Real world demonstration of photography flashes on EX1 footage

[Matt Davis]

Following much debate about the effect of flashes in EX1 footage whilst only seeing one bit of actual footage, I'll throw the following off-cuts into the community.

http://www.mdma.tv/ex1/flashes.html

Warning: contains flashing strobes. Fast editing. May cause seizures. May contain nuts.

It's big - 14 MB - because it's in high quality PhotoJPEG. That means you don't need the QT HDCAM-EX codec to view, and hopefully the quality is pretty close to the original.

As I get flashes usually when there's little light around, I tend to have the shutter off, and so I don't get a problem. Even when it's on, the effect is not exactly displeasing (the Delft Girls shot for example). It rolls, but not in a way that non-experts would point at and refuse to accept.

And yes, the shots are off-cuts whilst I'm framing, focusing, hunting, waiting for something to happen. This is not a demonstration of good camerawork.

[Perrone Ford]

So this is what all the fuss was about?

[Matt Davis]

Originally Posted by Perrone Ford

So this is what all the fuss was about?

LOL! Ex-actleeee!

In fact, with apologies to Chris Hurd, I am going to treat myself to a Smiley:

:-D

Anyone read Jonathan Swift recently? Big-enders vs Little-enders?

[Joe Lawry]

Wow, the EX1 has gone up a notch in my books, keep the shutter off and you seem to be all good.

Thank you very much for posting this.. now if only i could get over the ergonomics..

[Perrone Ford]

Originally Posted by Joe Lawry

now if only i could get over the ergonomics..

Ehh... it's not a shoulder cam. Put it on a tripod, or a stabilizer. Or if you want shoulder mount, put it on a Zacuto. Frankly, having 1080p and HDI out on a sub-10k camera with 10 stops of latitude is more than enough for me to ask for right now.

[Dave Morrison]

I'll add another "data point" to this discussion. Here's a few seconds of lightning I shot with my EX1. I was consciously trying to keep the shutter speeds low to overcome the rolling shutter effect. I don't remember if I ever tried the shot with shutter off but I'm not sure if that would give me a speed slower than 1/30th or 1/34th (or whatever the slowest shutter speed is).

http://www.vimeo.com/1277358

[Matt Davis]

Originally Posted by Dave Morrison

I don't remember if I ever tried the shot with shutter off but I'm not sure if that would give me a speed slower than 1/30th or 1/34th (or whatever the slowest shutter speed is).

OFF would have done it IMHO.

And for the record, I shot some lightning using a Z1 - in HDV. That's interlaced HDV.

It was unusable in interlaced mode. I have to stress this really strongly in the discussion about rolling shutter, because it relates to my rising resentment of interlaced video.

http://www.revostock.com/FileCloseup.html?&ID=4209

The original is interlaced video. Unusable. Really bad. I have to deinterlace it, and due to the rules, it has to be 720p footage, not 1080p footage.

For me, rolling shutter is 'ever so slightly' less of a problem than shooting interlaced footage. Shutter off = CCD style imaging so far.

[Dave Morrison]

Hey Matt, your footage looks more like lightning than mine does! Nice. Was it assembled out of several flashes? I've been shooting everything in 30p but probably didn't have the Shutter Off. What equivalent shutter speeds will I get under those conditions with the shutter OFF?

[Matt Davis]

Originally Posted by Dave Morrison

Hey Matt, your footage looks more like lightning than mine does! Nice. Was it assembled out of several flashes?

Aww, shucks - thanks! Several flashes? And then some - that clip is 8 flashes from a 48 minute storm. Very heavily chopped!

Originally Posted by Dave Morrison

What equivalent shutter speeds will I get under those conditions with the shutter OFF?

That was shot on a Z1 at HDV 1080i PAL, so it comes out at 25p from 50i, the shutter speed was probably 1/50th - but with CCD this point is moot. If I were doing the same with an EX1 (which I'd love to do dearly), I'd be shooting 1080p25 with shutter OFF. I'd be getting about 1/25th shutter, so dialling in ND, and iris to f4.8 or there abouts (sweet spot).

For those with Final Cut Pro, don't forget the Apple Film Tool thingy, which can convert 2fps to 24fps without recompression or other buggeration.You'll need to do audio separately, but the difference between 24fps and 25fps is only a little thicker than a cigarette paper. Progressive rules - in my book!

[Dave Morrison]

Well, that leaves me a little puzzled. I was very close to those shutter speeds (1/30th, IIRC) and shooting Progressive so I'm not sure why I got all the "banded" flashes. We're in the Summer thunderstorm pattern right now in Florida so I'll get LOTS of chances to test this out. Unfortunately, my EX1 lost it's ability to focus yesterday so that will limit my shooting a bit.....to say the least.

[Eric Pascarelli]

"Shutter Off" does not eliminate partial exposures - it just lowers their probability.

There is no way to eliminate the possibility of partial exposure at normal shooting speeds.

But as the video clips show, when a flash is only part of what lights the scene, the partial exposure seems completely acceptable.

When it's the only light source, as is the case with the lightning, it gets into the zone of unacceptable.

[Tom Roper]

Originally Posted by Eric Pascarelli

"Shutter Off" does not eliminate partial exposures - it just lowers their probability.

There is no way to eliminate the possibility of partial exposure at normal shooting speeds.

But as the video clips show, when a flash is only part of what lights the scene, the partial exposure seems completely acceptable.

When it's the only light source, as is the case with the lightning, it gets into the zone of unacceptable.

Thanks Eric. That's an understandable and helpful explanation.

[Adam Reuter]

Originally Posted by Matt Daviss

OFF would have done it IMHO.

And for the record, I shot some lightning using a Z1 - in HDV. That's interlaced HDV.

It was unusable in interlaced mode. I have to stress this really strongly in the discussion about rolling shutter, because it relates to my rising resentment of interlaced video.

http://www.revostock.com/FileCloseup.html?&ID=4209

The original is interlaced video. Unusable. Really bad. I have to deinterlace it, and due to the rules, it has to be 720p footage, not 1080p footage.

For me, rolling shutter is 'ever so slightly' less of a problem than shooting interlaced footage. Shutter off = CCD style imaging so far.

The thing is the Z1 is CCD and the EX1 is CMOS. The issue Dave is having is with the non-global shutter of the CMOS chip. That's the source of the lightning problem.

I would be interested to see you re-test some lightning footage in 720/60p mode with the shutter off though, Dave.

[Dave Morrison]

As soon as I get it back (again) from Sony Service and we get a lightning storm (almost every night), I'll give it a shock....er, shot. ;-)

[E.J. Sadler]

Your sample has four instances of half frame flashes. If it doesn't bother you then don't worry about. I find it very distracting.

The biggest problem is having no control over the flash duration. Sometimes it might not be so bad, but in other situations you could get rolling shutter issues all night.

Lightning is less of a concern because is has an average flash duration of about a 1/5th of a second. Professional strobes can be in the 1/500 to 1/12,000 range.

Try shooting a BBall game with SI strobes in the ceiling and see what happens.