Setting shutterspeed to 1/50th on PAL Sony cam?? at DVinfo.net

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Old September 25th, 2003, 06:02 PM   #1
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Setting shutterspeed to 1/50th on PAL Sony cam??

Hello,

I want to set the shutterspeed to 1/50th of a secon on my PAL TRV-60.

In auto mode, it defaults to 1/60th and the digital gain kicks in. Why not 1/50th? I live in the Netherlands which is in Europe, so I don't get the 1/60th shutterspeed...

The presets LANDSCAPE and SUNSET MOON give me 1/50th, but in those modi, the autofocus won't work anymore! Al the other settings give me 1/60th or more!

Please help :)
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Old September 26th, 2003, 08:45 AM   #2
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There must be an error somewhere, Bram.
In PAL land, 1/60 shutter speed is almost impossible because the various shutter speeds are calculated from the 25 fps frame rate.

Slow 1/25 and below, standard 1/50, fast 1/100, 1/250, 1/500, etc. to 1/3000.

Are you sure it's not just a viewfinder display programming error, or did you read this in your owner's manual?
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Old September 27th, 2003, 07:15 AM   #3
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Things happen as follows:

When there is very little light, the shutterspeed defaults to 1/50th and +18db digital gain is added.

When I start moving the cam to an area with more light, the shutterspeed goes up to 1/60th and the digital gain stays +18db.

When even more light is added, the shutterspeed goes all the way up to 1/100th of a second with (again) +18db gain.

Only after this point, the digital gain is dropping to 0 when light intensity increases even more. After that the iris starts closing

I really don't get why this is happening! Why does the digital gain kicks in all the time!? Why the high shutterspeeds for no reason at all!?
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Old September 27th, 2003, 07:49 AM   #4
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The manual doesn't even mention shutterspeeds an only talks about "beach and sky" and "portrait" etc.

Coincedentely I recalled that one day I noticed a small fluctuation in exposure when enabling and disabling the steadyshot. Also in progressive mode (when there's no steayshot available) the shutterspeed would nicely stick to 1/50th...

So perhaps the steadyshot was causing the high shutterspeed? The answer is a very simple "Yes" After disabling the steadyshot I got a nice 1/50th of a second at all light conditions.

Oh, and I'd like to thank sony for not putting this in their manuals :)
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Old September 29th, 2003, 09:15 AM   #5
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That certainly makes sense, Bram.

In NTSCland, Sony's electronic SteadyShot keeps shutter speed at 1/100 and kicks the gain up if the lights go dim. That's even more annoying than 1/60.
Optical stabilizers on more expensive cameras don't do that.

I wonder why PAL SteadyShot would settle with 1/60 instead of 1/100?
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Old September 29th, 2003, 09:27 AM   #6
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Bram, do you want best of both worlds?
SteadyShot stabilizer ON and 1/50 shutter speed?

Try this:

1. Make sure SteadyShot is ON and Aperture is in Auto mode.
2. Turn Camera OFF.
3. Put lens cover over the lens.
4. Turn camera back ON with the lens cover on.
5. Switch to manual aperture and dial the iris control down 4 to 5 steps from max. Leave iris control on MANUAL.
6. Remove lens cover, adjust aperture and focus properly.

Voilà!

You should be at 1/50 shutter speed WITH SteadyShot ON.

Note: If you switch the cam OFF or go back to Auto-Iris, you must go all over that procedure again, as it will resume to its default setting, that is 1/60 (1/100 NTSC) with SteadyShot ON.
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Old September 30th, 2003, 09:17 AM   #7
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Norm's right, and I believe it's an undesirable side effect of the electronic image stabilisation. OIS doesn't need to up the shutter speed but EIS does (for technical reasons). Another reason to switch off EIS in the gloom.

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Old September 30th, 2003, 11:05 AM   #8
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Indeed EIS needs higher shutter speeds in order to get rid of motion blurr. The 1/60 shutter speed in pal allows to get an acceptable shot of a CRT computerscreen when set at 60Hz refresh.
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Old September 30th, 2003, 01:02 PM   #9
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I'm just guessing here:

Trying to justify that need for faster shutter speed when EIS is ON...
Could it be that the SteadyShot circuit needs a delay to "decide" of the proper framing for each field you expose.
For instance, in 25 fps PAL, the shutter exposes one field during the first 1/100 sec. and the SteadyShot EIS needs another 1/100 sec. or so to compare the composition of the second field to the previous one and decide whether it'll reposition its contents to match the first one... ? So it can't do better than 1/100 shutter speed inside a 1/50 sec. time lapse per field.

André, what do you think of that?

(You may use mild insults and contained laughter if my explanation is ridiculous.)
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Old September 30th, 2003, 01:26 PM   #10
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Norm, there is a perfect reason why one needs a higher shutter speed when EIS is on. Remember when the camera shakes, the image projected on the CCD is moving and each image detail gets a displacement (within a field period) depending on the shake strength (amplitude) and the exposure time (shutter speed). An EIS system "replaces" the succesive images (50 or 60 fields/sec) on the correct position where they are supposed to be when there was no camera shake.(within some limits of course). This is done by dynamically correcting the image read-out position on the CCD structure. So the image get stabilized but remains blurred (unsharp) because of this blurred fields which would occur at 1/50 exposures. A higher shutter speed (1/100 and higher) reduces the remaining blurr to an acceptable level. With OIS there is no motion (allmost) on the CCD level and thus no intrafield blurr. That's why the higher shutter speed in not needed with OIS
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Old September 30th, 2003, 01:42 PM   #11
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So it's not a question of processing delay.

...That's why the bypass procedure I suggested earlier to Bram does not inhibit the EIS, but it will only increase the risk of a certain degree of blur in the stabilised picture "forced" at 1/50.

Thanks André!
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