HPX600 and video lenses

S

steve phillipps

Veteran
Just wondering - as the HPX600 has a single sensor, how will it work with video lenses? I thought that regular ENG lenses needed 3 chip designs to work properly - this is why stills camera lenses weren't optomised for them? I thought the ENG lenses were computed to go through the beam splitter?
Steve
 
Thanks, yes I know it has standard b4 mount - I just thought that without a beam splitter the lens would have aberrations - just the same as using stills lenses on 3 chip cameras - the reason the Optec longitudinal colour corrector was invented.
Steve
 
steve phillipps said:
Thanks, yes I know it has standard b4 mount - I just thought that without a beam splitter the lens would have aberrations - just the same as using stills lenses on 3 chip cameras - .........
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Yes, you're correct. Good 2/3" lenses are designed with the beam splitter in mind, and designed to be used with such an arrangement.

I'm sure such lenses will work with HPX600 - but they will inevitably show defects that they wouldn't on a 3 chip 2/3" camera.

This subject cropped up in relation to using adaptors on an s35 camera to enable the usage of B4 lenses. The prime function of such is to spread the image to cover the much bigger area of s35, but the more expensive ones (like the Sony LA-FZB1) also correct the optics to compensate for it being single chip.

Really depends where you draw the quality line as to whether it's good enough - but it won't be as good as on a 3 chip 2/3" camera. Hardly surprising - that's what the lenses are optimised for in design. AFAIK, the HPX600 is the only single chip 2/3" camera.
 
Possibly the CAC software may be being used to correct any aberrations but there is so little about the HPX600 it would need a good test to see what the results are.
 
AFAIK the CAC software is for lateral chromatic aberration rather than longitudinal?
Conversely, and of interest to long lens shooter, presumably stills lenses should work perfectly with the 600?
Steve
 
The Silicon Imaging SI-2K also uses a single 2/3" CMOS chip. A quote from their website:

The Silicon Imaging SI-2K uses a single large 16:9 format 2/3” CMOS sensor, with it's design enabling the use of lower-cost 16mm film-style lenses, eliminating the optical aberrations caused by a 3-chip prism assembly.

It seems to be optimized for cinema lenses, although I've seen B4 type zooms on film cameras, like on NFL Films cameras.
The original RED Scarlet design was a 2/3" chip, fixed zoom camera.

But look at the videos I included above. How does it look to you? The shooter said he didn't notice any issues with a single CMOS chip. The videos look fine to me. Perhaps a lab test will bring out any aberrations, but no one seems to have done that yet.

edit - based upon SI's statement regarding their camera, perhaps the single chip design is better for cinema lenses? I'm sure there are adapter mounts available.
 
vanvideo said:
But look at the videos I included above. How does it look to you? The shooter said he didn't notice any issues with a single CMOS chip. The videos look fine to me. Perhaps a lab test will bring out any aberrations, but no one seems to have done that yet.
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I don't think you can judge too much on web footage. But, I think you're right that it'll look fine - in fact I think a fairly large part of this is theoretical, and in real world conditions and TV viewing it's not a big deal. I've shot tons of stuff with long stills lenses on 2/3" chip cameras like Varicam and HDW700 and it all looked good to me - you certainly wouldn't look at it and say, blimey that was obviously shot with a stills lens.
Steve
 
vanvideo said:
But look at the videos I included above. How does it look to you? The shooter said he didn't notice any issues with a single CMOS chip. The videos look fine to me. Perhaps a lab test will bring out any aberrations, but no one seems to have done that yet.
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I'm now at a computer where I can see them properly, and firstly I really agree with steve when he says you can't judge too much on web footage - you also can't tell whether any faults spotted are simply down to a lens (it would look the same on a 2/3" camera) or a mismatch due the single chip.

That said, then I can see chromatic aberration on some shots which is more than I'd expect, and mostly on vertical edges towards the edge of frame. It seems worse on the right side of frame than the left, for some reason? A good example is on the first video at about 30secs in - the railings on the right side of frame look to have relatively bad red-green fringing?

Main thing which strikes me is that the interviews look pretty soft overall, and "muddy" appearances to such as skin tones - look at the shot at 3min 15sec for example. The lighting (or lack of it) isn't helping and I'm wondering if it might be as simple as very shallow depth of field and just being out of focus? Such as the badges on the shirt seem a bit sharper, so I'm inclined to think the focus plane is just too far back?

Final point is that it looks to me as if three cameras were used: one for the interviews, one for general filming and one for the in-car shots. I'm quite interested to know what the in-car stuff was shot with as it looks to be the sharpest of the three, in spite of looking like a wideish lens was used with some barrel distortion. It also seems to be handling the highlight contrast best of all - well exposed in the car, but still showing detail through the windows.

Just compare the in-car shot of the drivers at 1min 15secs with the interview at 1min 31secs - the guy being interviewed is the same as the one in the passenger seat in the earlier shot. Yet the in-car shots look better than the standup interview! Hmmm.
 
I don't find that many chromatic aberrations, not more than any other camera. I guess if you look hard enough, you can spot what you like.
The interviews were shot with an AF100, the b-roll with the HPX-600. I don't know what was used for the POV shots.
 
vanvideo said:
I don't find that many chromatic aberrations, not more than any other camera. I guess if you look hard enough, you can spot what you like.
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Well, I did start off by saying ".....and firstly I really agree with steve when he says you can't judge too much on web footage - ......" - apart from compression degradations, you don't know what angle of view, aperture etc anything was shot at, let alone whether the lens would have had the same aberrations on a 3 chip camera.

But to see the chromatic aberration at 30 secs in, you don't need to look at all hard - I'd disagree that it's only what you'd expect for a camera in the HPX600 price bracket. Yes, it may be the worst example, but (looking a bit harder) there are others - such as the moving shot of buildings at about 15 secs. (Again on the right hand side.) I wonder if it's more visible there because the lens was at a wider angle than for most of the filming? But that's the problem with trying to make a judgement on this sort of footage. Were these shots even taken with a HPX600? All I would say is that this footage doesn't rule out any problem - there certainly are CA issues, whether the single chip nature of the HPX600 is contributing or not remains to be seen.
The interviews were shot with an AF100, the b-roll with the HPX-600. I don't know what was used for the POV shots.
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In which case, this film is certainly not a good advert for the AF100, and whilst that hasn't got the best of reputations for being the sharpest of HD cameras, I'd expect a lot better than is seen here.

Watching it again, I'm wondering if it may largely be down to a less experienced operator doing the interviews versus the main camerawork?

Steve - if that is a GoPro, then this IS a good advert for that! But except from some very obvious rolling shutter artifacts (though less than may be expected in the conditions!) it seems at least as good technically as the main camera, and way better than the interview quality, so I'd be inclined to think something much better than a GoPro?
 
No, Dave, the shooter has a lot of experience, with good clients. it's pretty low for you to accuse him of such.
And your anti-Panasonic bigotry is really getting old.
 
vanvideo said:
No, Dave, the shooter has a lot of experience, with good clients. it's pretty low for you to accuse him of such.
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Just what is the "such" I am supposed to have accused the main shooter of? For the record, I think most of it is pretty well shot, well put together, and the overall effect is good - but the interviews don't look as sharp as the rest. Or do you disagree with that - don't you think the interviews look soft compared to all the other footage?

So why? Two most obvious reasons are either a much lower quality camera, or using a second operator of less experience to do the second camera. Or am I missing a third explanation?

The only negative thing I've said about the main footage is pointing out what I consider to be very noticeable chromatic aberration on at least one shot - the fencing at 30secs in on the first video you refer to. That's hardly the fault of the guy shooting it, and I'm not "accusing" him of causing it! Or do you disagree about the chromatic aberration at that point?
And your anti-Panasonic bigotry is really getting old.
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I can't really see how you can say that. I've said that some in-car footage seems better than an interview, and have given references to where I find that the case and why. I was actually supposing that the most likely in-car camera was something like a GH2. The quality looks too good for a GoPro or similar (and I'd expect a GoPro to give a short shutter effect), but it seems highly likely it was a fairly small camera with a fairly wide angle lens. So my money would be on something like a GH2. That would make sense in terms of trying to match the main cameras, would be a reasonable size for car mounting, and not too expensive if things went wrong!

Now all I've really said is that "shot A looks better than shot B". Even if my inference was "so therefore camera A is much better than camera B", then I'd only be saying that one Panasonic camera was better than another, so an accusation of "anti-Panasonic bigotry" seems rather wild? It would only be saying that one Panasonic camera looked better than another.

In fact, that's not at all what I have said. I actually think the GH2 and AF100 are pretty close technically - they're supposed to share the same sensor. Hence the most logical explanation is down to the operation - the background looks sharper than the subject. Or do you just simply disagree with what I'm saying about the comparison between the shots at 1min 15 sec and 1min 32 secs?
 
vanvideo said:
And your anti-Panasonic bigotry is really getting old.
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I don't think there's ever any need for personal insults. If you think someone has a bias towards or against something you just need to point it out and back up your case with facts. I don't know if harddrive is anti-Panasonic, but even he is that's not the point. If someone disagrees they can say so, if there are factual inaccuracies they can point them out and show evidence to back it up.
On the GoPro side, it was really tongue-in-cheek, but I must say that when I've seen shots in programmes I have worked on that have used GoPros I've always been amazed at how good they look - particularly the sharpness. I thought they were just silly little toys (they certainly look like it!) but they're actually a really useful tool.
Steve

Steve
 
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