Does the AF-100 Line skip?

[Jan Crittenden Livingston]

Originally Posted by David Heath

The apparent contradiction is easily explained. Look at Simon Wyndhams second photograph - the one with the resolution blocks of horizontal lines. You can clearly see lines seemingly "resolved" on the 800 line resolution block. I'm sure this is what Jan is seeing.

Actually I am seeing resolution in the DSC chart and it is not aliasing. You cannot be sure about what I am seeing as you are not here in my lab looking at my setup and my DSC chart.

Thanks,

Jan

[Mestizo Devon]

Originally Posted by James Campbell

Stupid question (as I'm deciding between the EX1R and the AF100): for approximately the same price, I could buy an AF100 along with a NanoFlash unit as compared to an EX1R. Wouldn't using the NanoFlash with the AF100 and being able to record at such a high bitrate with 4:2:2 color raise the quality of the AF100 video capture above what the EX1R captures natively? (I know it's a newbie question... I'm just not sure what happens when in the capture process to capture higher resolution).

Where can you purchase an Af100 and nanoflash for less than a exlr?

[David Heath]

Originally Posted by Jan Crittenden Livingston

You cannot be sure about what I am seeing as you are not here in my lab looking at my setup and my DSC chart.

Well - can I ask how you therefore explain Simons chart that we are all able to see?

Which clearly DOES seem to show the 800 line result to be aliasing? And which seems to correlate with other results that have been seen?

Is it possible for you to post an image of a test chart (ideally a zone plate) showing exactly the results you are obtaining?

[Jan Crittenden Livingston]

Not sure what Simon posted, didn't look at it. Keep in mind that resolution is a factor of more than just the camera. You need a lens that will resolve the resolution as well. We are using a backlit DSC chart, a Zeiss 50mm Compact Prime and the AF100 set at 400 ISO.

Best,

Jan

[Simon Wyndham]

Jan, you really should look at the images I posted (and it is, if you don't mind me saying, a little curt to dismiss them out of hand and hold a discussion on the matter without even looking at them). Aliasing is visible where there is no apparent detail at all, which completely rules out the lens or focus. The lens was clearly resolving the detail, but the camera was reducing it all to aliasing.

Further, as David mentioned, others who have been performing tests have been getting similar results. I do not think there is any need to be defensive about this. Science is about actual results, not emotional disagreement. Without seeing your results, especially a zone plate which would prove what you are saying outright, we cannot take what you say as read, especially when the evidence that is on show says otherwise. Incidentally, the chart used in the shots I posted was a front lit DSC chart. Other settings are irrelevant in this case AFAIAC. If the lens was firing an even sharper image into the camera the aliasing wouldn't go away. Some reduction in aliasing might be achieved by lowering the enhancement in camera, but as you can see there is aliasing even on areas where detail has been reduced to an almost flat grey fill.

[Chris Hurd]

There has been absolutely no "emotional disagreement" anywhere in this discussion, but
it's just that type of baseless accusation that results in closed threads and locked accounts.

Don't do it again.

[David W. Jones]

So let me ask the question one more time Simon, did you shoot the chart or was it passed on to you?

Our results were as Jan had mentioned. We tested the AF100 on several charts, in several scenarios, and under varying conditions. It passed our tests with flying colors and we put in into use with our Red.

You may be into the "science" of camera specs, which is all well and good.
But we are into making money in the commercial business. And this camera paid for itself in under a week! IMHO, this camera is a no-brainer, no matter how many lines of resolution "you" are seeing on a chart.

All the Best!

Dave

[Jan Crittenden Livingston]

Hi Simon,

So which lens did you use? I think it is pretty odd as I know that my engineer , Barry Green and I all saw 800 lines. Barry Russo, said he would set it up again and do a frame grab for me, but it might take a couple of days. Settings were right out of the box without tweaking. I thik the lens might be a key influencer on this though.

Best,

Jan

[David Heath]

Originally Posted by Jan Crittenden Livingston

Not sure what Simon posted, didn't look at it.

I really think it would be a good idea if you did, Jan. The results are pretty conclusive, especially regarding the alias patterns from the circular resolution rings.

Did you read what I previously put? (Post no 50.) If not:

Originally Posted by David Heath

True (or "real") detail resolves as it should according to the original chart, aliasing shows as a false,arc whose centre appears to be somewhere other than the centre of the pattern. Simon Wyndhams first image shows the aliasing well. On the fourth ring (the 800lph ring), the circles appear to have a centre to the left of the chart - they are clearly aliases.

Originally Posted by Jan Crittenden Livingston

Keep in mind that resolution is a factor of more than just the camera. You need a lens that will resolve the resolution as well.

Again, this has been covered before. (See post 52.) A different lens will give a different mtf to the result - but will do NOTHING to affect the shape of the alias patterns, if any can be seen. Their shape is solely a function of the native camera resolution.

And as Simon says, the mere fact that alias patterns CAN be seen must indicate that it's the native camera resolution that is the weak link - NOT lens resolution.

If you dispute the results that Simon posted, if you think he has done something wrong, then please, would you like to show us what you have seen?

[EDIT - Having just seen your last answer, can I further ask if your chart had circular rings of resolution (as Simons example) or just vertical and horizontal lines? The former shows up what is true detail and what is aliasing easily, the latter doesn't do so anything like as well. If it's all you've got, try panning the camera slowly from side to side. If the 800 block lines appear to ripple in the opposite direction to the direction the block is moving, they're aliases.]

[Jan Crittenden Livingston]

Okay, So I took a look at the charts that Simon posted. And as soon as Barry pulls it together I will post our results but they do not look like Simon's results.

Best,

Jan

[David Heath]

Originally Posted by Jan Crittenden Livingston

.....as soon as Barry pulls it together I will post our results ...

Thanks Jan - I look forward to seeing them.

After the last paragraph of my last post, it occurs to me that if you only have a chart with horizontal and vertical res lines, then could you also post a couple of seconds of movement - very slowly panning across the chart? So we can be unequivocally sure whether we're seeing aliasing or real detail? Obviously, a chart with circular resolution or a zone plate would be far better.

The effect ("If the 800 block lines appear to ripple in the opposite direction to the direction the block is moving, they're aliases") is analogous to the wagon wheels on the stagecoach appearing to turn backwards. (That's also aliasing, though wrt time, not space, as in this case.)

[James Campbell]

Quote from David Jones in post #67:

"Our results were as Jan had mentioned. We tested the AF100 on several charts, in several scenarios, and under varying conditions."

David: are you also able to post your results?

[David W. Jones]

Originally Posted by James Campbell

Quote from David Jones in post #67:

"Our results were as Jan had mentioned. We tested the AF100 on several charts, in several scenarios, and under varying conditions."

David: are you also able to post your results?

We burned that footage long ago. No need to keep it around as we have put the camera into production work. We captured to SDXC card as well as SDI into a Kona card and determined that for the majority of the stuff we would shoot with the AF100, SDXC would be fine. For higher end work & keying we can use the Red. As far as footage goes, we do broadcast work which we never post on places like youtube or vimeo.

By the way... This thread has gone way off course.
Original question... Does the AF100 line skip?
Answered by Panasonic Rep... No.

All the Best!

Dave

[David Heath]

Originally Posted by David W. Jones

By the way... This thread has gone way off course.
Original question... Does the AF100 line skip?

I disagree that the thread has gone off course. It's possible to infer quite a lot from properly done test charts about how a camera is working internally, how it's reading the chip. If we accept Simons results as valid, then one thing they conclusively prove is that it is *NOT* line skipping - as I said many posts ago, see post no 40.

Line skipping would not give a symmetrical hor/vert result to zone plates or Simons chart. Of course, the obvious question then is "if not line skipping, what is it doing?"! That's the current validity to the thread.

The most likely theories I've had presented to me revolve around some form of pixel binning (which the GH2 - same sensor - certainly DOES do in some modes) - but Jan denies that. So if not that, just what is it doing?

I think the next step is to see whether any further tests show different results to Simons, or tend to substantiate what he has posted. Let's wait and see what Jan comes up with - and may I ask how Olofs tests with an AF101 and charts are going? (Post 51.) Do you have anything yet to share with us, Olof? (And do you have charts with circular resolution rings?)

[William Hohauser]

I am enjoying this discussion very much. A lot of important technical issues are being discussed here. Regardless of the resolution issues, the camera puts out a very, very impressive image.