dleebrick Loc: Indian Land, South Carolina

My 128GB San Disk Pro was finally about full of mostly RAW images, so I made sure that I had transferred everything I wanted and reformatted the card in my CANON 80D, using the standard formatting option. I then shot several hundred images in the 80D. It seemed to me that the write speed to the card had degraded somewhat. It occurred to me that maybe I should have done a Low Level format, which deletes all information and data on the card, vs just the normal formatting which simply resets the file system.
So to test this hypothesis, I formatted the card again in the 80D, selected high shutter rate and set the camera to Manual. Holding the shutter down, I got 25 exposures before the buffer filled and the write speed slowed to a crawl. Then, I reformatted the card using the low level formatting option, everything else being the same, and held the shutter down until writing slowed to a crawl. This time I got 32 exposures before the buffer filled and the write speed slowed to a crawl.
So, this little experiment tells me that if you want to get the most out of a top tier high write speed SD card, you should do low level formatting rather than the quick and dirty standard in-camera formatting.
Has anyone else seen this effect?

TriX Loc: Raleigh, NC

Were all the exposures in both tests of exactly the same image and were they raw or JPEG and did you conduct the test more than once? I have not tried this and see no reason why the write speed should be different, but I’m always ready to learn something new. First though, I want to make sure that all the variables have been eliminated except the format method.

LFingar Loc: Claverack, NY

That is covered in the Canon manual. Look in the section on formatting and you will see that it tells you to do an occasional Low Format to restore full write speed. BTW, it has nothing to do with data that is on the card or every camera would have the same issue, which they don't. It's about how Canon cameras write data to the card. They do it differently then other manufacturers.

TriX Loc: Raleigh, NC

Do you know the details of how they are different? Not doubting, just interested in understanding the mechanism since the file system is the same in both cases. My 5D4 manual says to low level format the card “if the writing speed seems slow”, but it doesn’t mention doing it periodically that I can see (page 73).

Scruples Loc: Brooklyn, New York

I have never seen this effect. For a simple reason. I don't format my memory cards when full. I had a bad experience years ago and that has jaded me. I had a 4GB Card and filled it completely. I tried to transfer the files. I though I did and then format the card to be used again. They were expensive back then. I didn't do a complete transfer and lost all of my photos.
From then on, I have never formatted a card and when filled, I transfer the photos to my external hard drive. Then I label the card and store it away for future review of the original.
As for a decay in write speed this is a defect that the manufacturer should be made aware of. The presence of a file should not interfere with another file being written unto it. There may be a damaged pin which becomes more noticeable with each format or the memory card may need to be defragmented. If you format your memory cards do it carefully and according to the camera manufacturer's directions and card manufacturer's instructions. Play it safe and don't format your memory cards at all.

johngault007 Loc: Florida Panhandle

It's trinary 1s , 0s, and Zs.

All kidding aside, I would be interested in data supporting this theory. I am always up for more learnin'

johngault007 Loc: Florida Panhandle

Srcupes, be careful with this. There are white papers out there showing the possibility of long-term storage degradation on flash media. If I can find the link I'll post it.

lamiaceae Loc: San Luis Obispo County, CA

I'm thinking that true. I only know of one type of FORMAT (command) on my digital Pentax, Fuji, Kodak, and Samsung Cameras.

Some of these differences might be why some people have trouble swapping SD or CF cards between cameras they own of the same brand. I never notice anything weird when I swap cards between three of my DSLR Pentax cameras.

LFingar Loc: Claverack, NY

As I am sure you know, the only data on any digital storage device, such as an SD card, is 1's and 0's. The file system used makes no difference. SD cards use FAT32 up to 128GB cards capacity. A typical format simply overwrites the data area being formatted with random 1's and 0's. Effectively destroying the data for all practical purposes even though there are recovery programs that can retrieve at least some of the data. Not your typical recovery programs though. Programs writing to the storage device do so by setting the Bits in the sectors to 1 or 0 as necessary to represent the new data. Write speed is un-affected by previous data or the random format. Canon, for some reason writes data using only 1's. (Maybe it's only 0's. I forget.). Let's say it is 1's. The Canon Low Format sets everything to 0. When a Canon camera is writing data it therefore only needs to insert the necessary 1's to write that data. Maybe they feel this is quicker, or was at one time anyway. The slowdown comes because when writing to a sector that has old data or a random format the camera first must format that sector as 0's. It does it extremely quickly but it is still enough to slow down write speed during high data transfers.
That's as it was explained to me by a Sandisk tech rep a few years ago. I only do Low Formats even though I rarely do burst shots of more then 4 or 5 and I never shoot video.

chase4 Loc: Punta Corona, California

Take a look at this, I see your camera has been tested. chase


https://www.cameramemoryspeed.com

TriX Loc: Raleigh, NC

Thanks very much for the explanation - interesting. I guess I’ll go low level format my cards and see if I can tell a difference, although like you I rarely shoot long bursts.

Edit: What I’m struggling with is how the file system knows if the sector/blocks are set to zeros unless it reads the sector first so it will know whether or not to format it - like a RMW (read modify write) cycle. The file system obviously knows what sectors are available to be written to, but not sure whether or not it keeps track of whether the sector is set to all 0s. Honestly, I don’t know enough about the specifics of FAT32 to know the answer, but if there’s a file system expert online, I would love to know. Seems kind of inefficient to to do either a RMW or an extra write cycle each time, but there’s probably something I don’t understand.

catchlight.. Loc: Wisconsin USA- Halden Norway

... Do not believe unsubstantiated claims... In camera is best for formatting, and Low Level is wrong.

Quote source: https://photographylife.com/how-to-properly-use-and-care-for-memory-cards

"You do not want your computer to do a low-level format of your memory cards. In fact, performing a low-level format, where the computer will go through each memory block on your card and fill it with zeros is bad for the overall health of your memory card, especially if you do it often, since those are write operations and each memory cell on your memory card only has so many writes to it before it becomes unusable. Plus, low-level formatting takes forever to complete, and if you ever want to retrieve files in case of accidental formatting, you will never be able to do so. When formatting memory cards in your camera or performing a Quick Format on your computer, the formatting process simply re-creates the index table that stores where files are physically located on the memory card, so existing files are simply written over when a write operation takes place. You don’t see those files on your camera or your computer, but they are still there. That’s why it is possible to restore images from a memory card, even if the card is formatted. It is important to note that memory cards under 32 GB are typically formatted with FAT32 file system as seen above, whereas cards with larger capacities will be formatted with exFAT file system, due to capacity and file size limitations. Keep this in mind when manually formatting cards on your computer."

... and also a full format with erase causes a lot of stress and heat and can shorten the lifespan of your SD if done often enough.

jerryc41 Loc: Catskill Mts of NY

That's interesting, especially for Canon owners. I've seen very few cameras that offer a low level format.

Collhar Loc: New York City.

"Play it safe and don't format your memory cards at all".
What???.....No

Longshadow Loc: Audubon, PA, United States