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Oh yes, it's Yet Another Thread about 16:9... And this post is gonna be long, but please bear with me...
As preparation for my purchase of a DVX (will someone *please* sell me a DVX100BE) I've been looking into this entire 16:9 thingy and after reading literally hundreds of posts here about 16:9, 4:3, letterboxing, squeeze, anamorphic, etc etc, I thought I'd do a summary on how to achieve the highest quality anamorphic 16:9 image with a DVX. *I*'m actually not telling anyone, I'm just summing things up, so please, all you really technical guys and gals out there, correct me if I've drawn the wrong conclusions or listened to the wrong people... Okay, here goes:
- Why shoot letterboxed, why not shoot ordinary 4:3 or squeeze mode?
Let's start with letterboxed vs ordinary 4:3: DV is a compressed format with an "upper size limit per frame" (to simplify) so the more detail/variation you have in your image the more it has to be compressed down to tape. When you have two large areas in your image that you're not going to use, it makes little sense filling them with detail that uses up valuable storage. Having those two areas completely black makes compressing those areas much more effective, leaving room for more data for the part of the image that you're actually using. Therefore, letterboxing in camera gives better quality images than letterboxing in post. (It's been remarked that if you letterbox in post, you get more freedom on how to frame the shot while editing since you can shift the frame vertically and still have image data there, but hey, all you're doing then is covering up for bad framing when shooting. And you're doing it on the expense of image quality...)
Squeeze mode then: when you're using squeeze mode, the DVX actually letterboxes the image and then *stretches* the letterboxed image to fit the entire frame (giving it the anamorphic dimensions). When in squeeze mode, you're not using any more of the actual image data (pixels, resolution, ccds, whatever) then you do in letterboxed, it's just stored differently, stretched, on tape. And since we're stretching the image before storing it, the compression limits from above still apply and you're now wasting storage compressing derived, from stretching, data. There's also another, even bigger, reason to why you should stretch in post instead of in camera: the camera's stretching algorithms must be able to do 50 stretches per second (60 for NTSC). The algorithms aren't doing a bad job but in the end, guess which stretching algorithms produces the best results: the camera's 3-4 year old ones that has to do a stretch in 1/50th of a second or a newly developed software algorithm that can take several seconds per frame stretch...? (Someone mentioned that the camera might stretch in 4:4:4 which would be better than a post stretch done on less color information, but I haven't seen anyone verifying that fact. But even if it is so, my money would still be on the software stretch algorithms...)
- Why edit before stretching? Why not just stretch all my raw footage and then edit?
Well, time and space. The more data you stretch, the longer it will take and the more storage space you'll need on your editing system. But if you've got the time and space and rather stretch all your raw footage, well, good for you...
- Why stretching before color correction and effects?
Stretching increases noise, which color correction sometimes introduces/enhances, and stretching your "effect data" is unnecessary since you can just as well apply the effect on the stretched material and not risk loosing quality in your effects.
- But what about using an anamorphic lens? Is that better than doing it this way?
Yeah, I would think so. With an anamorphic lens you get more actual image data which should result in better quality images (even though you've then got more data that needs to share storage during compression). If I actually had a DVX to test with, I'd be able to say for sure. (Could someone *please* sell me...)
Well, there you have it. You've made it to the end. Congratulations. Now, if you're one of the technical people, could you please let me know if I've understood all this correctly...
Oh yeah, had another question: When you're using a 35mm adapter, such as SGPro, are you then using it with an anamorphic lens between the DVX and the adapter or do you need an anamorphic lens at the end of the adapter? Or do you perhaps loose the anamorphic option then due to lack of (reasonably priced) lenses?
That's it for now.
As preparation for my purchase of a DVX (will someone *please* sell me a DVX100BE) I've been looking into this entire 16:9 thingy and after reading literally hundreds of posts here about 16:9, 4:3, letterboxing, squeeze, anamorphic, etc etc, I thought I'd do a summary on how to achieve the highest quality anamorphic 16:9 image with a DVX. *I*'m actually not telling anyone, I'm just summing things up, so please, all you really technical guys and gals out there, correct me if I've drawn the wrong conclusions or listened to the wrong people... Okay, here goes:
- Shoot letterboxed!
- Import into a 4:3 project in your NLE of preference and edit.
- Export your timeline as an image sequence and use a good resizing software, such as Photozoom, to crop and stretch your images to the proper 16:9 anamorphic dimensions. (Some prefer to do cropping and stretching directly in the NLE but the majority seem to think Photozoom gives better results due to better resizing algorithms.)
- Import the resized images into a 16:9 project.
- Color correct and add effects and other fancy stuff.
- Export and burn to DVD.
- Why shoot letterboxed, why not shoot ordinary 4:3 or squeeze mode?
Let's start with letterboxed vs ordinary 4:3: DV is a compressed format with an "upper size limit per frame" (to simplify) so the more detail/variation you have in your image the more it has to be compressed down to tape. When you have two large areas in your image that you're not going to use, it makes little sense filling them with detail that uses up valuable storage. Having those two areas completely black makes compressing those areas much more effective, leaving room for more data for the part of the image that you're actually using. Therefore, letterboxing in camera gives better quality images than letterboxing in post. (It's been remarked that if you letterbox in post, you get more freedom on how to frame the shot while editing since you can shift the frame vertically and still have image data there, but hey, all you're doing then is covering up for bad framing when shooting. And you're doing it on the expense of image quality...)
Squeeze mode then: when you're using squeeze mode, the DVX actually letterboxes the image and then *stretches* the letterboxed image to fit the entire frame (giving it the anamorphic dimensions). When in squeeze mode, you're not using any more of the actual image data (pixels, resolution, ccds, whatever) then you do in letterboxed, it's just stored differently, stretched, on tape. And since we're stretching the image before storing it, the compression limits from above still apply and you're now wasting storage compressing derived, from stretching, data. There's also another, even bigger, reason to why you should stretch in post instead of in camera: the camera's stretching algorithms must be able to do 50 stretches per second (60 for NTSC). The algorithms aren't doing a bad job but in the end, guess which stretching algorithms produces the best results: the camera's 3-4 year old ones that has to do a stretch in 1/50th of a second or a newly developed software algorithm that can take several seconds per frame stretch...? (Someone mentioned that the camera might stretch in 4:4:4 which would be better than a post stretch done on less color information, but I haven't seen anyone verifying that fact. But even if it is so, my money would still be on the software stretch algorithms...)
- Why edit before stretching? Why not just stretch all my raw footage and then edit?
Well, time and space. The more data you stretch, the longer it will take and the more storage space you'll need on your editing system. But if you've got the time and space and rather stretch all your raw footage, well, good for you...
- Why stretching before color correction and effects?
Stretching increases noise, which color correction sometimes introduces/enhances, and stretching your "effect data" is unnecessary since you can just as well apply the effect on the stretched material and not risk loosing quality in your effects.
- But what about using an anamorphic lens? Is that better than doing it this way?
Yeah, I would think so. With an anamorphic lens you get more actual image data which should result in better quality images (even though you've then got more data that needs to share storage during compression). If I actually had a DVX to test with, I'd be able to say for sure. (Could someone *please* sell me...)
Well, there you have it. You've made it to the end. Congratulations. Now, if you're one of the technical people, could you please let me know if I've understood all this correctly...
Oh yeah, had another question: When you're using a 35mm adapter, such as SGPro, are you then using it with an anamorphic lens between the DVX and the adapter or do you need an anamorphic lens at the end of the adapter? Or do you perhaps loose the anamorphic option then due to lack of (reasonably priced) lenses?
That's it for now.
.
