Phantom Power, 25fps and shutter speed defaults
 

Hi

I have a new XH A1 after many faithful years of using a XL1.

I have three questions that maybe other users could help answer.

1) I have a sennheiser ME66 mini shotgun mic. It works with the phantom power switch both turned on and off. It has it's own power module and battery, and works with phantom power.

If I have the mics power module on, and phantom power on, which power source will be overruled?

2) 25fps - is there any real benefit in using this setting? What will be the differences in the footage between 25fps and 50i?

3) and finally, on my old faithful XL1, I pretty much left my shutter speed on 1/60 at all times (unless I wanted a nice shutter effect when filming waterfalls, or helicopter blades in action)

I was told 1/60 was a good default shutter speed to use, and have never really questioned this. Would people agree?

thanks for you patience (in advance)

1) Phantom overrides the battery ( as fas as I know). Phantom, being higher voltage, also gives better S/N ratio.

2) 25p takes only one exposure every 1/25:th of the second (and TV-sets show this as 2 fields 1/50 sec apart). 50i exposes every 1/50 sec and shows these as interlaced fields. 50i makes smoother motion. Use 25p if you want jerky movement or if you are transfering your video to film or make video for net only. 50i is the PAL television standard, use that untill you have a compelling reason and understanding not to. Some people swear by 25p because it behaves like film, but as 50i looks BETTER in my eyes as far as the movement is concerned, I do not understand why some like an inferior result. Why not shoot B/W, true art films were done that way. How about Chaplin-like 16fps?

3) With 50i PAL the standard shutter speed is 1/50. For fast, clear motion use faster speeds, but at the expence of strobing like effect.

I don't know this mic, but generally, phantom power is suppose to be better than battery if you have a choice. Also, when using phantom power, I've always seen it advised to take out the battery.

thanks guys, very thorough answer Petri, very interesting about 25fps. Think I will stick with 50i

50i
 

Yeah stick with 50i mate or Stef will give you the sack!

Yep--1/50 is standard for 25fps PAL countries, 1/60 for 30 fps NTSC countries. I've been shooting most everything at 24 fps and 1/48 and like the progressive look better than interlaced. Most of my stuff goes to web and/or DVD, and eliminating interlace artifacts is a good thing. Also, 24 frames in a second is less data than 30 frames in a second, which is nice when web data rate and all is an issue.

Check the microphone manual. Usually it's fine to leave the battery in.

A reason for taking out the battery is so it won't corrode and destroy the microphone.

For long-term storage, you mean. That's true of anything that uses batteries, not just microphones.

I want to clarify 25p and 50i's differences a bit.

50i (interlaced) shoots fifty fields per second (at 25 frames per second, with each field respectively making up half of a frame), basically every even line is captured, and then every odd line, in a sequence. Thusly, when there's a large amount of movement, the fields will actually show slightly different images. This technique was used to make shooting high speed material easier (such as sport) and to allow easier wireless broadcasting of televised signals (which may have been the sole reason for introduction in the first place).
Interlaced has another benefit - if you're shooting and want to use slow-motion in your clip, it can duplicate or interpolate the missing information in each field, to give you a sort of faux-50p, albeit a somewhat blurry version.
The downsides of 50i? Technically you cut your vertical resolution in half, because you're shooting two frames at once. Interlacing causes severe jagged edges on hard, sharp angled lines, and is also perceivably more blurry than other video formats.

25p (or progressive) shoots 25 frames per second. There's no loss of horizontal resolution because it isn't recording half-frames. The picture is generally clearer and doesn't suffer the jagged edges and general blurriness that interlaced video does. However, there are downsides to this format too. Slow-motion is literally just dropping the frame rate, and so it appears more jumpy - the only way to improve this is to shoot in a higher frame rate, which no low-end DV cameras support (I'll say more about this later).
Progressive is also a monster which requires *experience*. You cannot simply shoot progressive the same way you shot interlaced and expect it to look the same. Due to the *perceived* lower frame rate of progressive, pans (in particular) need to be executed according to a formula (there's a lot of information on this on the internet). You also need to be more wary of moving objects, and it pays to know at what ratio you can follow an object and at what speed to avoid stuttering in your video.
However, the result is a vastly superior picture quality that has one incredibly huge benefit over interlaced: it looks like film. You know how you'll see something on TV, some post produced show, and there's just something about the vision that looks different to live TV? That's most likely because they shot in progressive (and also because they used FFL lenses, and that's also very relevant).
Fixed Focal Length lenses shoot with a very shallow Depth of Field. In modern times, these are used to creative effect, but it is said that they were originally used in film to allow movement of the camera. When the 24 frame per second shutter was devised, it allowed more motion and a more fluid image over 16fps, but the issue was that stuttering still occurred when panning or moving too fast. The solution therefore was to use lenses that basically kept only the subject in focus (when necessary) - the blurry background is actually stuttering but its harder to perceive because its out of focus - and this can be vitally important to progressive production.

Times to use interlaced: unpredictable events (such as doco shooting unless you're very proficient with progressive), straight to TV, sports coverage
Times to use progressive: theatre, post produced content, weddings

The above quick and nasty guide is also very basic in one regard - it doesn't allow for higher progressive frame rates. When watching sports, you'll notice that they often have amazing slow-motion footage, incredibly clear and accurate. This is achieved by shooting at a high progressive frame-rate. For sports they generally use 120p (that is 120 frames per second - not sure if the PAL equivalent is 100p). Some low-end cameras can achieve this effect. Sony have been introducing HDV cameras that can shoot 3 seconds of footage at 120 interlaced frames per second (although apparently the method used for achieving this lowers the vertical AND horizontal resolutions further, and HDV 1080i is already gimped). JVC's semi-pro HD cameras since their inception have included a 50p/60p standard definition CODEC, although this is not widely supported. The newest higher end JVC HDV cameras can shoot 50p and 60p at 720HD. Sony's new EX-1 will also shoot 720p60, and Panasonic's HVX200 is well known for shooting DVCPROHD at 720p60, and as such has been a favourite for post-produced content, the fixed lens be damned.

So, in closing, Petri posed the following: 'I do not understand why some like an inferior result. Why not shoot B/W, true art films were done that way. How about Chaplin-like 16fps?'
My answer is - I too am baffled that some people prefer an inferior result - why would you shoot interlaced at all, ever? Especially if you could get access to a 50p capable camera? Superior pixel resolution, that smooth film-look effect, and highly useable stills are all benefits of progressive. All you need is a good knowledge of the format and you can shoot progressive very easily in almost any situation with a minimum of stutter. One thing that puts people off is when shooting, the images in the viewfinder look jittery and bad, but you become accustomed to the effect - and you will not notice it in the images you've shot when it comes to post production.
In England they are pushing to stop ALL interlaced broadcasts. BBC even had the gall to do a live broadcast in progressive. Many people called in to complain because they felt that it had been pre-recorded, because the footage looked as if it was post-produced, but it wasn't - and viewers could tell the difference.

My suggestion: research progressive vs interlaced yourself, and draw your own conclusions. Experiment with your own camera, find out who else is using progressive and take a look at their footage or at least see in what field/area they're using progressive as de facto standard over interlaced. In the end its a matter of knowing what is best in what place/time. Eventually, all cameras will come pre-equipped with 50/60p and this whole discussion will be a moot point.


Cheers

Justin, welcome to DVinfo. You'll notice that your post has been slightly edited to remove some harsh wording.

A quick search of DVinfo will show many similar discussions -- well trodden ground. Most of the factual information folks have written in this thread is on the mark, but when words like "inferior" creep in, the discussions usually become opinion and a matter of personal taste, not fact. After all, the preceding posts have shown that at a given price point or level of technology, both interlaced and progressive video have their uses. And a lot of us do use 'em both. Things are moving fast but currently in the sub-$10K market, we can get very nice 1080 at 24p/25p/30p and 60i, or 720p60. Yeah, I think most of us dream of shooting 4Kp120 dialed up to a razor-thin DOF with our micro-palm-sized cameras one day, but that ain't today.

To clarify a couple of points:

- Viewed at normal speed on an appropriate display, 60i and 30p have a qualitatively different look to most people, but carry essentially the same amount of resolution information. Interlaced would present "half resolution" if used for 50% slow motion. On a display system that doesn't do a decent de-interlace, you'll see the distracting "comb tooth" or "jagged edge" artifacts in areas where there is motion from field to field, whereas in static areas the resolution would not be degraded. As they say, it's all in the presentation.

- The depth of field of a lens isn't lock-step related to whether the focal length is fixed, per se. Top quality prime lenses have advantages of being of simpler design (less glass), optimized for their one focal length, and oftentimes can achieve a wider aperture than a zoom lens set to the same focal length owing to their simpler construction. But depending on the optical design involving multiple factors such as the intended sensor size and other geometries, either prime or zoom lenses can have a relatively shallow or deep depth of field. But of course, quality zoom lenses aren't half bad nowadays and have a tremendous advantage for video: their ZOOM! An opinion, but I don't think a fixed lens is the nirvana highway to awesome film-like TV productions.

Anyway, 35mm-like DOF is just one production decision a filmmaker chooses, if he or she can afford it, that may win a viewer's heart. Same deal for the super high dollar cameras used to get those great sports slo- mo you see on network TV; they are way at the high end and got the tool to do it. But sadly, not applicable to almost any of us here at this particular juncture in history. Maybe next year we can get that 4kp120!

Mark, soak up the information and opinions in this thread and the many others like it. But in the end, don't let labels or name calling of a particular format or technology sway you too much. Shoot some scenes in both 25p and 50i and see what you like for your purposes.