STOP!
Don't format NOW! That will cause you to "lose" the images now on the card.
If you are going to try to recover the missing images, do that before formatting the card.
Then make sure ALL images you want to keep have been safely copied off of the memory card.
Possibly what happened is your camera created a second folder on the memory card. There is a limit to how many images can be stored in a single folder, after which the camera automatically creates a new folder and starts putting the images in that.
Just to clarify about formatting...
- There are two types of format... "quick" and "deep". Normally all that's needed in-camera is a quick format. This simply sets all the old images on the card so that they will no longer be seen and marks then as "okay to overwrite". In this state, so long as you don't start overwriting and don't do another formatting, the images often can be recovered using special software. "Deep" formatting is rarely necessary and more completely "wipes" the memory card. It is usually done in an attempt to "repair" a card that's been acting up in some way. However, with the cost of most memory cards so low, it makes little sense to repair, usually is better to just toss an unreliable card and replace it with a new one (which should be quick formatted before 1st use).
- Quick formatting also should be done to a card that's been formatted in a computer or has been used in another camera. This is to ensure the file format and data structure on the card is fully compatible with the camera it's being used in.
- Get in the habit of formatting your memory card in the camera before you take the first shot on it. Do this with new memory cards as well as when reusing the cards. Just be sure when reusing the card that you have already copied off any images you want to keep.
- It is best to remove the memory card from your camera and put it into a card reader to download the images. This minimizes wear and tear on the camera, as well as making for the fastest and most reliable copying of the image data.
- Whatever method of download you use, be sure to "copy" the images onto your computer rather than "moving" them. This way the originals remain on the memory card until you are certain they have been safely copied onto your computer (and hopefully to some sort of data backup, as well). Only after this is done, put the card back in the camera and do a quick format on it.
- It is better to use multiple small memory cards than one big one. Don't "put all your eggs in one basket", in case that "basket" fails! If you have thousands of images on a card, stuff from weeks of shooting, and something happens to the card it can be a real disaster. Good quality cards rarely fail, but it does happen. More likely would be losing a card or accidentally sending it through the wash in a pocket or something dumb like that. But, whatever, it is better to have a handful of smaller cards that are switched out frequently, downloaded regularly, stored safely awaiting their next use, then formatted before fresh images are sent to them.
- Get a fine point Sharpee pen and write your name, phone and email on each of your cards. This way if you ever lose one, there's at least a chance that someone finds it and returns it to you. I started doing this after an incident on another forum... someone found a memory card full of hundreds of wedding photos. No info on the card. But the finder persisted, was able to identify the church in some of the photos, contacted them and found out who had gotten married on the date the photos were taken, then ultimately was able to get in touch with the pro photographer who had lost the card. She was VERY grateful to get it back!
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2), EOS M5, some other cameras, various lenses & accessories
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