Shutter Speed Tests

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Offline hailstorm

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    Shutter Speed Tests
    « on: 27 / December / 2007, 00:59:34 »
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    Ok everyone..those who are interested..pls rev ur cams and post the details here

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    Offline e2b

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    Re: Shutter Speed Tests
    « Reply #1 on: 05 / January / 2008, 23:11:13 »
    I have tested the shutter speed override in AllBest's v16 on an A610 and an S3, WITHOUT flash. With both these cameras the fastest speed I could get was 3 x (1/100k), or approximately 1/33 000 sec.

    The method I used was to take pictures of a sheet of white paper in bright sunlight. This gives a very narrow single peak on the histogram. With the A610 I used (manual setting) F8 and ISO 200 and 400. With the S3 I used F8 and ISO 400 and 800.

    Changing the exposure time moves the peak along the histogram, one division (20% of total width) per EV change. The exposure override appeared to be accurate down to 4 x (1/100k), changing 1 EV for each factor of 2 in the Tv setting. There was a small change from 4 to 3, but I am not sure if 3 x is an accurate timing. There was no change for settings of 2 x and 1 x.

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    Offline e2b

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    Re: Shutter Speed Tests
    « Reply #2 on: 06 / January / 2008, 00:39:32 »
    I have completed the testing of the CHDK manual settings range on these cameras (AllBest's v16), checking the aperture range using the same method of shifting a sharp (narrow) peak on the histogram.

    For the A610 the aperture override works (in 1/3 EV steps) to F11 (11.3) - the limit on the camera is F8.

    For the S3, the aperture cannot be altered outside the range available on the camera (limit is F8).

    Including the ISO override tests I reported previously ( http://chdk.setepontos.com/index.php/topic,243.0.html ), the EFFECTIVE range of manual settings for these cameras appears to be as follows:

    A610: ISO 30-600 (normally 50 to 400); max shutter speed: 3 x (1/100k) secs (about 1/32 000 sec); aperture range to F11 (normally limited to F8)

    S3 IS: ISO 50-1000 (normally 80 to 800); max shutter speed: 3 x (1/100k) secs (about 1/32 000 sec); aperture range to F8 (same as normal limit of F8).

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    Offline hailstorm

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    Re: Shutter Speed Tests
    « Reply #3 on: 06 / January / 2008, 03:45:56 »
    I have completed the testing of the CHDK manual settings range on these cameras (AllBest's v16), checking the aperture range using the same method of shifting a sharp (narrow) peak on the histogram.

    For the A610 the aperture override works (in 1/3 EV steps) to F11 (11.3) - the limit on the camera is F8.

    For the S3, the aperture cannot be altered outside the range available on the camera (limit is F8).

    Including the ISO override tests I reported previously ( http://chdk.setepontos.com/index.php/topic,243.0.html ), the EFFECTIVE range of manual settings for these cameras appears to be as follows:

    A610: ISO 30-600 (normally 50 to 400); max shutter speed: 3 x (1/100k) secs (about 1/32 000 sec); aperture range to F11 (normally limited to F8)

    S3 IS: ISO 50-1000 (normally 80 to 800); max shutter speed: 3 x (1/100k) secs (about 1/32 000 sec); aperture range to F8 (same as normal limit of F8).


    HEy Barney....any explainations?????


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    Re: Shutter Speed Tests
    « Reply #4 on: 06 / January / 2008, 05:13:59 »
    I have completed the testing of the CHDK manual settings range on these cameras (AllBest's v16), checking the aperture range using the same method of shifting a sharp (narrow) peak on the histogram.

    For the A610 the aperture override works (in 1/3 EV steps) to F11 (11.3) - the limit on the camera is F8.

    For the S3, the aperture cannot be altered outside the range available on the camera (limit is F8).

    Including the ISO override tests I reported previously ( http://chdk.setepontos.com/index.php/topic,243.0.html ), the EFFECTIVE range of manual settings for these cameras appears to be as follows:

    A610: ISO 30-600 (normally 50 to 400); max shutter speed: 3 x (1/100k) secs (about 1/32 000 sec); aperture range to F11 (normally limited to F8)

    S3 IS: ISO 50-1000 (normally 80 to 800); max shutter speed: 3 x (1/100k) secs (about 1/32 000 sec); aperture range to F8 (same as normal limit of F8).


    HEy Barney....any explainations?????

    having a s3 is here. well just testing the 1/100k ... i think that is fast enough considering the darkness of the pics hehehhe .... i wonder how do you overcome the very under exposure in manual mode ??? do we need to keep going to menu to change the override or there is something we could do from the buttons ??? i assume that the normal ISO button does not work anymore ??? or do they still ??? could be use the ISO ??? but again the ISO comes the noise ???

    f8 for s3 is already degrading as the claimed golden aperture is 5.6 ...

    what are the best settings for high speed with nice exposure ???? anybody ???? for daylight and darkish lighting ?

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    Offline hailstorm

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    Re: Shutter Speed Tests
    « Reply #5 on: 06 / January / 2008, 21:42:03 »
    I have completed the testing of the CHDK manual settings range on these cameras (AllBest's v16), checking the aperture range using the same method of shifting a sharp (narrow) peak on the histogram.

    For the A610 the aperture override works (in 1/3 EV steps) to F11 (11.3) - the limit on the camera is F8.

    For the S3, the aperture cannot be altered outside the range available on the camera (limit is F8).

    Including the ISO override tests I reported previously ( http://chdk.setepontos.com/index.php/topic,243.0.html ), the EFFECTIVE range of manual settings for these cameras appears to be as follows:

    A610: ISO 30-600 (normally 50 to 400); max shutter speed: 3 x (1/100k) secs (about 1/32 000 sec); aperture range to F11 (normally limited to F8)

    S3 IS: ISO 50-1000 (normally 80 to 800); max shutter speed: 3 x (1/100k) secs (about 1/32 000 sec); aperture range to F8 (same as normal limit of F8).


    HEy Barney....any explainations?????

    having a s3 is here. well just testing the 1/100k ... i think that is fast enough considering the darkness of the pics hehehhe .... i wonder how do you overcome the very under exposure in manual mode ??? do we need to keep going to menu to change the override or there is something we could do from the buttons ??? i assume that the normal ISO button does not work anymore ??? or do they still ??? could be use the ISO ??? but again the ISO comes the noise ???

    f8 for s3 is already degrading as the claimed golden aperture is 5.6 ...

    what are the best settings for high speed with nice exposure ???? anybody ???? for daylight and darkish lighting ?

    well i tried out some experiments...agreed the fastest exposure i got is about 3/100k :(...anywys..have to find out how in thr flash pics they managed to get that speed.....
    http://chdk.wikia.com/wiki/Samples:_High-Speed_Shutter_%26_Flash-Sync

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    Offline e2b

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    Re: Shutter Speed Tests
    « Reply #6 on: 07 / January / 2008, 01:51:33 »
    I think that one reason for the differences in reported shutter speeds is that a shutter has an opening phase, a period when it is open, and then a closing phase. This means that there is always going to be some argument as to the 'true' speed. The EV change method I used is just one way of measuring 'effective' shutter speed.

    I extended the tests today to cover wider apertures. It turns out the situation is a bit more complicated with these low F numbers. Up to a certain shutter speed the EV changes with shutter speed as would be expected. Then for faster shutter speeds (smaller exposure times) the EV changes, but not as much as would be expected based on the nominal (specified) shutter speed. Finally, with even faster shutter speeds, changing the specified speed has no more effect on exposure.

    I have estimated these two limiting shutter speeds for the A 610 and S3 IS (as multipliers x 1/100k).

    For the S3 IS: F8: 4x - 3x; F5.6: 4x - 3x; F4: 8x - 4x; F2.7: 16x - 4x.

    As a specific example, at F 2.7, for exposure times longer than about 16/100 000 sec, exposures are as specified. For exposures longer than 4/100 000 sec and shorter than 16/ 100 000 sec (at F2.7) the effective exposure time is somewhat greater than would be calculated from the specified exposure time (the shutter speed is effectively slower than indicated). An indicated exposure of 4/100 000 sec is the limit for this camera at F2.7, but effectively it is significantly slower. However, at F8, this camera can provide a fastest 'true' exposure of around 4/100 000 sec.

    The A610 appears to have longer opening and closing phases, which are revealed with larger apertures (smaller F numbers): F8: 8x - 3x; F5.6: 12x - 4x; F4: 16x - 4x; F2.8: 24x - 7x

    As others have noted, the faster shutter speeds are only available at the smaller (high F number) apertures  :(.




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    Offline e2b

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    Re: Shutter Speed Tests
    « Reply #7 on: 07 / January / 2008, 22:27:06 »
    These override functions are certainly turning out to be more complicated than I had thought!

    I tested the aperture override as a function of zoom focal length (A610 and S3) with the following results:

    A610: At minimum focal length (36 mm equivalent) the highest effective F number is F11. The highest F number increases progressively with increasing focal length so that F16 is obtainable at 140 mm (equivalent)

    S3 IS: At minimum focal length (36 mm equivalent) the highest effective F number is F8. The highest F number increases progressively with increasing focal length up to about 300 mm, up to an effective F number of F11, and this value does not change as the focal length is increased further.

    I then re-tested shutter speeds with maximum apertures and highest F numbers.

    With the S3 I used auto Tv bracketing by 1/3 EV down from 8 x 1/100k. The indicated exposure decreased down to 1/3 EV faster than 4/100k (that is, close to 3/100k), but did not change beyond that point.

    With the A610 (in a similar test) I encountered a strange bug with auto Tv bracketing in which all except the first picture were greatly over-exposed (this feature works OK in other situations). I had to revert to setting the shutter speed override manually, and again I found that the fastest setting that had any effect on the exposure was 3/100k sec.

    I came across a post from Barney Fife ( http://chdk.setepontos.com/index.php/topic,101.msg1404.html#msg1404 ) and agree with his remarks about the difficulty of estimating shutter speed when using a flash for illumination. However, it seems to me that by using constant light (the Sun) instead of a flash, the exposure change method should give a reasonable estimate.

    I also agree that using a mark on a rotating disk should give a good estimate of shutter speed. However, I think it is necessary to know the particular physical arrangement of the mechanism, for example, strange effects can occur with focal plane shutters and streak cameras.

    I would be useful to put such findings into the Wiki, but I would like some independent verification first.




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    Offline e2b

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    Re: Shutter Speed Tests
    « Reply #8 on: 08 / January / 2008, 02:32:28 »
    Attached is a picture of a water drop splash, which I took today in bright sunlight. Details as follows:
    S3; override shutter speed 3/100k; override aperture F4; ISO 200.

    My conclusion is that even if the minimum exposure time is 'only' around 3/100k sec, this is fast enough to give quite a nice droplet picture.

    I put the camera on a tripod, kept the shutter button pressed in continuous shooting mode. This picture is the best out of about 100! Note the shadow of the falling water stream.

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    Offline hailstorm

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    Re: Shutter Speed Tests
    « Reply #9 on: 08 / January / 2008, 04:32:05 »
    good shot e2b.. :blink:

     

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