24p questions

[Nathan Gifford]

If your desire is to prep your video for film try checking into these articles on the Watchdog site:

DV to 35mm Technology Guide, Part One
DV to 35mm Technology Guide, Part Two
DV to 35mm Technology Guide, Part Three

[James David Walley]

I notice that the specs for the DVX100 list a minimum lux of 3 at f1.6 with 18 dB gain. However, I also understand that you cannot use the higher gain unless you're in 60i mode. Does anyone know what the minimum lux would be if you're shooting in a 24p mode where gain boost is disabled? Thanks in advance.

[Frank Granovski]

Minimum LUX is a subjective call. If you disable the gain, I would guess you'll need at least 100 LUX for reasonable footage. If you don't have the gain enabled, the cam will probably have black footage (in really low light)---in other words, it won't capture. Perhaps experiment and let use know your findings.

[James David Walley]

I can't "experiment" because I don't have the camera yet, and this information will help me decide whether or not I should buy. From whay you're saying, if you shoot 24p, you need 100 lux to virtually anything? That seems very high, indeed.

[Stephen van Vuuren]

That's way too high. Look at some very low light screen grabs done in 24p (I posted some here several days ago).

While you may not use the DVX100 as night-time infrared spy cam, it shoot beautiful images in low-light (i.e. completely dark room with single candle).

[Ron Little]

OK guys here is my dilemma,

I have been asked to shoot a made for video feature length horror flick.

The star of the show is an accomplished actor with stage and film experience. This will be his first movie that he is producing.

The budget is small, fifty thousand. I have decided to use the DVX100 to shoot this {soon to be on the back of the discount rack} classic.

My original thought was to shoot it in 60i because it is intended for the video store.

But I started thinking, what if this turns out to be something that could go to film?

Should I shoot it in 24p just in case?

[Glen Elliott]

Regardless of it's target why not shoot it in 24p. It'll at least alter the look of it so it's not the typical home-movie 60i look. Sure you wont have gain or manual focus but with a budget of 50k I'm sure you'll have the lighting to compensate.

Speaking of budget- wow...$50,000- that's not cheap! Granted it's a drop in the bucket compared to a Hollywood film but it's nothing to shake a stick at. Especially beings the only work I've done was on a $0 budget...or my own wallet- which, by the way, doesn't run that deep- not even close.

Good luck with it man- let us know when your done I'd love to see it when it's completed!

*btw, how'd you score a deal filming something of this magnitude?! And secondly, if you dont mind me asking...how much of that 50k is cut for your salary? :) *

[Ron Little]

Scoring the gig is a product of being in the right place at the right time and saying something like

“I could do that just as good if not better for less money.”

Can you say open mouth insert foot.

It got me the gig it also cut my pay oh well live and learn.

[Jeff Kilgroe]

Ron,

This if you're using the DVX100, then by all means shoot in 24p! That's what the DVX100 is for. If for some reason you consider going to 60i, then you would probably be better served with a Canon XL1S with its much more versatile capabilities and available lenses.

I have both of these cams and I bought the DVX100 specifically for 24p. Good 24p can look very good if you take the time and do a proper transfer to DVD with 24p pulldown flags.

Other than that, your other choices would include trying to buy or rent some higher end DV cameras like the Ikegami models... I can't begin to estimate how your budget works out, but for a $50K feature that will see video release and possibly more, I would seriously try to rent an HDCAM and shoot in HD... Provided you can get access to the system and equipment to edit.

[Stephen van Vuuren]

If you shoot 24p, which will clearly give you a look more suitable to narrative horror story (unless it's a Blair Witch must look like video live news thing), and will give you much higher quality at the DVD and compositing stages (24 frames vs 60 fields), make sure to do your homework well.

Check out the resources here in the many threads discussing how to best shoot, edit and output 24p. And if you are going to film (or probably), it's mandatory to talk to a film house or five that already has experience in taking 24p progessive video to film before you make a single production decision.

[Rodger Marjama]

For any interested... I've put up a ZIP file with a couple of MPEG2 encoded clips inside. These clips are encoded from the same source footage using exactly the same perimeters with the exception of one being converted for 24p DVD authoring and the other for 30i DVD authoring.

They a just short clips produce by ICExpo showing a girl talking. They where shot using Panasonic's anamorphic adapter in 24pa. I converted the footage to 24p and for the 24p DVD clip, and used the unconverted file for the 30i encodes.

Click here and then click on "24p .vs 30i DVD" on the website's page.

Note: This was posted in another forum where some discussion about 24p and the reality of 24p DVD authoring was being discussed. Since I've been doing 24p DVD's for many months now, I thought I'd post some simple footage converted from ICExpo's anamorphic talking clip he made awhile back for some to look at, and since it was done with the DVX100 and Panasonic's anamorphic adapter, I thought I'd post here for any interested as well.

-Rodger

[Mike Morrell]

Roger, would you post a link to the other forum discussion? I'd like to read it.

[Steve Mullen]

Someone posted the lux value for the DVX100 when in 24p mode over in the JVC HD list.

Can this be reposted here -- and your source.

I remember 24lux.

Thank you.

[Andre De Clercq]

Joseph George posted 24 lux on june 23. Others posted 100 lux...
Like I remarked a couple of months ago, the camera sensitivity specs as mentioned in the spec sheet are, apart from the missing S/N figure, not consistent : F11/2000 lux doesn't corelate with f1.6/3 lux /+18db/ 50 IRE. If we considder p and i modes (both in full dutycycle) equivalent w.r.t. the sensitivity spec (which is pretty close) then we get 42.3 lux calculating from the F11 spec. Calculating from the F1.6/...spec, we get 120 lux for ful video (remember 50IRE is ~ 20 % light level!)

[Steve Mullen]

Whoops, too fast for me.

The F11/2000-lux is at 0dB gain?

So, simply opening the iris to f1.6 (4+ stops) drops the lux from 2000 to 125/100 -- which makes sense to me.

Where then does the DVX100's 24p, 24-lux value come from?

IF the F11/2000 were at 100IRE (which I think is true) then the lux would be 50 at 50IRE. (No gain in 24p mode.)

However, my understanding is that in the USA the lux standard WHEN ONE DOES NOT use a "F??/????-lux" PRO specification, is only 25IRE. If I'm corrrect, then the lux rating would drop to 25 at the CONSUMER 25IRE standard. (Again, no gain in 24p mode.)

Now if the DVX100 sensitivity is 25-lux (for 25IRE) with NO gain -- then with 18dB gain, could it be 3-lux?

I ask the questions because I always forget how to do the math with dB?


Since the JVC HD10 35lux is rated in Japan, where the Consumer standard is 50IRE, its USA consumer rating would be 18-lux. Of course, that's with +6DB gain. Which means it's actually slightly more sensitive than the DVX100 IF you enable AGC.

Without +6dB gain, it would be either 36-lux or 72-lux. Math with dBs???

Comments please!