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Maximum number of continuous mode shots

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Offline 74prof

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Maximum number of continuous mode shots
« on: 04 / August / 2013, 09:01:52 »
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The A540 supports continuous mode that I can set up to a maximum of 10 shots in a single burst (shutter button continuously held down.)

I found the comment below though in a review:


The A540 maintained a steady 2.3fps in continuous - shooting mode , regardless of resolution and with seemingly no limit to the number of shots .

Are they wrong, or is there a burst mode bypass to increase the potential shots beyond 10?

My apologies for raising a non-CHDK issue, although increasing burst shot totals might become a new feature.

On a separate note, with CHDK video optical zoom, I have trouble getting autofocus.  Is it as simple as half-depressing the shutter before I shoot?
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Offline 74prof

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Re: Maximum number of continuous mode shots
« Reply #1 on: 04 / August / 2013, 10:10:39 »
My error: I had been looking at the menu for stacking (depth of focus, HDR etc.).  It set a maximum of ten.  What does seem to happen though, is that continuous frame rate drops after ten shots.

There is an advisory post here that has tips for increasing the frame rate in continuous mode (July 10,2011).  All I can find though is the replies, not the original post.  The tip referenced is to drop from very fine to fine resolution.  Some A540 reviews suggest there is NSD though.

So the questions becomes whether there could be a CHDK solution.


Still unsure on the other note about autofocus access with optical video zoom.
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Offline waterwingz

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Re: Maximum number of continuous mode shots
« Reply #2 on: 04 / August / 2013, 10:22:49 »
Quote from: 74prof on 04 / August / 2013, 10:10:39
My error: I had been looking at the menu for stacking (depth of focus, HDR etc.).  It set a maximum of ten.  What does seem to happen though, is that continuous frame rate drops after ten shots.
At one point it was discovered that the number of continuous shots possible is apparently a function of the memory available to buffer those shots.  CHDK uses some of that memory so on some cameras using CHDK decreases the number of shots available.  Small memory custom builds of CHDK solved that problem.

From what I can tell,  the bottle neck in continuous shooting is the speed of writing to the camera's SD card.  It a race - the camera fills memory with new shots while trying to write the older ones to the SD card to free up memory.   That's why you see the shot rate drop after a while and its why using lower resolution images can extend the number of shots.

lapser has done a lot of work on getting continious shooting to work for long extended periods.  But AFAIK, even with his more expensive camera model he only gets a little bit more than 1 fps.
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Offline 74prof

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Re: Maximum number of continuous mode shots
« Reply #3 on: 04 / August / 2013, 10:52:15 »
I have for my A540 a couple of 4 gig standard sd cards (ie not the high speed version).  They work on my A540.  So in theory I should get a high frame rate (abt 2.6 fps), longer on my 4 gig cards than my more normal 2 gig cards?
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Offline waterwingz

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Re: Maximum number of continuous mode shots
« Reply #4 on: 04 / August / 2013, 11:08:28 »
Quote from: 74prof on 04 / August / 2013, 10:52:15
I have for my A540 a couple of 4 gig standard sd cards (ie not the high speed version).  They work on my A540.  So in theory I should get a high frame rate (abt 2.6 fps), longer on my 4 gig cards than my more normal 2 gig cards?
Its not the size of the card that counts,  its the speed.  This is normally labelled as "class".   A Class 10 card is a lot faster than a Class 4,  which in turn is faster than a Class 2.

https://en.wikipedia.org/wiki/Secure_Digital#Speed_Class_Rating
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Offline reyalp

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Re: Maximum number of continuous mode shots
« Reply #5 on: 04 / August / 2013, 14:49:38 »
Quote from: waterwingz on 04 / August / 2013, 10:22:49
Quote from: 74prof on 04 / August / 2013, 10:10:39
My error: I had been looking at the menu for stacking (depth of focus, HDR etc.).  It set a maximum of ten.  What does seem to happen though, is that continuous frame rate drops after ten shots.
At one point it was discovered that the number of continuous shots possible is apparently a function of the memory available to buffer those shots.  CHDK uses some of that memory so on some cameras using CHDK decreases the number of shots available.  Small memory custom builds of CHDK solved that problem.
I don't think this applies to a540, since the default build only uses regular heap not exmem. I just shot >80 shots on mine without any discernible variation in shooting speed.

In general, most Canon P&S do not have a significant "buffering" behavior in continuous mode: they just shoot at a pretty steady rate as long as you hold the shutter down. A few have special burst modes that are different, but the a540 doesn't. The cards block management could cause occasionally hitches.

Faster cards will probably help up to be a point, but note that A540 is pre-SDHC so it may be difficult to find fast cards that are compatible.
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Offline reyalp

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Re: Maximum number of continuous mode shots
« Reply #6 on: 04 / August / 2013, 15:02:01 »
Quote from: 74prof on 04 / August / 2013, 09:01:52
On a separate note, with CHDK video optical zoom, I have trouble getting autofocus.  Is it as simple as half-depressing the shutter before I shoot?
It's a good idea to half press until the camera focuses before you start recording.

After you use optical zoom in video, the camera should try to re-focus. You can also set an "AF key" in the video parameters menu, which will force the camera to try to re-focus when you press it. The focus scan will likely be pretty obvious in the video, everything will go out of focus for a second.

If you use this, I highly recommend assigning this to "set" rather than shutter, otherwise the camera will try to re-focus when you go to end the video, which makes it so a fast click of the shutter doesn't stop the video.
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Offline 74prof

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Re: Maximum number of continuous mode shots
« Reply #7 on: 05 / August / 2013, 12:19:10 »
In continuous mode my A540 gets about 10 shots off at the fastest speed before slowing down.  That is with the L size.  With the M size I get about 20 fast shots.  At the M2 size I get continuous fast shots.

I don't know the speed of my Eye-Fi Share 2 gig card, but I tried my 133X Datamine 4 gig card, and got the same results.

So it may be that file size is the only variable I can control.
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Offline 74prof

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Re: Maximum number of continuous mode shots
« Reply #8 on: 05 / August / 2013, 15:06:50 »
If I turn off the LCD liveview, I can get 20 fast shots at the largest file size (L).  With screen turned off, M gives indefinite continuous high speed shots.
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Offline reyalp

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Re: Maximum number of continuous mode shots
« Reply #9 on: 05 / August / 2013, 17:34:53 »
Quote from: 74prof on 05 / August / 2013, 15:06:50
If I turn off the LCD liveview, I can get 20 fast shots at the largest file size (L).  With screen turned off, M gives indefinite continuous high speed shots.
How are you timing the shots?

I was just "eyeballing" that the camera seemed to be clicking away at about the same rate. Live view was one.
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