25p or 50i - Detail

[Pietro Jona]

Ex1/EX1 r user here.
This is not about what looks better, I always shoot 25p and I like the look of it. Never thought that it was jittery or anything, just progressive as its name says.
A colorist that is going to do the CC on some footage I'm going to shoot soon for a documentary told me that I better shoot in 50i, he will take care of deinterlacing the footage making it a "better and more detailed" 25p footage. To me this is total nonsense, i remember when deinterlacing footage from 50i only cameras was the only way to get a progressive like footage and the results where a good loss of definition.
Any thoughts?
As for detail: knowing that the footage is going to be post processed does it make sense to shoot with detail off all the time (I usually do when using cinegamma 4 in low light, otherwise in bright scenes i use CG1) and apply a sharpen effect later? Do you all shoot with detail on?

[Jack Zhang]

I also shoot primarily in 30p (NTSC version of 25p)

But I turn down the detail PP setting -5 in progressive because I always found there was always a tiny bit of oversharpening going on with Sony cams. Turning detail off just pretty much defaults.

I think the Colorist is referring to better motion reproduction. You can reproduce de-interlaced motion in 30p and 25p by choosing a shutter angle of 180 degrees. If you're using shutter speed, 1/60 for NTSC and 1/50 for PAL.

Do keep in mind that you lose sensitivity by doing this in progressive. By shooting in 50i or 60i, you retain sensitivity and de-interlaced motion would equal a shutter angle of 180 degrees.

I don't doubt 50i can be filmized and look good, Doctor Who in the middle of the Tennant days was all filmized 50i to 25p.

[Pietro Jona]

Thanks. As I wrote, the colorist didn't talk about motion reproduction and I actually always shoot in 25p.

[Robin Probyn]

Jack can you explain

You can reproduce de-interlaced motion in 30p and 25p by choosing a shutter angle of 180 degrees


Its standard practice to use 180 shutter in 24/25/30p to cut down motion blur .. but I dont understand the first bit..?

[Alister Chapman]

Originally Posted by Pietro Jona

A colorist that is going to do the CC on some footage I'm going to shoot soon for a documentary told me that I better shoot in 50i, he will take care of deinterlacing the footage making it a "better and more detailed" 25p footage.

That is utter nonsense and impossible. When a camera creates an interlaced field it does so by combining alternate line pairs, so for example with field one the camera blends line 1+2 then 3+4, 5+6 etc and for the second field it does the same but one line later so lines 2+3 then 4+5, 6+7 etc. This line blending is done to prevent the lines in the fields from flickering or twittering. As a result of this line blending the resolution in interlaced is reduced, so most cameras including the EX cameras have reduced resolution when shooting interlace than progressive.

In addition with a 4:2:0 camera the way the colour sampling is done combined with the field structure means that in interlace there is an even greater reduction of the chroma resolution as the sampling becomes asymmetric and it is not uncommon to see this as chroma banding around very fine highly saturated colours. In progressive 4:2:0 the chroma sampling is symmetrical and this results in better colour rendition.

In almost every respect a progressive image is superior to an interlaced one, the only issue is the reduced frame/field rate between 50i/25p. De-interlacing an image with motion will add extra artefacts. There is no way a de-interlaced image will look better than an progressive originated image shot correctly with an EX.

Shooting with detail off and sharpening in post is a viable workflow and one that I do use from time to time with good results. However I tend to shoot with detail on but at a reduced level (-12) for most things.

[Pietro Jona]

Thanks Alister,

it's what I tried to tell the guy. I'll shoot 25 as usual.
As for detail, I think I'm going to keep it off all the time. I usually shoot with Cinema matrix +25, CG1 in bright light and CG4 with +10-20 black gamma in low light. Black is -4 or whatever takes to bring blacks to 0.
Thanks again

pietro

[Robert Bale]

Originally Posted by Alister Chapman

That is utter nonsense and impossible. When a camera creates an interlaced field it does so by combining alternate line pairs, so for example with field one the camera blends line 1+2 then 3+4, 5+6 etc and for the second field it does the same but one line later so lines 2+3 then 4+5, 6+7 etc. This line blending is done to prevent the lines in the fields from flickering or twittering. As a result of this line blending the resolution in interlaced is reduced, so most cameras including the EX cameras have reduced resolution when shooting interlace than progressive.

In addition with a 4:2:0 camera the way the colour sampling is done combined with the field structure means that in interlace there is an even greater reduction of the chroma resolution as the sampling becomes asymmetric and it is not uncommon to see this as chroma banding around very fine highly saturated colours. In progressive 4:2:0 the chroma sampling is symmetrical and this results in better colour rendition.

In almost every respect a progressive image is superior to an interlaced one, the only issue is the reduced frame/field rate between 50i/25p. De-interlacing an image with motion will add extra artefacts. There is no way a de-interlaced image will look better than an progressive originated image shot correctly with an EX.

Shooting with detail off and sharpening in post is a viable workflow and one that I do use from time to time with good results. However I tend to shoot with detail on but at a reduced level (-12) for most things.

Hi Alister, I have a question, as I am in pal land, and have a client in the USA, need to deliver in 30p, so do you know of a good converter 50p to 30p, ? Or can I shoot 25p and go up to 30p ? I Have to shoot at 50p because of the lighting over here, I found if I shot at 30p I got very bad pulsing or filckering for the room lights.

[Alister Chapman]

Just shoot at 30p with a 1/50 or 1/100th shutter and your lighting problems should go away.

It's quite hard to convert from 25p to 30p well. I do it with Compressor on my mac when I have to and use the advance frame interpolation settings to get the best results.

At least it's not quite as hard as trying to convert 25i to 30i.