> On another note, has anyone else noticed Cineform Neoscene converted clips having a slightly greenish cast compared to the original clip? Nothing that can't be corrected in Vegas, but...

NeoScene is actually the more correct output. Canon DSLRs record HD video with an SD (601) colorspace, Vegas is not correcting for this. NeoScene translates the 601 in a Rec709 standard HD colorspace so it is correct. If you shoot a deep red object, it will still be red with NeoScene but a little orange with the native decoder in Vegas. This is a common error, QuickTime and therefore FCP get it wrong too.

Here is a blog entry that covers that as well as other reasons to use an intermediate. http://cineform.blogspot.com/2010/11/why-use-intermediate-for-dslr-video.html

David Newman
CTO, CineForm

Thanks very much for taking the time to respond. Interesting read.

My question is: Am I better off setting project properties at 50p and then later rendering at 25p, or set project properties at 25p to start with (keeping in mind that the original clips are all in 50p)?

Croc, seems your questions have been answered, but I'm going to pose another for you:

I'm wondering if you'd be better off with a rendered product that is 25i, unless your finished format precludes interlaced (eg, PC playback on youtube would preclude any interlaced footage).

Here's why I'm asking:

If your source is 50p, changing the speed and converting to 25p will, depending on the method used, either:
1. Cause every frame to be a merged mess of the frames around it, or
2. Cause possibly choppy motion due to the removal of the inbetween frames.

If you make the final product interlaced, you may potentially solve the ghosting issue of option 1, because the project now has the same number of frames (fields) as the original source.

But of course, interlaced has its problems (not good for PC playback) and it's not half as popular as Progressive with all the kids these days. ;-)

You'll need to test what I'm saying - I haven't done this before myself. Just think'n out aloud.

Cheers,
Jason

My question is: Am I better off setting project properties at 50p and then later rendering at 25p, or set project properties at 25p to start with (keeping in mind that the original clips are all in 50p)?

This will make no difference in the output, but will make the preview respond differently. In this case I would set the project properties at 25p, so it will play like the output (assuming sufficient CPU performance).

In this case, discarding every other frame (with resampling disabled) is exactly the right thing to do. It is the equivalent of shooting 25p in the first place, so nothing has been "lost."

Thanks for that.

That's what I was expecting (hoping) Vegas would do - drop every second frame as though I had shot 25p in the first place - except for the clips which I have stretched for slow motion, in which all 50p are used. Before I learned about disabling resampling, it was blending the frames into a mess pretty much as described by entilza72. Disabling resampling has opened up a whole new world of crisper looking video. Now, if only I could improve my ability to keep in focus on my dslr when the animal is moving directly towards me.

Entilza72, although not a kid myself I'm definitely one of those people that favours progressive scan over interlaced. Aside from the fact that I view things either on my computer or progressive scan TV, in the past I always found it distracting, when watching any sort of action on the screen, to have the edge of the subject broken up into horizontal lines.

"In this case, discarding every other frame (with resampling disabled) is exactly the right thing to do. It is the equivalent of shooting 25p in the first place, so nothing has been "lost." "

Not so sure about that.

25p shot with a 180deg shutter is 1/50th.
50p shot with a 180deg shutter is 1/100th.

Discard every second frame and you get 25p shot with a 90deg shutter and that means more judder than normal. You now have that Saving Private Ryan look.

Bob.

.

The last camera I had with a rotating shutter was a Univex Mercury (35mm still camera).... still have it around here somewhere. Yeah, if you're shooting actual film, with the shutter spinning at frame rate, you get the equivalent of 1/50th sec shooting 25fps with a 180 degree shutter, or 1/100th sec with a 90 degree shutter. The look on film is only about the shutter speed... the rotating shutter was just a means to an end, going back to the days of hand-cranked film cameras (or my Dad's old Bolex, for that matter... spring-wound).

But I'm taking about video. If I shoot 50p on a video camera, I can choose 1/50th second per frame, 1/100th second per frame, or something else. Downsampling that 1/50th per frame video from 50p to 25p, I'm still 1/50th sec per frame... exactly the same effect as that 180 degree shutter. If I downsample video shot at 1/100th sec, then I'm going to look like the 90 degree shutter on film. And of course, the camcorder could also shoot 1/25th sec (at 25p), or 1/10,000th sec for that matter ... neither of these likely to be common settings on a film camera. Well, you can put in a faster shutter, but you can't have a 360 degree shutter :-)

Of course, if you did shoot at 1/100th second and 50p, you could get the 1/50th sec. at 25p look by blending frames with some motion blur.

And actually, I've read that "Saving Private Ryan" was shot at 1/500th sec. Again, discarding every other frame from 50p shot at 1/50th gives you 25p shot at 1/50th... it can't magically give you 25p shot at 1/100th. Yeah, it'll look less smooth, because, well, 50p has twice the frame rate... it's not a shutter-speed issue. If I shoot at 1/500th, the 24p/25p downsample will look like SPR, 50p or 60p would look a bit smoother.

Thanks to both Bob and hazydave for the explanation (and for making me go and read up on the 180 degree shutter rule, here: http://blog.tylerginter.com/?p=385 in which SPR even gets a mention).

Hazydave, I think Bob's right about the 90 degree shutter because I normally shoot at a shutter speed that is twice my frame rate, so all of my 50p video was shot at 1/100s. If I understand the 180 degree shutter concept correctly, if I were to drop every second frame it becomes 25p at 1/100s, which is the equivalent of a 90 degree shutter because the exposure is only for a quarter of the frame.

edit: I should add that my dslr will not allow me to set the shutter speed to 1/50s at 50p. The slowest I can go is 1/60s. My guess is that 1/50s at 50p would be the equivalent of a 360 degree shutter and would start to show smearing?

"My guess is that 1/50s at 50p would be the equivalent of a 360 degree shutter and would start to show smearing? "

What you call smearing is generally known as motion blur. Too much of it can look unusual or be aesthetically quite pleasing. Too little can also be used for aesthetic reasons or can look unusual. At low frame rates the motion judder is generally considered unpleasant but there's no hard and fast rules. The better video cameras let you set the shutter by angle or by speed. If you specify a 180 deg shutter then at 50p you get a speed of 1/100. Shoot 25p and you get 1/50, shoot 50i and you still get 1/50.

I have used a 360 deg shutter to simply get more light and it doesn't look all that bad at all. To get a 360deg shutter I switch the shutter "Off". Technically at a guess it wouldn't be exactly 360deg as the sensor has to reset. At very low frame rates you can use frame accumulation to get very slow shutter speeds.

One good example of the effect of shutter speed / angle is the typical sports broadcast. Fast motion can look very juddery. I believe the reason for this is because of the need for instant slomo replays.

In your case the practical difference between a 1/50 or a 1/60 shutter speed is next to nothing. One reason to try to stay with a "normal" 180 deg shutter on DSLRs and CMOS cameras in general is it can help to mask the rolling shutter artifacts.

Bob.

Again, it's all about the shutter speed. If you did shoot at 1/100th sec, then yeah, what Bob said and what I said are the same thing: you would need to blend frames from your 50p video to get 25p that looks as if it were shot at 1/50th. However, if you had shot your 50p at 1/50th (were that possible), you would get the same 25p result by dropping alternate frames.

The "smearing" you're referring to is motion blur ... the longer you leave your shutter open, the more things have a chance to move during exposure. It's just that simple. You get exactly the same blur per frame with 1/50th sec at 50p as you do at 25p. But of course, with twice as many samples, the 50p video will be smoother.