D800 Buffer only holds tiny amount of images: What's wrong?

FlowtographyBerlin

Inspired by the Sports Jounalism thread I was reminded of an issue that I've been facing in various situations lately, the last was even in a normal studio shooting: When I shoot many frames in a row, I often end up with the camera being busy writing to the card and the shutter button being blocked, which is *very* humiliating and frustrating.

Yes, I "only" have 30MB/s cards (San Disk Extreme III CF and San Disk Ultra Class 10 SDHC), but I just looked it up in my camera manual, and it says the buffer can hold 17 RAW images (14 bit lossless compression full frame, which I use when I use RAW), and up to 100 JPEG in the setting I use when I use JPEG. This is more than should I ever touch, and yet I've had the above problems.

I for the first time checked the value on the display that tells you how big the remaining space is of the buffer (how many images), and what in the world??? It said: 7! The camera hadn't been used for over 24 hours and it's on the JPEG full-frame NORM setting (manual says: 100 images buffer size).

But it gets better: I held down the shutter, the camera took 7 pictures, the remaining buffer value went down to 0 of course, and then built back up to... 5! Now it's still at 5. What on earth is wrong with my camera buffer??? And what can I do?

Thanks a lot for any hints!
Flow

SquamishPhoto

Shoot continuously and see if its just a readout problem. If you can still burst 17 images than its just a display problem. Otherwise I don't know how much help we can be for you.

Ironheart

Your camera is broken. Send it to me and I'll make sure to properly dispose of it :-P

Page 438 in the D800 manual:
Maximum number of exposures that can be stored in memory buffer at ISO100. Drops if Optimal quality is selected for JPEG compression, ISO sensitivity is set to Hi 0.3 or higher, High ISO NR is on when auto ISO sensitivity control is on or ISO sensitivity is set to ISO 1600 or higher, or long exposure noise reduction, Active D-Lighting, or auto distortion control is on. Figures assume JPEG compression is set to Size priority. Selecting Optimal quality increases the file size of JPEG images; number of images and buffer capacity drop accordingly.

Also make sure your battery is fully charged, and I would assume if RAW+JPEG is used, it will be even lower.

macsavageg4

I had the same problem. My conclusion was SD is just too slow. After I switched my main card to a 400x CF card and that sorted the problem. SD while fast if you are shooting RAW will kill that data bus like crazy. I know I am probably missing some stuff or just assuming things. I just know the fast CF card too care of all the performance problems I was having with buffering. They are more expensive but they have crazy performance that is totally worth the price. I hope that helps at least from what I have seen in my working with the D800.

Golf007sd

@macsavageg4: Agreed. Faster memory card is your "Achilles' heel." Start with that and if you are writing both RAW & JPEG that too will kills your buffer.

sevencrossing

on a D800 using 14 bit RAW rather than 12 will slow things down a bit

Killerbob

Using a San Disk CF/SD combination, both of them Extreme Pros. I think they are rated at 100 and 95MB/s respectively. I am happy with the transfer rate, but could they be faster?

JJ_SO

Afaik, there are 133 MB/s possible, but that's only reading speed, not writing. I think the Extreme Pro is already one of the fastest available. And I don't think, 10-15% more writing speed would be a game changer.

FlowtographyBerlin

@Everyone: Thanks so much for trying to solve this for me!

As for the additional info: All the above was valid for an ISO 100 setting, and I never use RAW + JPEG mode, only either or, and then always in the settings I described above.

Plus, I'm not referring to the writing speed to the cards, but to the buffer size, what it holds.

So, I tried the thing @squeamishphoto said, result was that the buffer size went down to 4 after "recovering". WTH?

Then, I formatted both cards, and voilà: The buffer size went up to 16 in RAW mode (the value claimed in the manual) and 30 for JPEG (a lot lower than the 100 from the manual). BUT: When I fire continuously in JPEG mode, the number on the display goes down to 25 or 26 but then doesn't go any lower, but keeps flipping between 25 and 26! Meaning: It doesn't matter. Great! Solved!

So the solution was to format the cards, god knows why that had an impact on buffer size...

Ironheart

You are all 100% correct that faster cards will make the camera perform faster, however the buffer is independent of that speed. If his buffer is only showing 5 or 7 images, it means that some setting is chewing up buffer space, such as distortion control or a non-native ISO (like 110 or 150) selected by auto ISO. Having fast cards means that the buffer will drain faster, maybe so fast you wouldn't know or care that the buffer is tiny. For example if you are using 14-bit raw uncompressed files, you generate a 75MB file. The 100MB/sec card can scribble that file in less than a second, but a 30MB/sec card will take 2.5 sec to do it.
The D800 is able to buffer 16 of these 75MB files which will largely mask the speed of the cards, at least until it is completely full. However as I mention above there are several settings which will decrease the available buffer size, thereby making the speed of the card more critical.
I'd bet that either the active d-lighting or auto-ISO is the culprit. In other words, if you want to see 100 in the buffer you must set "size", not "optimal" for jpegs, an make sure all of the other things are turned off

FlowtographyBerlin

One more thing: I noticed how it does take quite a while for buffer to recover in RAW mode – pretty much congruent with the theoretical values: If a 14-bit-lossless-compressed file has something like 42 MB, and the speed of the cards is 30MB/s, that makes it ~1.5 seconds per image. That's what it feels like.

To those that have experience with faster cards:

1. Does anyone happen to know how fast the camera can actually write?

2. Does it slow down the writing process if you use both slots in that 'sync' mode (files are always written to both cards simultaneously, one as a backup)?

Thanks!

JJ_SO

1. Don't know
2. Should not be much different, as the 2nd card slot has it's own controller if I remember coreectly. But: CF cards are not as fast as SD cards, so theoretically the CF card can become a limiting factor.

FlowtographyBerlin

@JJ_SO: Thanks! Concerning the SD vs. CF speed thing: If they are both labelled the same speed, they are the syme speed, right? Or is this speed a theoretical value and in practice a 90MB/s CF card is slower than a 90 MB/s SD card?

[Edit:] Wait a minute, isn't it the other way around? I always heard that CF is the more sophisticated format, plus that at a nominal rate, the writing speed is faster than an SD?

JJ_SO

No, should be the same speed, you're right. I remembered different speeds with SD and CF, but at Extreme Pro class they are the same.

FlowtographyBerlin

Well, I don't care anymore anyway, because my camera is on its way to:

Your camera is broken. Send it to me and I'll make sure to properly dispose of it :-P

It's so great how generous the support among NRF members is, thanks @Ironheart! :-)

Ade

So the solution was to format the cards, god knows why that had an impact on buffer size...

It doesn't.

What is shown on the "remaining space" display when you half-press is the maximum of: a) the estimated remaining space in the buffer; and b) the estimated remaining space on the flash card (which is a very conservative estimate).

So the camera initially showed 7 frames as the remaining space because your CF/SD card was really full. In this case, the estimated remaining card space (7) was smaller than the remaining buffer space (16), so the remaining card space is what's displayed during the half-press.

After you formatted the card, the remaining buffer space is now the smaller of the two numbers, so that's what's being shown. Deleting images (instead of formatting) would have worked the same.

Also, in JPEG mode, a max buffer size of 30 probably doesn't have anything to do with the JPEG compression setting (optimal vs. size priority) as someone mentioned above. Rather, the quality setting is likely the determining factor. I.e., to get 100 frames in the buffer, the JPEG quality mode should be Small - Basic. You probably had it as Large - Normal.

FlowtographyBerlin

What is shown on the "remaining space" display when you half-press is the maximum of: a) the estimated remaining space in the buffer; and b) the estimated remaining space on the flash card (which is a very conservative estimate).

Also, in JPEG mode, a max buffer size of 30 probably doesn't have anything to do with the JPEG compression setting (optimal vs. size priority) as someone mentioned above. Rather, the quality setting is likely the determining factor. I.e., to get 100 frames in the buffer, the JPEG quality mode should be Small - Basic. You probably had it as Large - Normal.

Hey Ade, that might be the reason..., also it makes sense, as the buffer cannot hold more than can be written. In that way, the remaining space on the card actually does impact the buffer size, though – well, effectively at least.

As for the JPEGs, the manual says that the buffer holds 100 for setting large/normal.

Out of interest: How did you know about this info with the display? I can't even find it in the manual...

Ade

As for the JPEGs, the manual says that the buffer holds 100 for setting large/normal.

Out of interest: How did you know about this info with the display? I can't even find it in the manual...

Hmm, after some more investigating, the manual is correct re: the buffer size for JPEG Large Normal being 100 frames, so I take back part of what I wrote above.

As mentioned, the frame remaining value shown at half-press is actually a conservative estimate. For JPEG Large Normal, the estimate is around 30 frames (more or less depending on settings) -- so that's what's shown at half-press -- but if you actually depress the shutter continuously there is space in the buffer for 100 frames, just like the manual says.

(The buffer can probably hold even more than 100 frames, but 100 is hardwired as the camera's maximum continuous release -- setting d3 in the menus).

I usually have some idea (or educated guess) of how most aspects of Nikon cameras work (just from previous experience), and often when a question like this come up, I do a little testing to confirm my guess before posting the information. I did test the "card almost full" case to confirm the behavior, but didn't fully test the JPEG Large Normal buffer size until just now. Sorry about that (I don't usually shoot JPEG).

FlowtographyBerlin

Just in case anyone is interested in the actual write speed, I just discovered this excellent article:

http://www.robgalbraith.com/camera_wb_multi_page7321.html

You can even switch cameras using the menu at the top right. Enjoy!

SquamishPhoto

Nice link, thanks. :]