shutter on or off

[Piotr Wozniacki]

Originally Posted by Dominik Seibold

Sorry, but you are wrong. 720/50p with shutter-off gives 1/50-shutter.

No, the slowest selectable shutter-speed depends on your framerate. But it's always faster than 1/fps or 360°, because else the electronic shutter wouldn't have a job to do and then it wouldn't make any difference if it is turned on or off.

I stand corrected, Dominic (I don't have my EX1 with me at the moment, as it's with the Prime Support for an overhaul) - with 720/50p, it should be 1/50th, same as the fps.

As to the slowest selectable shutter speed, I only meant standard shutters - not the SLS, or EX Slow Shutter.

[Dominik Seibold]

Originally Posted by Piotr Wozniacki

As to the slowest selectable shutter speed, I only meant standard shutters - not the SLS, or EX Slow Shutter.

I just tried all standard-framerates and got that result:
fps slowest-shutter
24 1/32
25 1/33
30 1/40
50 1/60
60 1/60
Interestingly at 60fps the slowest selectable shutter-speed equals the framerate.

[Steve Phillipps]

Quote:
Originally Posted by Serena Steuart
Perhaps you're saying that 50i is actually 50P and the fields for 50i are derived from alternate frames?

Exactly

Are you sure about that? 1080/50i can't be 1080/50P and fields derived from those frames 'cos the camera can't do 1080/50P. Surely 50i is derived from 25P, with alternate lines extracted to make 2 fields.
Steve

[Raul Rooma]

As i understand,25p with ''shutter off ''means 1/25 th shutter.And because of that indeed lowest shutter setting with ''shutter on'' is 1/33.you can see it if u set at 25 p shutter on or off..picture much brighter with ''shutter off''..

RR

[Dominik Seibold]

Originally Posted by Steve Phillipps

1080/50i can't be 1080/50P and fields derived from those frames 'cos the camera can't do 1080/50P.

Yes it can! It can't bring it on the sxs-cards, but it captures and processes it.

Originally Posted by Steve Phillipps

Surely 50i is derived from 25P, with alternate lines extracted to make 2 fields.

Even if the sensors would support temporal delayed odd (or even) rows, it's not a good idea, because then vertical low-pass-filerting wouldn't be possible, so it would flicker a lot on interlaced screens because of the very good MTF of the sensors+lens (the sensors don't have an appropriate optical low-pass-filter, so progressive images are very sharp). And observation shows, that it does vertical filtering on the whole 1080-rows-frames.
And what about 720/50p? If it would be derived from 1080/50i, then there would be deinterlacing-artifacts.

[Dominik Seibold]

Originally Posted by Raul Roma

As i understand,25p with ''shutter off ''means 1/25 th shutter.

Yes. To be more exactly, shutter-off means the additional electronic shutter is turned off. Then the exposure time is just the result of the periodic readout and reseting of the pixels, which depends only on the framerate.

[Steve Phillipps]

Not arguing with you Dominik, but where did you find out that the EX can do 1080/50P? I thought that was just the F23. Surely if the sensor could do it then it could feed it out of HD SDI and with the Flash XDR you'd have an F23/SR kit (more or less!) for £5000 instead of £100,000.
Steve

[Dominik Seibold]

Originally Posted by Steve Phillipps

where did you find out that the EX can do 1080/50P?

I read it somewhere, but I can't remember where. But more importantly it makes perfectly sense and matches perfectly with all of my experience.

Originally Posted by Steve Phillipps

Surely if the sensor could do it then it could feed it out of HD SDI and with the Flash XDR you'd have an F23/SR kit (more or less!) for £5000 instead of £100,000.

For sure it can be hacked. But why doesn't Sony offer it out of the box together with recording of 4:2:2 and 50MBit/s? And why do I have to use these ridiculously overpriced sxs-cards for the little throughput of 4 MByte/s, of which almost every other flash-memory out there is capable of? Hmm, I guess it could be concerned with their marketing-strategy. ;)

[Steve Phillipps]

I agree with your sentiments. I've got a PDW700 and wonder why they won't put 160 mb/sec I frame on it as seeming the mpeg used is capable of it as it's the same one used by the Flash XDR.
Still very dubious about the 1080/50P though, AFAIK it certainly does not come out of the HD SDI. Having said that, my PDW700 apparently has the same chip as the HDC1500 studio camera and that can do 1080/50P which mine can't so maybe it's a similar situation?
Steve

[Ted OMalley]

Originally Posted by Dominik Seibold

And why do I have to use these ridiculously overpriced sxs-cards for the little throughput of 4 MByte/s, of which almost every other flash-memory out there is capable of?

I'm waiting for that firmware upgrade that let's me overcrank 1080 24p to 60p! Okay, I'm not exactly holding my breath.

[Serena Steuart]

Originally Posted by Dominik Seibold

50i also gives higher sensitivity, because the 50i-setting adds gain, to exploit the lower noise-level caused by the vertical low-pass-filter for reducing flicker.

If I were putting together an opinion on this I'd suggest that the greater gain in 50i is achieved by stacking frames. If you take 2 frames (50P) to output one, then there is no point in throwing away data that can be utilised. This is how we do it in astronomy. I'm very wary of technical arguments based on "I read it somewhere". References please.

EDIT: While my point may seem "aggressive", it arises from long experience in technical discussions where difficulties often arise because people fail to differentiate between what they think and what they know. It is extremely important to make clear what is fact and what is deduced or thought to be so.

[Robert Bale]

Hi People,

I just wanted to get back to the subject, if i have the camera set to 720p50 and the shutter off, is the shutter speed 1/50 ?

I have tried both setting and can not seem to see the difference, any one have a idea what is better ?

rob.

[Serena Steuart]

Yes, shutter off when shooting progressive 50P is 1/50 sec. However that is not stated in the user manual and in accordance with my note above I add "I believe that to be so".

[Robert Bale]

Thanks for your comments.

[Serena Steuart]

OK, I've made some measurements. At 25P shutter off is 1/25. At 720/50P the default shutter is 1/60 (shutter on), which may be the reason you could see little difference between on/off. Shutter off is 1/50. I suppose I should repeat for 50i.

edit: yes, 50i shutter off is 1/50.