Olympus-OM
[Top] [All Lists]

Re: [OM] Live view operation, was: E-thingy body recommendation

Subject: Re: [OM] Live view operation, was: E-thingy body recommendation
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Wed, 30 Jun 2010 19:40:53 -0400
Yes, I fully expected that there would be a very short blackout due to 
the shutter if not the mirror.  A full-frame sensor (referring to sensor 
type, not size) does need a mechanical shutter to be able to dump the 
charge.  But I still couldn't believe that was happening until I went 
back to the E-620 page and watched (by accident) the normal AF operation 
wherein we know for sure the mirror is flipping up and down.  Even so 
there is no visible blackout there either.  So there is something 
peculiar about the frame timing or something I don't understand that 
makes the E-620 videos different from the others.  All the others show a 
significant blackout period.

But we know for sure from Rickard that his 520 pumps that silly mirror 
up and down regardless.  I'll assume the 620 does it too... it's just 
that I can't see it happening on the video.

Chuck Norcutt


Moose wrote:
> On 6/30/2010 1:49 PM, Chuck Norcutt wrote:
>> Umm, as I view that video
>> <http://www.dpreview.com/reviews/olympuse520/page7.asp>  it seems to me that 
>> the E-520 very much drops the mirror even in Imager AF mode.
>>    
> 
> They were there, and presumably could hear/feel whether the mirror 
> dropped. I have no reason to mistrust them. My experience of cameras 
> I've had is that their tests are remarkably through and accurate.
> 
> All mirrorless digicams have a blackout of video feed between the time 
> the shutter is pressed and the time the processed JPEG is displayed on 
> the LCD screen. It's inherent in current technology, which requires a 
> reset of the sensor and mechanical shutter operation for still shots. 
> Still cameras with the ability to capture a still frame during video 
> capture have a brief lacuna in the video when the still is taken for 
> that reason (1 sec. on the 5DII). Pure video cameras don't, at least 
> mine doesn't, as it simply captures a frame from the stream, but that's 
> because the sensor system is different.
> 
> Certainly all mine have had blackouts of various length. With the G11, 
> it is quite brief, but certainly there. With early digicams, it was 
> sometimes tediously long. It's possible it isn't visible on the screen 
> with short shutter speeds on some cameras with fast processing.
> 
> In the case of a DSLR, , the focal plane shutter usually has to close 
> then open-close to capture the image. The usual process is that the 
> shutter closes, the sensor is reset, the shutter is re-cocked, opens and 
> closes for the exposure, then the second curtain is re-cocked with first 
> curtain open for LV and second curtain open, ready to start the next 
> cycle. The close, re-cock, expose, close cycle must briefly cover the 
> sensor twice. So two blackouts of video feed from sensor for LCD screen 
> occur.
> 
>> The E-620 seems to behave differently.  There's no blackout period.
>> <http://www.dpreview.com/reviews/olympuse620/page8.asp>
>>    
> 
> The 5DII has alternate LV "silent shooting" modes that use an electronic 
> shutter, whatever that is, to eliminate the first close-open cycle for 
> sensor reset. That would eliminate the first shutter related blackout. 
> If processing of the JPEG for screen viewing is fast enough, the second 
> curtain blackout might not be visible. Remember, by default, unless you 
> change it, the first thing seen after the shot is taken is the captured 
> image, not live feed.
> 
> Perhaps the E-620 is doing something similar. Hard to tell from the 
> static DPR test subject. You'd think 1/20 sec, plus curtain travel time 
> would show on the video, but if the video frame rate of the screen is 
> slow, it might not.
> 
> It could also simply hold the existing screen image for moment, to cover 
> the blackout, a cosmetic solution. Oly will never tell. One could try 
> testing by taking a long exposure on an E-620. IF the LCD blacks out 
> during the actual exposure, the lack of blackout on shorter exposures 
> may be simply fast image processing. If it doesn't black out, they are 
> 'cheating'.
> 
> In any case, shutter operation does mean at least one, and usually two, 
> breaks in sensor availability for live image feed to the LCD, even if 
> the mirror doesn't flap.
> 
> Moose
-- 
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz