SDI monitoring speed

[Brett Harrison]

Has anyone tested SDI out delay on the Gemini (and more recent releases)? I hope with the faster rolling shutter that something like this would be increased also.

The delay on the REDs I've tried somewhat recently is a few frames slower than the ARRI SDI out - perhaps just under half a second in total. This makes a lot of difference when filming action or responding to movement on a tight lens - it's the difference between staying with the action and just catching up.

It's easy to test for yourself. Just place the LCD next to an SDI out monitor and notice the delay when flicking something into frame.

 

[Michael Lindsay]

Hi Bret

Where you using the same monitor on the arri as the red when you tested ? and what monitor was it? Was the Alexa set to psf?

I ask because some monitors perform so much better/faster with PSF frames... which red does not do?

 

[Brett Harrison]

Hi Michael,

I am not aware of the PSF status of the monitor - SmallHD and Transvideo monitors are my reference.

Does RED do PSF? How much of a performance increase does this entail?

Hi Bret

Where you using the same monitor on the arri as the red when you tested ? and what monitor was it? Was the Alexa set to psf?

I ask because some monitors perform so much better/faster with PSF frames... which red does not do?

 

[Tom Gleeson]

Bret,

No Red cameras only output progressive and no PSF. There is definitely a delay on the SDI output but half a second? We did a show with puppets and the puppeteers could not used the Red camera outputs due to the delay and we had to set up old DV cameras for the performance monitors. Why not test it and get an exact number? Point the camera at a mirror with the LCD turned to the mirror. Shoot a slate or a flash. Sorry my camera is away.

 

[Brett Harrison]

Hi Tom,

That's a very interesting thing that the puppeteers needed more response. In a way, a camera person is tracing the movement of the actors and is in a sense an animator, looking at the 'squash' before a movement 'stretches', to predict action.

Perhaps half a second is an exaggeration, but where ARRI might have a 2-3 frame delay, RED seems to have a 8-10 frame delay through SDI (the LCD connection is quite fast by comparison, roughly feels the same as ARRI).

I wish I could do a test but I don't have the cameras available. I might get a chance soon.

 

[Michael Lindsay]

Hi Brett

Yes Tom is right Red only does P...

I'll try and dig out my notes but basically some monitors are dreadful wih P and others less bad... Red's delay can be exacerbated by the monitor. For example try an older flanders CM OLED monitor with P signal then switch to PSF and the difference is easy to spot..

away on holiday at the min but when back I am happy to measure the difference in delay of a few different monitors (TVlogic, Small HD, Astro, Flanders CM) if it helps!?

From memory the delay was def less than 1/2 sec... some monitor have things like 'fast mode' .. worth checking?

Hi Michael,

I am not aware of the PSF status of the monitor - SmallHD and Transvideo monitors are my reference.

Does RED do PSF? How much of a performance increase does this entail?