HDMI Output and Settings on EM1 mkii

Wairoakid

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Oct 3, 2012
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I am using an ATOMOS Ninja Flame to record the HDMI output from my EM1-Mkii. All the recording is done on the ATOMOS which means I do not push RECORD on the camera. I set the camera to video ( so I can get a feed without the overlay). The HDMI output is the video specification I selected in the video settings i.e Ck4 or FHD 50p etc. This is recognised by the ATOMOS. Audio is output in the HDMI feed. I either use M or P as the camera mode.
Whilst everything has worked well I am still a bit confused as to the effect of shutter speed. It seems that as I am not recording with the camera internal process then setting a shutter speed is irrelevant ( except for exposure). I was using the rule of thumb of doubling the frame rate as the shutter speed i.e CK4 24fps means a shutter speed of 1/48 and 50p means a shutter speed of 1/100.
However i can't see how this makes any difference as the shutter is not in operation. I think the ATOMOS is just taking the HDMI feed say at 50p and using that frame rate to record with. So shutter speed is irrelevant for this purpose and I can control exposure with ISO and Aperture
Am I right?
 

barry13

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Hi, AF cameras normally keep the aperture wide-open until the shutter is pressed, to help AF and the live view.
It's possible that video mode may do something different though, and a manual lens would give you control.
 

Wairoakid

Mu-43 Regular
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Oct 3, 2012
Messages
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Shutter must be in operation! When you use a setting eg CK4 24ps a shutter speed would be set with it I believe. And double frame rate is the norm. Have you seen this video?
Thanks I have seen this video. They do not show any settings of exposure or shutter speed just how to get HDMI without the overlay and how to select the resolution etc of the video. It really is meant to show that you get better dynamic width using the ATOMOS and Prores 422 settings than the internal compression to the SD card.
 

Wairoakid

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Joined
Oct 3, 2012
Messages
37
You need to set your shutter speed at 50th for 25fps (double frame rate) and use ISO or aperture to adjust exposure as you mentioned.
If you want your motion blur to look normal, you should take your frame rate and double it.
Thanks for taking time to reply. I will continue to set the shutter speed as you stated ( and as i do ) but I am no wiser how that impacts the HDMI feed out of the camera as I do not push the RECORD button on the camera just the record button on the ATOMOS. For a still photo the shutter speed obviously determines the length of time the frame is exposed for a picture and this occurs when the shutter is pushed (and the variants of capture in the Olympus).

Interestingly if you have Flicker Scan on and the S mode then when in video mode you can adjust shutter speed in 1/10ths of a second 50.1, 50.2 etc.

I am going to do a bit of experimentation with going outside the double rule of thumb to see what effect it has ,if any.
I am using the ATOMOS for its built in time lapse recording so saving i hope shutter wear on the camera.

Thanks again for replying.
 
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