of Apple filesystem.  If so, then it's no wonder your camera can't read it, because a camera won't support Apple filesystems.

If you format in the camera, then it will create an exFAT fileystem -- assuming that the card is actually 256GB.  It may well be that your Mac can't read this, if it's an old one.  Then again...

Do new SD cards require a different card reader?

I'm not sure about this; if your reader supports SDHC, then it might work for SDXC.  But from what I'm seeing online, formatting the card may be an issue.  To be safe, use a reader that specifically supports SDXC.

I’ve tried two different brands of 256mb SD cards. The only card that works on both my camera and Mac is an old 4mb card I’ve had for years.

I have to assume you mean 4GB (4 GigaBytes, not 4 millibits).  In which case, this is no surprise; the camera will format it as FAT, if it's that small, and then the Mac should have no trouble reading it.

Bottom line:

  • Understand your card capacities, and the notations used to specify them
  • Understand the generations of SD (SDSC, SDHC, and SDXC) and the sizes of cards they support
  • Understand the different types of filesystem

There's plenty of info about these online.  The "Comparison" section of the Wikipedia article has a helpful table: https://en.wikipedia.org/wiki/SD_card#Comparison

I made a video about memory cards that might help: https://moonblink.info/MudLake/tech#Cards

You might find the other videos on that page useful, too.

 

 

"I don't use Macs myself, but I would guess that a Mac might create some kind of Apple filesystem."

While the native Mac filesystem is HFS/APFS, they have the capability of formatting in FAT, which is what the camera requires.

If the card is SDXC -- i.e if it's bigger than 32GB -- then it needs exFAT, not FAT.  As I noted I'm not a Mac user, but I seem to recall they were late to the game with supporting exFAT.

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