25p vs 50i ( progressive vs interlaced )

[Mark Dobson]

So this is a bit of an old chestnut and obviously a subjective issue.

I watched the trailer for Philip Johnson's new C300 primer and was struck by a statement he made advising against recording in progressive mode.

' Every so often I get a phone call from somebody starting down the HD route and the first questions what do I use? Is it 50i, 50p, 24, 25, you know, basically as far as I'm concerned you stay away from 24 or 25p unless you are working with a director who is looking for that particular look '

Since I've been working with DSLR's and more recently with full HD cameras such as the XF305 and very recently the C300 I've always recorded, edited, transcoded and uploaded in progressive mode.

The reason for this is that my work is predominantly delivered for viewing on computer and HD LCD screens which have progressive displays.

Were one to record interlaced, the finished piece would need to be de-interlaced prior to delivery or upload to sites such as Vimeo.

So all my filming is done at either 1080 or 720, with a frame rate of 25p.

Is it all about aesthetics? The look? Does one method produce higher quality frames?

[Peter Manojlovic]

Originally Posted by Mark Dobson

I watched the trailer for Philip Johnson's new C300 primer and was struck by a statement he made advising against recording in progressive mode.

I'm not sure under what context he meant with that statement, but it's not correct..That's a face value assessment at my end.

Otherwise, stay progressive all the way.
Sporting events, or broadcasting will benefit from interlaced. But that's about it.

Downrezzing, uploading for web, and viewing on monitors is all progressive by nature.

[David Heath]

I suspect what he is referring to is the rendition of motion, and 24/25p can be very uncomfortable if you try to (say) pan too quickly. (It "stutters".)

But interlace at 50 fields per second and 50p give similar motion rendition, so you can still be "progressive" AND have smooth motion - it's just that with most cameras it's only at 720, 720p/50.

I can't see any reason to shoot 720p at 25 fps. If you want 25fps, go for 1080p/25. If 720 is adequate resolution, why not go for 720p/50?

[Alister Chapman]

Normally for the same frame size, progressive will be have higher spacial resolution than interlace. To prevent aliasing the fields are created by using pairs of lines, so the upper field is created from lines 1+2, 3+4, 5+6 etc then the lower field uses 2+3, 4+5, 6+7 and so on. This line blending reduces the resolution slightly.

The only things I shoot in interlace are the air shows I shoot for an external client. Everything else I have done in the past 4 years has been progressive. Progressive is so much easier to work with in these days of LCD displays. Unless you have a proper external CRT monitor in the edit suite then, you'll never know if your field order is correct or not. How many people have HD CRT's?

[Steve Game]

Originally Posted by Alister Chapman

Unless you have a proper external CRT monitor in the edit suite then, you'll never know if your field order is correct or not. How many people have HD CRT's?

If nobody is going to watch on a CRT monitor, then does it matter?

[Nigel Barker]

Originally Posted by Mark Dobson

I watched the trailer for Philip Johnson's new C300 primer and was struck by a statement he made advising against recording in progressive mode.

' Every so often I get a phone call from somebody starting down the HD route and the first questions what do I use? Is it 50i, 50p, 24, 25, you know, basically as far as I'm concerned you stay away from 24 or 25p unless you are working with a director who is looking for that particular look '

I have seen similar statements from Philip before & my take on it is that he is an old school TV camera operator who will always think that 50i is correct as that is what he has shot & been viewing for the past 20+ years. If you read his blog you will find that he also has a deep & abiding loathing of DSLRs for video & knocks them at every opportunity.

[Robert Sanders]

Progressive. Progressive, progressive, progressive. This is the year 2012 after all.

[/sarcasm]

[Jon Fairhurst]

A camera op might like interlace, but no one who does effects and compositing in post ever will! :)

[Alister Chapman]

Originally Posted by Steve Game

If nobody is going to watch on a CRT monitor, then does it matter?

It matters because if you do something in interlace with the incorrect field order, if you supply it to a broadcaster and it's wrong it will come back at you pretty quickly. There are still an awful lot of CRT TV's still in use. Perhaps if you do a corporate DVD some of the clients may still be using a CRT.

I don't really understand why anyone would choose to shoot interlace unless it involves some very fast action these days.

[Brett Sherman]

Even if it is fast action, you'd be better off shooting in 1080 50/60P with a different camera. Or even 720 50/60P with the C300. Interlaced introduces all kinds of problems and once you go to interlaced you can never do anything else with it without losing vertical resolution. 50/60P allows you the most flexibility.

[Claire Staniford]

I shot my first film on my C300 at Gatwick Airport in interlace, it looks awful on a monitor with the fields clearly visible, never again.

Progressive every time.

Hope you're enjoying the camera Mark.

[Mark Dobson]

Yes Claire - I'm delighted with the camera.

I'm in Andalucia for a week and decided to bring the camera with me. It's really easy to work with the bright light here through juggling ND, aperture and ISO.

I'm still needing to look at the camera body to make changes but think that after a few more days I will be able to find things whilst keeping my eye on the viewfinder.