What SD data rate for photography?

[photo1x1.com]

Hi all,
I'm working on a video to explain SD cards. I think I know all the ins and outs, but what I don't know is what data rate/write speed can different cameras utilize when it comes to shooting stills?

Let's say I shoot continuously at 10fps with a Sony a7IV. The file size is roughly 50MB. That would be 500MB/s once the buffer is filled, which does happen faster than Sony actually says.
I also cannot find real info about buffer sizes.

So whether I use a V90 or a V60 card doesn't make all that much of a difference - I'd still have to wait what feels like forever unless I use a CFexpress card.

And another question please: there don't seem to be standards for sequential write speeds for CFexpress cards. Any idea why SD is over-standardized, while CFexpress doesn't have a standard at all?
Any input is greatly appreciated. I have spent hours searching for some of the information.

 

[AlanKlein]

Camera manufacturers specify the speed of the memory cards needed for their cameras. Trying to guess based on other factors seems fraught with danger. I would tell viewers to check the manuals for their cameras for that information.

 

[photo1x1.com]

Thank you, Alan. But they would only list the generation of cards. E.g. SDXC. But they don't list the maximum speed the camera would be able to make use of.
Some have slightly more detailed video specs if a camera supports different video codecs, but that still isn't all that informative.
I found this site, which is super awesome, but it hasn't tested new cameras in the last four years and many older ones are also not tested. One moment, please...

 

[RacePhoto]

I don't know if this is what would be any help, but the makers list minimum speeds and I'll assume anything over that, doesn't make the camera work better or faster.

I know I've had SD cards and the camera would just shut off when the transfer rate isn't fast enough.

Kind of like, if it works, it does and if it's too slow, it doesn't. I can't imagine that there's anything better than, it's recording images? Sometimes I think the same for buffer and transfer with CF cards. It seems that the slowest link in that, when I'm doing long night exposures, isn't the card, but instead the camera processor.

Just some thoughts, I'm not sure if there's something I missed in that. Weakest link = best speed limit.

 

[AlanKlein]

Thank you, Alan. But they would only list the generation of cards. E.g. SDXC. But they don't list the maximum speed the camera would be able to make use of.
Some have slightly more detailed video specs if a camera supports different video codecs, but that still isn't all that informative.
I found this site, which is super awesome, but it hasn't tested new cameras in the last four years and many older ones are also not tested. One moment, please...

This is what Sony says about my RX100iv camera. Note they list the speed requird in the video section which really needs the faster speed. Of course, other cameras with high still rates might use i faster in still mode. Check the full specs for speed required.

From Sony manual:
You can use the following types of memory cards with this camera.
For movies, refer to “Memory cards that can be used for movie recording” on this page.
Usable Memory Stick media
Memory Stick PRO Duo / Memory Stick PRO Duo (Mark2)
Memory Stick PRO-HG Duo
Memory Stick Micro (M2) (Mark2)
*Memory Stick media with a capacity of up to 32 GB have been tested and proven to operate
with this camera.
Usable SD cards
SD memory card / SDHC memory card
SDXC memory card
microSD memory card / microSDHC memory card
microSDXC memory card
*SD cards with a capacity of up to 128 GB have been tested and proven to operate with this
camera.
Memory cards that can be used for movie recording
When shooting movies in XAVC S format
SDXC memory card or microSDXC memory card with a capacity of 64 GB or more (SD
Speed Class 10, or UHS Speed Class U1 or faster)
When recording in 100 Mbps or more, an UHS-I-compatible SDXC memory card or
microSDXC memory card with a capacity of 64 GB or more (UHS Speed Class U3) is
required.
When shooting movies in AVCHD or MP4 format
Memory Stick PRO Duo (Mark2)
Memory Stick PRO-HG Duo
Memory Stick Micro (M2) (Mark2)
SD memory card / microSD memory card (SD Speed Class 4 or faster, or UHS Speed
Class U1 or faster)
SDHC memory card / microSDHC memory card (SD Speed Class 4 or faster, or UHS
Speed Class U1 or faster)
SDXC memory card / microSDXC memory card (SD Speed Class 4 or faster, or UHS
Speed Class U1 or faster)
Note
Not all memory cards are guaranteed to operate correctly.
When you use a memory card with the camera for the first time, it is recommended that
you format the card on the camera before use for more stable performance of the memory
card.
Note that formatting erases all data on the memory card permanently, and is irreversible.
Save valuable data on a computer, etc.
Images recorded on an SDXC memory card cannot be imported to or played on
computers or AV devices that are not compatible with exFAT when connected using a
micro USB cable. Make sure that the device is compatible with exFAT before connecting
it to the camera. If you connect your camera to an incompatible device, you may be
prompted to format the card. Never format the card in response to this prompt, as doing
so will erase all data on the card. (exFAT is the file system used on SDXC memory
cards.)
[

 

[photo1x1.com]

Thanks you two. I checked all those specs for my cameras too. But it's somehow not really satisfying for a nerd like me who always questions things. I think the minimum speed is mainly for video, but for photography, once the buffer is full, it would even benefit from a much faster write speed than video requires. So I wonder if the video minimum write speed is also the maximum speed the camera can write.

 

[AlanKlein]

Thanks you two. I checked all those specs for my cameras too. But it's somehow not really satisfying for a nerd like me who always questions things. I think the minimum speed is mainly for video, but for photography, once the buffer is full, it would even benefit from a much faster write speed than video requires. So I wonder if the video minimum write speed is also the maximum speed the camera can write.

It's seems logical that the camera company would list the minimum speed required for the camera regardless of where it;s required more - video or stills. Otherwise, all the buyers would complain about their manuals.

 

[photo1x1.com]

True, but I would expect the specs to also show the maximum write speed of the camera, so that people know which card speed makes sense and which one doesn't (depending on what they are shooting).

 

[RAZKY]

Hi all,
I'm working on a video to explain SD cards. I think I know all the ins and outs, but what I don't know is what data rate/write speed can different cameras utilize when it comes to shooting stills?

Let's say I shoot continuously at 10fps with a Sony a7IV. The file size is roughly 50MB. That would be 500MB/s once the buffer is filled, which does happen faster than Sony actually says.
I also cannot find real info about buffer sizes.

So whether I use a V90 or a V60 card doesn't make all that much of a difference - I'd still have to wait what feels like forever unless I use a CFexpress card.

And another question please: there don't seem to be standards for sequential write speeds for CFexpress cards. Any idea why SD is over-standardized, while CFexpress doesn't have a standard at all?
Any input is greatly appreciated. I have spent hours searching for some of the information.

I would check out You Tube videos - some of those folks know about SD cards.

 

[photo1x1.com]

I would check out You Tube videos - some of those folks know about SD cards.

Thanks, Razky. I did. But it seems there is just so much you can find out without the manufacturers of the cameras telling you their real specs. I can do experiments with my own cameras and cards, but I can't do it for others like in the link I posted above where someone tested dozens of cameras with very surprising results. Unfortunately these results are rather old.

 

[RAZKY]

Thanks, Razky. I did. But it seems there is just so much you can find out without the manufacturers of the cameras telling you their real specs. I can do experiments with my own cameras and cards, but I can't do it for others like in the link I posted above where someone tested dozens of cameras with very surprising results. Unfortunately these results are rather old.

While still widely used, SD cards are old technology - you may very well be on a mission to nowhere. Best of luck, nonetheless.

 

[photo1x1.com]

Thanks. You wouldn't believe how many questions I still get in this regard. And I'd assume it will stay like this for a while until the other cards get more affordable - or probably the cameras will get internal storage that is then transferred wirelessly .

 

[AlanKlein]

True, but I would expect the specs to also show the maximum write speed of the camera, so that people know which card speed makes sense and which one doesn't (depending on what they are shooting).

Who cares? You use card that has a speed to cover the fastest requirement the camera imposes regardless of the mode you're shooting in. Who's going to change the card to a slower speed because they're shooting in a slower mode. Just use the same faster card. You're complicating this and will just create problems for the camera users.

 

[photo1x1.com]

That's one of the problems I often see in photography. Just because things aren't well explained, doesn't mean they don't matter.
A v90 card costs 3x as much as the same v60 card. If you need let's say 5 cards, that can easily set you back 650 USD. I think people would care if they knew.

 

[AlanKlein]

That's one of the problems I often see in photography. Just because things aren't well explained, doesn't mean they don't matter.
A v90 card costs 3x as much as the same v60 card. If you need let's say 5 cards, that can easily set you back 650 USD. I think people would care if they knew.

Cost is a valid concern. But if the camera manufacturer isn't giving it, I wouldn't assume my calculations are going to be accurate. I'd stick with providing the rate the manufacturer recommends even if the user isn't using his camera for video. Maybe there's a outfit that provides info like this. DXO? Good luck.