View Full Version : 25F - stairs in thin objects


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Raymond Toussaint
May 4th, 2008, 03:00 PM
Shooting in 25f/25 shutter.
Would there be a cure for this?
Many thanks.

Pavel

If possible Pavel, try to shoot with shutter 50 not 25, only in static low light situations you shoot in 25 shutter. Or maybe you had a good reason to do so.
Generally shoot shutter 50, if there is to much light: add an extra ND.

btw: the mentioned detail settings-->

Sharpness: 0
H DTL FREQ: MIDDLE
DTL HV: 0

are the mainstream settings, I played with them, changed and tested them, and easely could see the difference in the "jaggie" forming. I am sure you can see that too. But, you have to adept to the shooting situation, like high contrast, diagonal lines etc.
Maybe a preset for those situations? Anyhow, if you go to SD after the edit you wan' t notice the jaggies too much.

Pavel Tomanec
May 4th, 2008, 03:56 PM
Thank you. I shall rest in peace today.

All very good points. Perhaps I could render the whole clip in HDV and import to After Effects and apply the vertical blur to the whole thing, and then down sample to any other resolution. (While writing this I feel it might not the best idea. :) How about FCP 6? Friend of mine has Sapphire plug-ins they might have some remedy. Philip, if you get a chance (and time) could you please elaborate of the procedure in AE? I am new to AE. Many thanks.

Raymond, the reason for shutter 25 - I shot documentary in India for my Uni course and was under impression that slower speed will reward me with less TV look. Was I under right impression?

Add yes, I should really create presets for specific shooting situations. Good idea!

BTW I used a preset from this site - TERRA1 consistently throughout the photography.

I love the picture just this was quite unexpected shock.

Regards,
P

Pavel Tomanec
May 18th, 2008, 03:28 AM
Hello,

Just a question, would this 'stairs' and jaggies be solved when the footage is recorded on the FireStore hard-drive unit? (I imagine to record on the tape as a backup at the same time)

If yes, I am seriously considering to get one.

Thank you for your input.

Regards,
Pavel

Richard Hunter
May 18th, 2008, 04:23 AM
Hello,

Just a though, would this 'stair' thing be solved when recording on the FireStore hard-drive unit? (I imagine to record on the tape as a backup at the same time)

If yes, I am seriously considering to get one.

Thank you for your input.

Regards,
Pavel

Hi Pavel. The tape and the hard disk record exactly the same video data, so it shouldn't make any difference.

Richard

Luc De Wandel
May 21st, 2008, 06:13 AM
Besides the 'stairs-effect' I also get a flickering effect in straight horizontal lines at 25 f. At 50i this effect is not present, or much less at least. So I shoot in 5Oi mainly.

Seun Osewa
May 21st, 2008, 07:06 AM
Why shoot progressive with interlaced ccds? You lose temporal resolution without gaining any image sharpness; it really is a big mistake. Interlaced is better than fake progressive in almost all respects.

Daniel Browning
May 21st, 2008, 09:07 AM
Why shoot progressive with interlaced ccds? You lose temporal resolution without gaining any image sharpness; it really is a big mistake. Interlaced is better than fake progressive in almost all respects.

Because interlaced video has lower resolution and worse artifacts when shown on a progressive display.

The fact is that a large and growing portion of the audience will see the video on their progressive display. Last year, just LCD television sales alone outstripped all interlaced TVs, not counting the myriad of other video display devices.

Many distribution formats only support 30p/24p, such as most Internet options, which negates the temporal resolution "advantage" of interlaced, assuming you even like the look in the first place.

Even fewer distribution formats support 60p, which prevents you from doing a high-quality deinterlace in post-production because it would, again, negate the temporal resolution.

If their display can deinterlace properly, at least they wont get the nasty flickering that interlaced TVs have, but they'll still have combing, loss of resolution, and probably more defects depending on the quality of the display's deinterlacer.

Things get even more ugly if you're extracting 24p in post-production, the motion is different from true 24p and suffers problems that 30p doesn't have. (PAL excepted.)

Finally, progressive video will look equally good on interlaced and progressive displays. So aside from temporal resolution and the artifacts discussed here, it has every advantage over interlaced video.

Tom Roper
May 21st, 2008, 11:49 AM
Because interlaced video has lower resolution and worse artifacts when shown on a progressive display.

The fact is that a large and growing portion of the audience will see the video on their progressive display. Last year, just LCD television sales alone outstripped all interlaced TVs, not counting the myriad of other video display devices.

Many distribution formats only support 30p/24p, such as most Internet options, which negates the temporal resolution "advantage" of interlaced, assuming you even like the look in the first place.

Even fewer distribution formats support 60p, which prevents you from doing a high-quality deinterlace in post-production because it would, again, negate the temporal resolution.

If their display can deinterlace properly, at least they wont get the nasty flickering that interlaced TVs have, but they'll still have combing, loss of resolution, and probably more defects depending on the quality of the display's deinterlacer.

Things get even more ugly if you're extracting 24p in post-production, the motion is different from true 24p and suffers problems that 30p doesn't have. (PAL excepted.)

Finally, progressive video will look equally good on interlaced and progressive displays. So aside from temporal resolution and the artifacts discussed here, it has every advantage over interlaced video.


I don't agree. Not for the XH-A1. 24F loses vertical resolution due to it being produced from native interlaced chips. You're point would be better made toward the Sony EX1 which gives its highest resolution in 24/25p.

And progressive displays will eventually need to properly deinterlace anyway, because 1080 interlace will remain a broadcast standard for some time, which looks fantastic on tv sets that can properly handle it. For those monitors that can't properly deinterlace, why would I want to be targeting to the lowest common denominator, when 1080i60 looks stunningly great on sets that can do it right?

What we should be insisting on are progressive displays that also properly deinterlace and reverse pulldown 1080i until the day when 1080p60 becomes a broadcast standard, which today it is not.

Daniel Browning
May 21st, 2008, 12:46 PM
I don't agree. Not for the XH-A1. 24F loses vertical resolution due to it being produced from native interlaced chips.

The Canons lose 15% resolution, sure, but progressive television deinterlacers lose far more than that, usually over 30%. The ones that don't blend away that much detail are leaving in combing, flickering, and other interlaced artifacts.

If a television display had motion-compensated deinterlacers, it would only soften the moving part of the image by 30+%, and the static portions of the image would be full resolution. But televisions don't have one because mo-comp is still far too slow.

Tom Roper
May 21st, 2008, 01:43 PM
The Canons lose 15% resolution, sure, but progressive television deinterlacers lose far more than that, usually over 30%. The ones that don't blend away that much detail are leaving in combing, flickering, and other interlaced artifacts.

If a television display had motion-compensated deinterlacers, it would only soften the moving part of the image by 30+%, and the static portions of the image would be full resolution. But televisions don't have one because mo-comp is still far too slow.

I disagree. You're lumping the progressive monitors with known poor deinterlacers to the ones that pass full bandwidth. See link below to Gery Merson's testing article:

Are You Getting All the the HDTV Resolution You Expected? Round 3 (http://www.hometheatermag.com/hookmeup/1107hook2/index.html)

When viewing 24F or 60i on a Pioneer Kuro or Elite Pro FHD1, the 60i from the Canon A1 is sharper and more artifact free as well, whether static or in motion, than the 24F which has the stairstepping jaggie due to the inherent loss of vertical resolution on the A1, which was the subject that fostered this thread.

Daniel Browning
May 21st, 2008, 02:01 PM
I disagree. You're lumping the progressive monitors with known poor deinterlacers to the ones that pass full bandwidth. See link below to Gery Merson's testing article:

Are You Getting All the the HDTV Resolution You Expected? Round 3 (http://www.hometheatermag.com/hookmeup/1107hook2/index.html)

When viewing 24F or 60i on a Pioneer Kuro or Elite Pro FHD1, the 60i from the Canon A1 is sharper and more artifact free as well, whether static or in motion, than the 24F which has the stairstepping jaggie due to the inherent loss of vertical resolution on the A1, which was the subject that fostered this thread.

I'll read the entire link when I have time, but from a cursory glance I didn't see any mention about normal interlaced artifacts such as combing and flickering; just references to artifacts caused by incorrect pulldown detection.

I've compared my A1's 30F and 24F against 60i with a variety of deinterlace-to-60p algorithms (tdint, yadiff, a few mocomp) and in every case, the interlace artifacts are always visible in high motion scenes or the motion is blurred enough to remove the artifacts.

Finally, it should be said that these resolution and artifact issues are secondary to the desired look of the production.

Tom Roper
May 21st, 2008, 09:35 PM
Finally, it should be said that these resolution and artifact issues are secondary to the desired look of the production.

Wholeheartedly agree.

Pavel Tomanec
May 26th, 2008, 02:17 AM
Hi, I also agree. How about if your desire is to have your production artifacts free as an objective for the desired look of the piece? Basically the ideal is to achieve balance between the quality of the picture and the content.

I like canon xh a1 very much, especially the 24f/25f quality. I guess will just have to live with the occasional stairs in contrasty and fast moving situations. In my view it is ultimately about the feeling, whether the picture feel like real...

Pavel Tomanec
July 20th, 2008, 07:22 AM
Hi,

just like to report that the 'stairs' after sending the footage through Compressor (mpeg2 HDV 1080p setting) came out less visible, in some cases almost disappeared. Nice.

Pavel Tomanec
January 24th, 2009, 08:44 AM
Ok, recently I shot water fall on a bright day and then I looked at the footage. Basically the horizontal line or stair was traveling across the frame all the way through from bottom direction up. Terrifying.

Then I have noticed that using camera filters helped the images. I shot with 6x4 Low Contrast 1 and 3 strength and Diffuser number 1. The picture was clearer in a sense that it did not have the infamous stairs on it even on a bright day and with some movements in the frame. But I did not change any setting in the camera, mainly using Panavision 2 and Terra 2 present but with more sharpening added (-2 to -4).

I can't help myself but thinking and hopefully seeing too that the 25f mode appears better in FCP than 50i.

Regards,
Pavel