[Not a Number]

So - your Mac is almost certainly doing something similar. I do not know if the creation of these files & folders can be prevented or not. IMHO, it's a PITA - created by people who think they know better about how MY data should be handled! Shame!!!

The Mac OS creates these files to store auxillary information and for caching purposes. All OSes/filing systems do this using various schemes. Some put this information in the file tables which means larger file tables more prone to corruption. There are pluses and minuses to either. WIndows creates thumbnail files for caching. You don't ordinarily see them since the get placed in a system folder on your Windows drive. The downside with this is since they don't get stored on removable drives they have to be built every time you connect the drive to a new Windows PC. Many Windows applications will create auxiliary such as the .xmp sidecar files used for PEF RAW files or .tmp or .idx files. Some of these you never see because the go into the temp directories or are deleted by the application.

You can delete these files but the Mac OS will just create them again the next time you attach the card slowing down read/write times and increasing the chance of corruption if you remove the card before all the cache writes are done.

If you set the write protect tab on the files won't get written to the card. But then you can't delete files off the card either.

If you know a better way build a better mouse trap write your own OS and filing system and the world will beat a path to your door.

[YeOldePentaxian]

A few comments, and a few questions.

Something strange is happening here, and there have been many useful comments in previous posts about the writing of hidden OS files etc.

Personally, I suspect a hardware issue not a software problem.

I have been using Pentax cameras with a multitude of different Mac models for over 10 years and I don't remember ever seeing this issue with various permutations of Optio WPi, K100, K200 - reading images with multiple internal slot and external USB readers or direct connected transfer by USB cable(s) / OS versions from 10.5 through 10.12 / SD cards from Kingston, Transcend, Samsung / card sizes ranging from 1 GB through 32 GB.

Just wondering,

1) What version of Mac OS X are you using?

2) What Mac model?

3) When removing the card from the camera to import photos, are you using an Internal SD card slot or an external USB reader?

4) Are you running a virus checker that might be doing an on demand scan when the card is mounted or the camera is connected?

5) Are you formatting the card in the camera, or formatting the card in your Mac?

If I was troubleshooting this problem on my own equipment I would do the following.

1) Format a different card (new or old, any size) using SD Formatter - SD Card Formatter - SD Association

2) Put the card in the camera and take a few shots

3) Connect the camera by USB cable to my Mac, try my usual download process

4) After transferring images, and assuming no issues during the transfer, eject the mounted camera and disconnect the USB cable

5) Turn the camera off and on to see if I get the formatting required message from the camera

6) If formatting is required by the camera, I would suspect there is an issue with the camera. If not, repeat the process by removing the card from the camera and downloading using your card reader to see what happens.

[35mmfilmfan]

Not a Mac user, but I had a similar problem - cured it by always setting write-protect on SD card before putting it into card reader. This made it impossible for the card to get corrupted.

HTH

Tony

[slip]

Did you try formatting the card in the camera instead of your mac? Did you try a different Sd card?

Randy

[lisabluesky]

Ok, I just went through the full card formatting provided through SD formatter SD Card formatter for Mac Download - SD Association
properly "ejected" the card (can I add a sarcastic tone of voice here for the people who suggested I wasn't already doing this?) from my Mac
Still showing "card is not formatted"...did a camera settings format, took a photo, inserted card into Mac, download photo, put it back in the camera and it works....except there are no photos. And I didn't erase them, and the "erase photos after downloading" option is not selected on my Mac. Interesting.....at this rate, I'm going to put this huge card in some other camera or device and get a small one to use in this camera.

[MarkJerling]

Lisa. I'd suggest you go back to the basics. Try a different card in the camera or format this card using the camera and use that. Then, try downloading the photos using a Windows laptop. Next try same in your mac. That way, you can establish if the problem is the mac or the camera. Good luck!

[Cthulhugan]

I have no problems with my Mac, card reader, and K-3. All my cameras are very tolerant of extra files, and I keep a README.txt file in the root directory with my name, address and phone number (in the hope I'll at least get the SD cards back if the K-3 is lost or stolen). I never delete images from the card on the Mac, I always re-insert the card in my camera and "delete all images". I format my cards infrequently, so I don't have to re-install the README, but when I do, I do it on the camera.

Try this to rule out something in your download/import procedure:
- insert a working, writable SD card in your Mac
- do NOT download pictures
- unmount/eject the card and remove it from the Mac
- insert in camera and try it out

If the card works in the camera, then the issue is being caused by your download and/or import procedure. If the card does NOT work, then something is messing with the card when mounted or ejected (e.g. anti-virus software, file system utility, etc.). There are enough anecdotal accounts of cards working after being mounted on a Mac that it seems unlikely the problem is with any of the software in a standard, as-shipped configuration, so I'd suspect a 3rd party app or utility of causing the conflict.

[TwoUptons]

If you are using Photos, and you're unmounting the card from Photos, I would also suggest you open a Finder window to make sure no other program is still using the card.

I've had similar behavior if I had anything else even looking at the card, though that hasn't happened in a while...

-Eric