Does the AF-100 Line skip?

[Olof Ekbergh]

Originally Posted by Godfrey Kirby

Sorry, I'm a bit lost! Which micro 4:3 (m4/3) focal length should one have to achieve a wide angle view on a GH2, in video mode? By 'wide angle' I mean an angle of acceptance similar to that of a 35mm or 28mm lens on full frame stills 35mm.
In fact I'm so confused that maybe this post should have gone in the GH2 thread; except I want to use the GH2 I just ordered, alongside the AF 100/1 that I have just ordered. (Rush of blood to head.)

And is my old Nikkor 50mm only good for C.U.s of the Sea of Tranquillity? (On the Moon.)

To compare to full frame is a 2X multiplier.

So:
14mm MFT= 28mm 35FF
17mm MFT= 34mm 35FF
50mm MFT=100mm 35FF

This is comparing angle of view, not DOF. F-stop stays the same.

[Godfrey Kirby]

SIDEBAR. Since a Four Thirds sensor already produces a 2X field of view as compared to full frame 35mm, this means that in ETC video mode the focal length marked on the lens is actually 5.2X what it would be in full-frame 35mm terms. So the long end of the new 100-300mm zoom is equivalent to 1,560mm in Extra Tele Conv video mode. Wildlife cinematography anyone?

This is from the link on the post by David Mark Williams, who happens to live in the same county as me, maybe I should walk round to his place and ask him!

Regards - Godfrey

[Mark David Williams]

Originally Posted by Godfrey Kirby

SIDEBAR. Since a Four Thirds sensor already produces a 2X field of view as compared to full frame 35mm, this means that in ETC video mode the focal length marked on the lens is actually 5.2X what it would be in full-frame 35mm terms. So the long end of the new 100-300mm zoom is equivalent to 1,560mm in Extra Tele Conv video mode. Wildlife cinematography anyone?

This is from the link on the post by David Mark Williams, who happens to live in the same county as me, maybe I should walk round to his place and ask him!

Regards - Godfrey

Hi Godfrey I'm a bit confused by your post as it wasn't about the crop factor or what the ETC mode does. So to clarify my position.. I'm interested in buying the camera. My previous post was trying to figure out what is being said here about line skipping and was addressed to David to try an offer an explanation as to why the camera may not skip lines. Jan gave a definitive answer that the AF100 doesn't line skip and Davids post that for the cost and other barriers it likely does.

So two opposite answers raise more questions. I searched the net trying to find more info and the ETC video mode link explains there is no line skipping pixel binning etc in this mode so I may not know what I'm talking about in the previous post but hope David or Jan may put me straight on exactly how or why the AF100 does or doesnt line skip.

[David Heath]

Originally Posted by Mark David Williams

Panasonic GH2 1:1 Mode Revealed

ETC Which shows you don't need to line skip?

No - this mode only uses the centre part of the sensor, the middle 2 megapixels of the 18 total. It's a perfectly valid thing to do, but (as the article makes clear) it results in a "zooming in" compared to a standard still. The article says you get a "free teleconvertor", which is great if you want one - but a dead loss if you want a wide angle lens!

It would also negate the whole reason behind such a camera as the AF101 (you want a large sensor, that's what gives the shallow dof). In this case, you'd be building the 4/3 sensor in - then only using the central part! Far better to just use something like a 1/2" sensor and use all of it.

It's pretty easy to tell this from measurements of angle of view at differing focal lengths - the AF101 is using the whole width of the chip, which translates to 12.4 million photosites available.

Does that help?

As far as "line skipping" itself goes, line skipping is a special case of pixel skipping - a camera can pixel skip, but not line skip. There's an (incorrect) widely held belief that pixel skipping necessarily means "nasties" such as moire, aliasing etc. The belief therefore goes that if no moire/aliasing - therefore it proves no line (pixel) skipping. That's completely untrue.

What IS true is that pixel skipping on a high photosite sensor WILL give aliasing IF - NO - OLPF - IS - USED. Use an OLPF, and the moire/aliasing etc problem is largely solved, even if some form of pixel skipping is still used in the chip readout. Pixel skipping shouldn't necessarily be thought of as a "bad thing" in itself - only when the OLPF isn't used.

The "good thing" about pixel skipping is that it enables decent video to be obtained from what are basically still camera sensors, at a sensible price, power consumption, etc.

You may then be wondering why, if they are such a good thing, why not fit OLPFs to DSLR sensors? Answer is easy - they greatly improve the video, but restrict the resolution of stills to only HD resolution (2 megapixel). Great in the AF101 - useless in a DSLR! :-)

[Godfrey Kirby]

Thanks Mark (Sorry I got your name wrong! - said I was confused) & David - So, the ETC (teleconvertor) is an additional feature of the camera, not something that happens when you switch it into Video Mode. For a nasty moment there I thought I was going to have to stand in Essex in order to do a 'head and shoulders' framing in Hertfordshire......

Not that I have got anything against Essex.... except the usual...

[Mark David Williams]

Hi David okay its just the article mentions no line skipping used as part of the ETC process and wondered if this might have been a way to avoid it in other areas of the Cameras capture process.. I can see I'm confusing two separate issues.

I really don't know any more now than I did when I first started only that the camera may or may not line skip and my personal opinion would be if it line skips DON'T BUY because of the fear of problems in post with colour correction picture quality and green screen. Obviously if line skipping was an option Jim Jannard would be using it in his cameras.

My thoughts being a bit cynical are just my personal opinion based on the ruthlessnes of much of big business..
My suspicion was the Sony EX1 was an answer to Reds foray. Jim was an advocate for the ripped off consumer while major brands every year bought out slight improvements so everyone went out and bought a new model. But although Red has certainly stirred up the markets is now establishing itself as no longer a threat to the consumer market IE Price and the Scarlet is only going to be two thirds.

The AF101 potentially takes a lot of those consumers who hoped scarlet would be what AF100 appears to be. When in fact the AF100 won't be accepted as professional or useful in a professional capacity due to line skipping. So keeping the status quo of consumer and professional market apart.

At this moment in time I think it may be prudent to watch. The EX1/3 May turn out to be a very good and lasting buy even if using a Letus adapter.

[Nigel Barker]

Originally Posted by Mark David Williams

I really don't know any more now than I did when I first started only that the camera may or may not line skip and my personal opinion would be if it line skips DON'T BUY because of the fear of problems in post with colour correction picture quality and green screen.

You have had the categoric assurance that this camera does not line skip from the Panasonic US Product Manager so I am not sure why you persist in this confusion.

[Brian Drysdale]

I'm not sure why the EX1/3 series should be compared to RED, they're very different cameras and extremely successful. Most productions actaully don't need a larger sensor, sure there's a lot of talk on forums, but the 2/3" and smaller are out in much larger numbers.

Given that DSLRs are being accepted on on professional productions in spite of a number of issues, I can't see why the AF100 shouldn't be. It remains to be seen if HD broadcasters will accept it recording onto a Nanoflash etc, but that just one professional sector and the chances are pretty good that they will accept it for quite a few types of production. Until the camera gets tested they can't make a judgement.

[Mark David Williams]

Originally Posted by Brian Drysdale

I'm not sure why the EX1/3 series should be compared to RED, they're very different cameras and extremely successful. Most productions actaully don't need a larger sensor, sure there's a lot of talk on forums, but the 2/3" and smaller are out in much larger numbers.

Given that DSLRs are being accepted on on professional productions in spite of a number of issues, I can't see why the AF100 shouldn't be. It remains to be seen if HD broadcasters will accept it recording onto a Nanoflash etc, but that just one professional sector and the chances are pretty good that they will accept it for quite a few types of production. Until the camera gets tested they can't make a judgement.

I agree Brian but I suspect many will buy the AF100 Thinking it is professional when it may not be which is what I'm trying to ascertain.

Originally Posted by Nigel Barker

You have had the categoric assurance that this camera does not line skip from the Panasonic US Product Manager so I am not sure why you persist in this confusion.

Actually its not me that is persisting in the confusion. Maybe you should read David Heaths post who clearly shows the Camera is likely to line skip. His explanation sounds right and technical. Are you saying that David has got it wrong and Jan is right and if so can you present a technical reason as to how the camera does away with Line skipping? Clearly this is something Red would love to be able to do Are you saying the Panasonic has beaten red to the post with this?.

[Nigel Barker]

No disrespect to David but I think to prefer the speculations of some contributor on an Internet forum over an assurance from a representative of the manufacturer is an odd choice. I don't need to give a technical reason as I am quite prepared to take on trust that the engineers at Panasonic who really know about this stuff (unlike us forum contributors) did whatever was necessary to accomplish their magic.

[Chris Hurd]

I can't speak for other internet message boards (thankfully), but as
far as DV Info Net is concerned, the input from the product manager
usually trumps everybody else.

[Mark David Williams]

Originally Posted by Nigel Barker

No disrespect to David but I think to prefer the speculations of some contributor on an Internet forum over an assurance from a representative of the manufacturer is an odd choice. I don't need to give a technical reason as I am quite prepared to take on trust that the engineers at Panasonic who really know about this stuff (unlike us forum contributors) did whatever was necessary to accomplish their magic.

I would like to hear a further technical explanation how this problem is avoided after all there may be another way similar to line skipping and if so would like to here the pros and cons. Maybe the issue is fully resolved and if so how? I'm not asking for full details trade secrets etc Just an acknowledgement there was a problem that was resolved and a brief summing up of how and why.

This way I and others will be able to make a determination on whether this meets our needs

Originally Posted by Chris Hurd

I can't speak for other internet message boards (thankfully), but as
far as DV Info Net is concerned, the input from the product manager
usually trumps everybody else.

Chris I agree that Jan is right I hope you don't mind though if I pursue more information re this.

[Olof Ekbergh]

Mark, I think the proof is in the footage. Soon there will be all kinds of footage available. I should have my camera soon. And I will be doing a bunch of comparisons to other cameras.

From what I have seen so far Pany has done an excellent job of downsampling without any hint of stair stepping or moire. I did see and handle the AF100 in Boston a while ago and I saw the SDI out on a large screen from 6' away, even in low light the picture was very good. Jan explained that there was a lot of proprietary "magic" in how the downsampling is done. That may be as technical an explanation as we will get in the near future.

If you have any doubts about ordering this camera I would suggest you rent one and do your own testing, soon there will be lots of them available, I am sure.

I think one of the huge things to remember about this camera is that it is not a Varicam, F3 or F35, and it is not trying to be. It is a $4,800.00 camera (v/o lens), and for that price it is quite remarkable. It is 8 bit with 422 SDI out. The native codec looks good for a lot of purposes as well. It certainly rivals the Canon DSLR and EXcam 35mb codecs.

It is the first of this kind of camera and I for one really like what I have seen so far.

Merry X-mas to all, and congratulations to Jan and the whole Pany team.

[Mark David Williams]

Olof

I don't know as I would call it remarkable I would say progressive but it is a camera without a lens. What I would call remarkable is the fact you can buy a new car for not much more.

We have a deal here.. Consumers buy. Manufacturers make products to make a profit and not because they are doing us a favour they are after all businesses.

Manufacturers DO not do consumers favours they SELL.

Marketing hype advertising and commercialism is I'm sure a concept we are all familiar with all I'm trying to do is get an answer to what I am purchasing. If some are happy with the explanation of magic and secrets fine that's consumer choice too. I though prefer to understand what I may be buying into.

[Brian Drysdale]

Panasonic have traditionally been rather slow in disclosing certain information, but it does come out in the end.

In the short term, for a user, the important thing is if it does what they need and, in reality, the only way to find out is to test it, regardless of the methodology or claims used by a camera manufacturer.

In the past, tests have also revealed the processes used.