Jack 13088 Loc: Central NY

That is a good question. Answering it is surprisingly difficult. Every digital camera I have owned shows the approximate number of photos left on the LCD display on top. But both of them are Nikon and I learned the hard way all manufactures have different display designs. (Before LR I had built my own database for cataloging photos and renamed the files with the camera type, serial number, and shutter count from the EXIF data concatenated as a unique key. Then I found my friends Canon does not have shutter count in the EXIF.) But if your camera does than stop when you have a couple of hundred shots left.

In the first place the 64G does not mean you have 64GB available for your use. The file access table takes a modest amount of space but SD cards also contain DRM data designed to render the card useless should you tinker with it in attempt to copy the whatever you think you bought. That seems ti takr quite a large amount of space.

Second all files are not the same size do to compression. Even RAW files are lossless compressed and vary in size. So even if you know the available memory you have to do some division by say the max size. Windows Explorer tells you the space used and available. So Apple Finder must also. So you can see it there.

burkphoto Loc: High Point, NC

Great point... And your illustration reminded me of one more reason to format cards only in the cameras they will be used in:

Different cameras have different card requirements. They will format cards differently, too. For instance, my Lumix uses ExFAT for large capacity cards. Many older cameras expect FAT 16 or FAT 32 format, so they can't read newer cards at all, because high capacity cards require ExFAT.

If I put one of my 64GB cards in my wife's old Canon G7, it doesn't even recognize it. And her little 512MB SD cards aren't worth the bother to try in my camera. They would be about like 24 (raw) exposure rolls of film... annoying!

buckscop Loc: Bucks County PA

Why reformat after each download?

zug55 Loc: Naivasha, Kenya, and Austin, Texas

If you delete photos you essentially remove the directory. You still have bits of images stored on your card that are gradually overwritten as you take new images. Formatting does a better job of actually wiping your card clean.

tomcat

After you download your images to your computer, put the card back into the camera and delete the files with the camera. I've been doing this for the past 10 years, all the time and then about once a month, I reformat the card too.

fotoman150

The general rule is not to let the computer delete or reformat your card. I only reformat in the camera that I’m using.

aellman Loc: Boston MA

And after 4 years, it may be time to retire the card itself. >Alan

Jack 13088 Loc: Central NY

Formatting also just clears the directory and leaves the data until they are overwritten. It is the equivalent of a fast format in most computer OS. I understand Canon provides a format that clears the data so it cannot be recovered presumably for security purposes. Deletion of the files one by one does not necessarily repair a corrupted file access table and is also tedious.

dyximan

I have a Mac and once I upload from my photos from my SD card, if I forget to reformat it and shoot more photos when I put the SD card back in. It will tell me what I have already uploaded and what the new photos are, and will ask if I want to upload the new photos only.

rook2c4 Loc: Philadelphia, PA USA

My experience says: No.

Back when memory cards were fairly small capacity and also were rather expensive, it made sense to format them regularly to free up space. Now, not so much. I haven't formatted my card in nearly two years. Works fine, no issues.

no12mo

Not sure I agree with your supposition. Find a way to get that card hooked up to your computer directly with a USB adapter. I'm not a reformat after use person. I've been shooting for decades right after the digital camera came out and never had to.

Just get that card hooked up as I suggested and not only will the transfer be faster, more reliable. You will be able to look at the free space as I illustrated in a previous post.

Good luck, yours truly

no12mo

Jack: See my previous post with illustration. The trick is to get that card out of the camera and hooked up to a USB adapter and hooked to your computer. Then offloads should be faster and you can actually get an idea of how much free space you have on the card

Others have said that the card should formatted *in the camera* which I agree with. But in another post I have stated that I have never had to reformat a card and I've been shooting digital since the beginning of the digital format. Sure go ahead and reformat a card if it makes you feel better and by all means do it in the camera.

If you want to be sure your data is removed, do it with my suggested approach and then get a utility that *wipes free space* using a DOD approved method that actually writes 1s and 0s that will take out the data that is actually still on the card ... Otherwise, the images can be easily retrieved by someone who may have nefarious motivations.

Good luck and have fun, Al

burkphoto Loc: High Point, NC

The main reason to format a card after copying images to your computer is organizational — it makes it easy to keep separate events or subject matter in separate folders.

Formatting at low level is seldom worth time unless you have sensitive subject matter on a card you wish to remove.

If you do that low-level formatting in a computer, then you should re-format the card in the camera right away. This ensures that any model-specific hidden or visible files required by the camera get written there, to prepare it for use.

I have yet to buy an SDXC card that worked in my GH4 before I formatted it in the camera.