Capacity of a Lexar Silver 256gb CFexpress B memory card in my D850

[Gonzalez49]

Following my recent successful updating of the firmware in my D850 I am now able to use CFexpress memory cards. (Thank you to the forum members who helped me with that!)
I currently have a Lexar Silver 256gb card in the camera, plus a 16gb SD card in the second slot. In the photo shooting menu I have selected Lossless compressed NEF (RAW) compression in the NEF(RAW) recording tab and NEF (RAW) +jpeg normal black star in the image quality tab. Primary slot selection is XQD card slot.
My understanding was that the capacity of the 256gb CFExpress memory card is very high, much higher than my previous 64gb XQD card. Thousands of images, indeed! But in the top screen of the camera there seems to be only a capacity of 744 images, which is only 100 more than the XQD card.
Am I misunderstanding something here, or are there other selections I need to make in camera's menu? Grateful for all explanations!

 

[Needa]

What is your secondary slot function set to? Overflow? Did you format the XQD card in camera before use?

 

[BF Hammer]

Maybe change the recording to Raw in primary slot, jpg in secondary.

If you set the secondary slot to backup the primary, your limit in capacity (and write speed) is that 16GB SD card. Since jpg files are much smaller in size than Raw, splitting the file types to write on the 2 different cards won't slow you down too much. Or consider buying a bigger and much faster SD card for doing the straight backup if you really want that.

 

[Clovishound]

I use the same setting BF suggested in my Z8. Raw files go to the CF express card, and I have a 256 GB SD card (relatively inexpensive) set to jpg. I can shoot for months without transferring or erasing the jpg files on the SD card. It's nice to have a RAW backup, but I can live with having a full sized JPG in the off chance that something happens to my RAW files.

Note: if you are shooting a lot of high speed strings and fill the buffer often, try turning off the backup to the SD card. I run into that from time to time when shooting birds in flight. Turning off the SD backup seems to help. I could do a test run and verify that, but haven't taken the time to do it. I've just relied on my impression while shooting.

 

[Gonzalez49]

Thanks for your replies!!
The secondary slot function is set to RAW primary - JPEG secondary. It looks like I should get a 256 GB SD card, as per Clovishound, and BF Hammer (?)

 

[Needa]

Seems reasonable to me, all my card pairs match size.

Add: but I use back up function for the second card.

 

[Clovishound]

Thanks for your replies!!
The secondary slot function is set to RAW primary - JPEG secondary. It looks like I should get a 256 GB SD card, as per Clovishound, and BF Hammer (?)

I believe that is how it's set up on my Z8, and should be the same for the D850. I would recommend clearing your cards and then shoot a few images and check each card and make sure all your NEF files go to the CF Express and all the JPGs go to the SD. You can use your current SD until you get a larger capacity. Your current 16 GB should hold around a thousand jpg images. A 256 should hold close to 20,000. SD cards are relatively cheap (although a quick online search shows they have increased in price a good bit since I last purchased one), so I would recommend getting one for convenience sake. Get whatever capacity your wallet is comfortable with. A 128 should hold enough images to back up several outings, depending on how much you shoot on an outing. A backup card or two is not a bad idea, although it's more critical for your primary card.

 

[BF Hammer]

A

I believe that is how it's set up on my Z8, and should be the same for the D850. I would recommend clearing your cards and then shoot a few images and check each card and make sure all your NEF files go to the CF Express and all the JPGs go to the SD. You can use your current SD until you get a larger capacity. Your current 16 GB should hold around a thousand jpg images. A 256 should hold close to 20,000. SD cards are relatively cheap (although a quick online search shows they have increased in price a good bit since I last purchased one), so I would recommend getting one for convenience sake. Get whatever capacity your wallet is comfortable with. A 128 should hold enough images to back up several outings, depending on how much you shoot on an outing. A backup card or two is not a bad idea, although it's more critical for your primary card.

All memory and hard disk storage are skyrocketing in price this year. AI datacenters have bought up all the product capacity of all the manufacturers for 2026 as early as April this year.