A65 maximum supported interface speed (for fast SD card)

Started May 21, 2012 | Discussions thread
Contributing MemberPosts: 678Gear list
Re: A65 maximum supported interface speed (for fast SD card)
In reply to AndiP, May 24, 2012

You're certainly correct that the information coming into the buffer and then processed is always in RAW form, then converted at some speed and written. So the rate at which the buffer is filled is the same regardless of output type. But on another thread talking about burst depth I tested this out a little and got the following burst depth (number of pictures before it slows down).

• 10FPS RAW- 12 shots
• 10FPS fine JPEG- 13 shots, with a 14th a fraction of a second later
• Continous High 8FPS RAW- 12 shots, with a 13th a fraction of a second later
• Continous High fine JPEG- about 16 frames.

So you do see some difference in burst depth depending on output type. It's only a frame or so at 10FPS, but if you slow down to the continous high, which is either 7 or 8 FPS, it's a litle bigger. So I think even though you're dumping 250MB/sec into the buffer at the highest speed, it's processing it and writing it out at some speed as well. For the jpeg files, they're smaller enough to be written quicker so the first couple of shots are written in the first second and you get 1 or two additional frames. At the 7-8FPS speed, it's loading up at a slower rate and clearing out at the same, so you can get a decent bump in depth by shooting in jpeg.

Somebody else in the thread did a similar test with a class 10 card, and the results were pretty much the same. RAW depth doesn't change, and I think you might get a couple more frames on continuous high jpeg but that's about it.

If the camera is writing at 25MB/sec or something like that to the card, you'd expect it to be able to write a few files in the first second on jpeg mode even at 10fps and get a maybe 3-4 frame boost in depth. The fact that it's really 1 extra frame and maybe most of a second is a probably also a sign that you do have some limitations in how fast the camera can process the first frame for jpeg conversion, corrections etc.

AndiP wrote:

In the meantime I also realized how this burst process is technically working and why it is not possible to take larger picture series (with more than 10 pictures) without interruption in such a burst eg. by setting your camera to JPG only (or even reducing the resolution of JPG pictures to 12MP)

Independent of the camera setting (RAW, RAW+JPG or JPG only) it's always the RAW pictures which are written to the cameras picture cache.

The subsequent processing for JPG pictures is based anyway on RAW files. (That means: no JPG's without RAW's)

The JPG conversion and the whole (optional) noise removal and lens compensation routines also take some time; therefore these processes will take place immediately after the burst series has been shot (and not during burst process) as it would slow down the burst process.

So independent of your setting it's always the RAW's that are captured (and therefore limit the max. number of pictures in such burst series by their size and the amount of space available in the camera cache)

If your setting is RAW: those RAW pictures are subsequently written to the SD card.

If your setting is RAW+JPG: the JPG process also takes place and both file types are subsequently written to the SD card

If your setting is JPG: the JPG process also takes place but only the JPG type files are subsequently written to the SD card.

 Spillicus's gear list:Spillicus's gear list
Sony SLT-A65 Sony DT 18-55mm F3.5-5.6 SAM Sony DT 35mm F1.8 SAM Tamron SP 70-300mm F/4-5.6 Di USD
Reply   Reply with quote   Complain
Post (hide subjects)Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow