Smooth motion / Frame rates/compression/Res?

[Mat Thompson]

Hi people.

I'm struggling to find information on this. I'm going to be hiring a camera to shoot some high frame rate stuff. I can only really afford prosumer type cams such as the Z7 and not dedicated high speed cams.

SO, what frame rates can the Z7 achieve? Also any info on resolution/compression would also be useful...although I have been told the longer the burst the greater the compression !?

Cheers
Mat

[Matt Bigwood]

Hi Mat

The Z7 instruction book states that the slow motion recording times can be set at 3, 6 or 12 seconds, but that picture quality deteriorates as recording time increases. The shutter speed is set to 1/215 second by default.

I remember seeing an instructional video on youtube where the presenter said it is better to shoot normally at a fast shutter speed and slow down the results in post production than use the in-built feature on the camera, though I have never tried it so can't comment on the end results.

Matt

[Mike Paterson]

The Z7 has a feature where it will shoot 120 fps for a short period - I think it's around 12 seconds. The quality is very poor however - the image is recorded 960x360 as a progressive format. Each frame is then converted to a JPEG image at 672x360. Finally the images are converted to a regular HDV signal at 1440x1080i. All the upconversion and reprocessing produces a pretty horrible result. If you're happy with 50-60 fps, hire a Sony EX or Panasonic HVX - it won't cost much more than a Z7 and will produce far superior results.

[Mat Thompson]

Hi guys
Thanks for your responses. I've seen plenty of footage shot with this feature and while its not high-definition, its seems like it would fit in a standard def time line and not look too shabby. I need over 150FPS, so without going for expensive purpose built cameras there isn't too many choices.

If have heard people mention 120fps / 160fps and even 250fps....so I was interested if anyone with one could verify this and the burst times?

[Peter Ford]

Whats nice about the Z7 is it plays back the slo mo in real time to tape, so when you import into the edit, theres no messing around- its in the same format as everything else.

However, as mentioned, the quality is dimished. If things are lit nicely, it can be acceptable. I often think the audience can be forgiving of qaulity if the subject matter is dramatic enough, - like helmet cam footage and so on.

If lit nicely, i think slo-mo from the Z7 makes good quality SD footage.

I cant tell you the frame rate, as the manual doesnt mention it. the frame rate does not change between the 2, 6 and 12 sec modes.

each mode is more compressed- i/e 6 makes footage look a little worse than 2 sec. and stuff shot in 12 sec mode is a lot more compressed than 6.

but 2 sec works out to be around 10 to 12 seconds of slo mo

and 12 sec mode works out to be about 40 or more secs of slo mo.

The way the camera works, is to record the slo mo to its internal ram, then play back the slo mo in real time to the tape.

so when you use the 12 sec mode, it has the same amount of ram, but has to fit a lot more slo-mo in it, so to accomplish this, it uses more compresion.

personally, i never use the 12 sec mode- i rarely need a 40 sec long slo motion clip.

If you use a Z7 for slo mo, id recommend ramping the shutter speed up really high- 1000 frames or so (and obviously youll need a lot of light.) as you want each frame to look crisp- motion blur in slo mo just looks like footage slowed down in post.

Pansonic really have the over cranking thing licked though- if you can afford to, id hire something panasonic with varicam stamped on it.

just re-read your post- panaonics stuff doesnt goto the frame rate you mention. Might be worth looking at hiring a dslr- some can now do HD at silly frame rates. The higher frame rate you go though, the lower resolution. I think theres one cam that goes up to 1000 frames per sec or something silly. casio ings a bell, here we go:

http://gizmodo.com/383843/casio-exil...ingly-powerful

[Zach Love]

If you are on a budget and want really nice motion in your slow motion, this is the camera to rent.

If you want slow mo & full HD rez, rent a HVX or EX camera and shoot at 60fps. But if you go w/ one of those cameras you'll only be 50% speed. The Z7 will be 25% slow motion, and you'll see the difference.

I find that the slow-mo is AMAZING. I cannot believe that anyone would think that a fast shutter could replace a fast frame rate. Out eyes can see motion, color & contrast a lot better than resolution.

Quality isn't full HD, and you can tell, but the motion is just beautiful and I think that makes up for it. You will need a good amount of light if you don't want to gain up, so just plan for that.

Here is the low down:
120fps, shutter defaults to 1/250 (Can be closed down more).
Three record modes: 3sec burst, 6sec burst, 12sec burst. These playback at 12sec, 24sec & 48sec (respectively).
Can be set to record for #seconds before or after you hit the record trigger.
Camera buffers video internally, then plays out / records video to tape in 1080i60.

I'm pretty sure you can't record to the CF card. If it is possible, I'd love to know, but I haven't gotten it to work. You also have to turn off progressive, and have to be in interlace to turn on the smooth slow motion feature.


PM (e-mail) me if you would like to see some samples.

[Kushtrim Kadriu]

It is very easy, just before you start to shoot on the tape pres the rec button on the Memory Recording Unit and you will have the shoot on the CF wile it plays back from the camera RAM. I do it that way often, not the best results but for weeding it more than good.