HPX170 vs less expensive cameras for chromakey duties.

G

greg sage

Member
Leaning towards purchasing used hpx170, but it's a lot more than I'd like to spend, so just want to make sure I can't get similar quality elsewhere.

I will be mainly shooting indoor greenscreen footage for music videos which will be mainly viewed on Youtube, Vimeo, etc.

I'm still undecided if I even care about shooting 1080p, or might just do 720p.

Top priorities are quality of chromakey, and vibrant colors with clear picture and fluid motion.

I may also want to do things like fast/slowmo at some point, but most interested in the basics and video quality.

So, I've read up on 4:2:2, etc. Seems like that's what I need on the cromakey end. I'm not really clear, though, whether I can get similar results with a different camera if I'm going out uncompressed.

Since I'm always indoors, capturing to hard drive shouldn't be an issue.

In my particular case, is this the camera for me, or can I save some money with another used camera?
 
With today's tools, you can pull a good key from practically anything. That said, the HVX-200/HPX-170 will have more colorspace to start from making your job easier. So if shooting primarily greenscreen material is your goal, and you want to pull great keys with minimal effort, I highly recommend either.
 
Well, it will be well lit and all that, but concerned mainly with crispness of edges, etc.

Also quality of colors in general.

What I'm not sure of though is are some other cameras just as good in that since BEFORE they get compressed down... so possible to pull 4:2:2 and decent bitrate from them if I do by going direct to hard drive?
 
Gary Huff said:
What other cameras are you talking about?
Click to expand...

Well, I've been reading for days now trying to find viable options. A couple thoughts rambling around in my head:

If I understand correctly, the camera is not full raster at 1080p, but using some digital voodoo to make up the difference.

My first thought with that is that I'd rather just shoot in 720p then, get the crispest results I can with no bs, and that should make for nice smooth edges, right?

Upon reading up on hpx 170, though, it says

"HPX170 scans the initial image at a 1080p/60 and all camera processing happens at his level. Because of this images maintain the highest quality possible up to the final conversion for compression and recording."


Which sounds to me like it does it's digital bs to reach 1080p, and then it process AGAIN to get down to 720p. I'd guess that's where the "noise" people complain about is coming from.

It would seem on the face of it to make more sense then to just find a camera that can do full raster 720p directly and output 4:2:2, no?

Any thoughts?
 
You are not going to find any other camera in the price range of a used HPX-170 that will give you 4:2:2. The only cheaper option is an HVX-200A. The HPX-250 is a 10-bit 4:2:2 onboard camera that is full raster, and the Sony EX series cameras are also full raster, but are more expensive (even used) and will only give you 4:2:0 out without the use of an external SDI recorder.
 
Yeah, I'd love an ex or the 250, but just don't have the cash.

What about something that shoots a true full raster720p and can output 4:2:2 via direct out somehow to the computer or external drive? Via hdmi? Some other output?

I really don't know that there's much point in going above 720 if it's going to be fudged anyway. Seems like the fudging would blur things a bit and actually make the keying worse than a straightforward capture at 720.

I'm happy with 720 for output anyway as it's ending up on youtube.

Seems either a hpx170 or an xf100 will be near eachother in price. Used market is so limited. Cheapest on ebay right now is in the 2500-3k range for either.

If I absolutely have to bust the wallet to pieces, which will suit me better?


Greenscreen indoors with fluoro lighting

Some dancing and rapid movement on camera.

Relatively little need for zooming, etc.

Possible color balancing issues due to less than full pro lighting.

Output as high quality a product as possible mainly for youtube consumption.

And, of course, I'll end up changing my mind at some point and want to shoot some stuff outdoors.

Not too concerned about low light situations as videos tend to be bright and eye catching.
 
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greg sage said:
What about something that shoots a true full raster720p and can output 4:2:2 via direct out somehow to the computer or external drive? Via hdmi? Some other output?
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Not via FireWire if that's what you are thinking. Anything other than recording on-board in the camera is going to require you to purchase a recorder or device to plug into your computer to ingest from an HDMI output.
 
Do you like the Panasonic "look" (aka Pana Mojo)? Have you found examples online from the HPX170 you like?
The camera puts out a beautiful image, as long as you're not trying for crazy-1"-shallow 5D depth of field.

Perhaps focus less on raster and more on will it meet your needs (keying, color correction and grading)?
From what you've described, I think it will. And DVCPRO HD runs smoothly on modest computers, as opposed to newer, more highly compressed codecs like AVCHD, which require much more powerful computers.

And there are great deals out there to be had. Dive in- the water's nice!
 
Greg, HPX171 is 4:2:2 but, and this is a big BUT, you have to think twice in the case of HPX171. Here's why:

hpx uses 960x540 chips and then with "pixel shifting" it ups the resolution to about 650 TV lines in a matrix of 1440x1080 (if you are in PAL land).
The catch here is that the pixel shifting process ups only the luma pixels and not the chroma pixels (as I understand it). So although the chroma resolution upon pixel shifting may be around 1280x720 the chroma resolution is nowhere near this. When calculating the 4:2:2 chroma resolution from the HPX171 you have to calculate it from it's original pixel count which is 960x540.

So in the end an EX1 with a 4:2:0 chroma resolution is probably going to have more chroma resolution than the HPX171. And don't forget - chroma resolution is not all that you are after. Luma resolution counts a-lot to!

HPX171 without 4:2:2 sampling would be a totally useless camera for HD if you ask me.

Sory greg I don't want to confuse you further - I just think you should know this if you are considering the HPX171 for chroma key. The hpx171 is not sharp, it's grainy, and it has a low chroma resolution. I've shot green screen footage with it and never liked the results. I've heard from other people that they had good results but when I was shown the "results" I wasn't convinced. I guess in the end it's all up to your standards for quality (and the production value of your projects off-course).
 
Just to add to my previous post: I like the picture that the 171 delivers. I'm currently doing a 30min documentary for broadcast with it and the result I'm going to get out of it are going to be very film like. And this "film" like image is the only thing I like about the HPXs image - and it's what others are raving about to. But as I said above for chroma key work I wouldn't recommend it. A hacked GH2 would almost certainly produce much better results. And you can get it for half the price of an used 171. But I can't speak about it's fluid motion though... But I doubt that it would be bad. Seriously - consider the GH2. With the hacks you can up the bitrate to 170 Mbps !! Ask somebody if they can send you a few seconds of green screen footage from a hacked GH2. I can send you some green screen footage from the HPX that I think I got it laying around... And then compare the two...

Maybe Barry could add something to this topic...
 
KINOKS said:
Greg, HPX171 is 4:2:2 but, and this is a big BUT, you have to think twice in the case of HPX171. Here's why:

hpx uses 960x540 chips and then with "pixel shifting" it ups the resolution to about 650 TV lines in a matrix of 1440x1080 (if you are in PAL land).
The catch here is that the pixel shifting process ups only the luma pixels and not the chroma pixels (as I understand it). So although the chroma resolution upon pixel shifting may be around 1280x720 the chroma resolution is nowhere near this. When calculating the 4:2:2 chroma resolution from the HPX171 you have to calculate it from it's original pixel count which is 960x540.

So in the end an EX1 with a 4:2:0 chroma resolution is probably going to have more chroma resolution than the HPX171. And don't forget - chroma resolution is not all that you are after. Luma resolution counts a-lot to!

HPX171 without 4:2:2 sampling would be a totally useless camera for HD if you ask me.

Sory greg I don't want to confuse you further - I just think you should know this if you are considering the HPX171 for chroma key. The hpx171 is not sharp, it's grainy, and it has a low chroma resolution. I've shot green screen footage with it and never liked the results. I've heard from other people that they had good results but when I was shown the "results" I wasn't convinced. I guess in the end it's all up to your standards for quality (and the production value of your projects off-course).
Click to expand...


Yeah, I guess I'm thinking that PLUS wondering about other effects of the pixel shifting. If you think about it, we're being so careful to keep the green distinct from the foreground objects... but then we run it through a pixel shifter that blends some of the pixels together to form new ones in between. Well, that's the LAST thing one should ever be doing if the goal is to keep them separate.

That's why I'm asking about the full raster... and why I'd guess it would be BETTER to do full raster at 720p than any sort of pixel shift to get to 1080... let alone arriving at 720 by pixel shifting to 1080, and then processing AGAIN to get to 720. I'm kicking myself for even considering spending the kind of money it'd take to get a FS100, but it avoids all these issues. And if I didn't care too much about these things... then I'd just get a dvx100 and call it a day.


And yes... I do like the panasonic picture over all. The colors on panasonic cameras in general tend to be more what I'm looking for than the colors on most others. I don't know that they're completely realistic, but I'm shooting music videos... most of which will be laid over cartoon backgrounds. It ain't Schindler's List. From what I've seen on the ex, though, there's a subtle richness that's a bit more refined. Hard not to like that picture.

Man, I really need to just buy a much cheaper camera before I get in too deep.:zombie_smiley:


Ok, if not firewire... what about a cheaper camera that does full raster 720, and can output 4:2:2 via hdmi if I get the appropriate doodads?

Or... what about the xf100? I'm not much of a filmaker, so the lesser zoom, less physical lens controls thing isn't really on the top of my list. Small chip and all, but it is full raster, 4:2:2, right? All these cameras are a bit tough to find used, but I might be able to do a xf for more like $2500.
 
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If all that you need is a studio chroma key camera and you are on a low budget (how much exactly?) then I don't see why you would need such a camera as an HPX171 or an XF100.

If good mobility is not a requirement then buy something that has a decent front end and just stick an external recorder to the back-end.

Sony Z5 and Canon XHA1 should also be among your options.

I personally would probably opt for the GH2. Here is a link to a hacked GH2 keyed footage. The only thing to worry about is the skew.http://www.youtube.com/watch?v=VW7u3bbwcmo

You can get a GH2 with a one lens and 2 cards for only 1k ! I think that's the cheapest option.
 
I've been reading up on the GH1/GH2, and giving it some serious consideration. Budget is a bit flexible, but I'd really prefer to keep it under $2k for the camera. The more I save there, the more I have for the lighting, other necessities.

I may well want something more later, as I branch out a bit, but for now, I've got a couple videos storyboarded that are all greenscreen, so that would get me going.

Ultimately, I'm a musician, and while I want to have creative control and do something interesting with the videos, I don't want to spend lots of time tweaking it tot the point where I lose focus.
 
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