Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80

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    Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80
    « on: 24 / February / 2012, 10:34:17 »
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    I wasn't sure where to put this topic, so I went for General Discussion - but tell me if it should be moved elsewhere.

    I have an SD1100 and an SX230. I installed the fast MD scripts on each of them, although they are of course slightly different versions - the SD1100 has a script installed about 3 years ago, and it has separate scripts for MDpic and MDvid. The SX230 has a script I just installed and it is the one for cameras with a separate video button. So I'm not sure if its fair to compare them?

    Anyway, I assumed that my newer fancier camera with a bigger lens would trigger faster, say for lightning etc. But I just set up both cameras and tested dropping things in front of them, and to my shock it actually seems like the SD1100 is triggering faster. But, maybe I am doing something wrong. I made sure all the MD script settings were the same (columns, rows, threshold, etc). But one problem is that each camera has different options in terms of auto modes, manual modes, etc, and there are a lot of variables. Still, I've tested a couple modes, and it seems like the SD1100 is consistently triggering faster. Any idea why that is? Or how to make the SX230 faster? I want to use it for lightning photos, though its not the right time of year yet.
    My Flickr Page
    I use the chdk on my SX230 and SD1100 cameras, and I installed them using a Macbook, currently running 10.6.8.

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    Re: Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80
    « Reply #1 on: 24 / February / 2012, 13:22:15 »
    it seems like the SD1100 is consistently triggering faster.

    Well now .. I assume the script keeps the shutter button half-pressed until motion is detected and then fully presses.
    For stereo synch, we fully press the button and pause the capture sequence until the switch is released.
    With multiple cameras the photos are usually taken within a fraction of a msec of each other.
    This allows stereo images of fast action to be captured.

    A friend has just tested the synch of the SX230HS, it is really bad, about 20 msec.
    That may not seem much but for general stereo photography it is useless.

     
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    Any idea why that is?

    No.

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    Or how to make the SX230 faster?

    No, that is the big question.

    Even worse, maybe all new cameras will be just as bad.
    « Last Edit: 24 / February / 2012, 13:23:53 by Microfunguy »

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    Re: Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80
    « Reply #2 on: 24 / February / 2012, 14:03:54 »
    I wonder if this is something that could be fixed by changing the script, or is it just a limitation of the camera? If its an issue with the script maybe I should post in the thread for the MD script, but if its just the camera then I don't know.

    Also, are there any built in camera settings that would affect this? I thought for a moment about things like shutter speed, but I believe that is the length of time the shutter stays open, not the length of time from pressing the button until the shutter starts opening. So it wouldn't be relevant, right?

    I think I will try to test this further. I'm not at home right now, but I imagine I could make a video that flashes various screens at various speeds, that say things like "this screen was flashed for .1 seconds" or whatever ,and see what triggers each camera. I'll have to figure out what software I can use to make such a video accurately... Earlier today I was just testing by dropping items in front of both cameras, and there was a clear difference between the two.
    My Flickr Page
    I use the chdk on my SX230 and SD1100 cameras, and I installed them using a Macbook, currently running 10.6.8.

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    Offline philmoz

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    Re: Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80
    « Reply #3 on: 24 / February / 2012, 14:48:24 »
    I wonder if this is something that could be fixed by changing the script, or is it just a limitation of the camera? If its an issue with the script maybe I should post in the thread for the MD script, but if its just the camera then I don't know.

    Also, are there any built in camera settings that would affect this? I thought for a moment about things like shutter speed, but I believe that is the length of time the shutter stays open, not the length of time from pressing the button until the shutter starts opening. So it wouldn't be relevant, right?

    I think I will try to test this further. I'm not at home right now, but I imagine I could make a video that flashes various screens at various speeds, that say things like "this screen was flashed for .1 seconds" or whatever ,and see what triggers each camera. I'll have to figure out what software I can use to make such a video accurately... Earlier today I was just testing by dropping items in front of both cameras, and there was a clear difference between the two.

    http://dataghost.com/chdk/md_meter.html

    Phil.
    CHDK ports:
      sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
      g12 (1.00c, 1.00e, 1.00f & 1.00g)
      sx130is (1.01d & 1.01f)
      ixus310hs (1.00a & 1.01a)
      sx40hs (1.00d, 1.00g & 1.00i)
      g1x (1.00e, 1.00f & 1.00g)


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    Offline fe50

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    Re: Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80
    « Reply #5 on: 25 / February / 2012, 11:27:18 »
    I ran the webbased meter at http://dataghost.com/chdk/md_meter.html (The other two available for download didn't work on my mac). The results weren't entirely consistent from shot to shot, but the SD1100 was consistently in a faster range than the SX230. The SD1100 ranged around 60-100, while the SX230 ranged around 90-120 (once it caught a grey 80 just barely). So it does seem like the SX230 is slow. I guess the next step is to play with camera settings and see if anything makes a difference - are there any obvious settings that might? Off the top of my head I can't think why anything like aperture or whatever would make a different in triggering speed.

    I mainly wanted to use this script to capture lightning, and I doubt it will be fast enough for that, since my SD1100 is already barely fast enough to catch the longest lasting bolts (and in fact I've always wondered whether it is really doing that, or is only being triggered by one bolt and catching the next). But, its not too big of a disaster - I've already been wondering whether I'd have better luck doing some sort of (long exposure?) intervelometer for lightning and I will have to experiment with that when the storms come. This does seem like its probably fast enough to catch things like birds coming to a bird feeder, which is the other use I've had for MD scripts in the past. If I don't think of anything else in the meantime, I'll definitely report back once the summer lightning storms start happening.

    Mainly, I'm just surprised. I assumed this camera would be faster since its more powerful in general. And in fact when I take pictures by hand, I've had the sense that it is a little faster, but that's harder to quantify and maybe was just excitement bias. It certainly can take clearer photos on fast shutter speeds in low light because of having a larger lens, but I guess that is separate from the amount of time it takes to trigger the photo in the first place.
    My Flickr Page
    I use the chdk on my SX230 and SD1100 cameras, and I installed them using a Macbook, currently running 10.6.8.

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    Re: Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80
    « Reply #6 on: 25 / February / 2012, 12:00:00 »
    > I assumed this camera would be faster since its more powerful in general.

    Maybe that is why it is slower in capturing the shot, though I cannot think what else it has to check in those last msec.

    I also don't see how it could be other tasks interrupting it in such a consistent way.

    Maybe, the still image capture time is determined by a hardware interrupt timer for some reason.

    Maybe the same timer the video frame capture is determined by.

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    Offline reyalp

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    Re: Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80
    « Reply #7 on: 25 / February / 2012, 14:54:50 »
    The SD1100 ranged around 60-100, while the SX230 ranged around 90-120 (once it caught a grey 80 just barely).
    FWIW, the live view probably doesn't update at more than 30 fps (33ms between frames) and in my experience there's something like a 50ms delay between shoot_full being pressed and the shot actually being taken. So you are pretty close to the best case, although I guess it's possible that the SX230 is looking one frame behind the latest live view.
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    I've already been wondering whether I'd have better luck doing some sort of (long exposure?) intervelometer for lightning and I will have to experiment with that when the storms come.
    This is definitely the way to go if you are shooting when it's dark, then you can just leave the shutter open for a long time and let the strikes pile up. An example http://epod.usra.edu/blog/2012/02/lightning-display-on-ikaria-island-greece.html  (they ran an intervalometer with 20sec exposures, and then stacked the results )

    The nice thing about MD is that it will catch lighting in the day. Of course if you just ran an intervalometer in an active storm you'd get some too.
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    Mainly, I'm just surprised. I assumed this camera would be faster since its more powerful in general.
    Quite a bit of the remaining MD don't really depend on raw processing power. The only thing that depends on processing power is actually looking at the live buffer. The sx230 has a higher resolution live view, which could negate the difference in processing speed.  You can reduce the time cost of this by making the pixels step bigger setting bigger.  For lighting, the whole scene is probably going to change, so you don't need a lot of precision. Changing this from 6 to 10 seemed on my d10 seemed to lower the minimum time from ~110 to ~90, although I didn't run a lot of tests.

    The Y mode should be quickest, and is probably the best choice for lightning.

    Masking some of the area would probably be OK too.

    Hmmm, for lighting and similar, we could probably just make a mode that monitors Bv and doesn't even look at the live view.
    Don't forget what the H stands for.


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    Re: Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80
    « Reply #8 on: 25 / February / 2012, 19:23:17 »
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    So you are pretty close to the best case

    What do you mean? What is the best case? There is a noticable difference between the cameras, in terms of which catches an object dropped in front of them for example.

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    This is definitely the way to go if you are shooting when it's dark, then you can just leave the shutter open for a long time and let the strikes pile up.

    There are two problems with that. One, I'm in a city, so there's always ambient light, streetlights, window lights, etc. Not sure how much of an issue those would be, actually, I haven't tested it with the new camera. The other problem is that the storms often do come by before its fully dark out. Maybe an ND filter would help? I don't know if there's a good way to attach one on the front, but since the camera doesn't need to move for lightning maybe I can just tape it on there or something ;-)

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    You can reduce the time cost of this by making the pixels step bigger setting bigger.

    In the MD script settings? And what is the Y mode you mentioned?
    My Flickr Page
    I use the chdk on my SX230 and SD1100 cameras, and I installed them using a Macbook, currently running 10.6.8.

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    Offline reyalp

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    Re: Comparing trigger speed of cameras SX230 and SD1100 / IXUS 80
    « Reply #9 on: 25 / February / 2012, 19:59:46 »
    What do you mean? What is the best case? There is a noticable difference between the cameras, in terms of which catches an object dropped in front of them for example.
    I'm not saying there isn't room for improvement, just not a huge amount.
    Quote
    In the MD script settings? And what is the Y mode you mentioned?
    Yes. In mdfb, there are settings
    "pixel step" - this means that instead of checking every pixel, it checks every Nth pixel. Bigger numbers will be faster, but more likely to miss something. For lightning, you probably don't need super fine resolution, because the whole scene will get brighter.
    "channel" - controls what YUV element or color channel it looks at. Y is brightness. The YUV values are quicker to compute, since the display is in YUV format. I'm not sure how significant this is.
    Don't forget what the H stands for.

     

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