Flying 35mm

[John Jay]

what would be a realistic working DOF if you were flying a 35mm rig and wanted selective focus?

I am assuming the focus is locked off for the shot

[Rick Bravo]

Flying ?

What kind of 35mm rig?

What do you mean by "selective focus"?

I'm just a little confused.

RB

[John Jay]

Well I suppose I was a little bit woolly LOL

Heres the grainy version :)

Suppose there exists a 35mm adapter that can be mounted to a camcorder and further mounted to handheld Steadicam Jr type rig.

Then if I wanted slim DOF but also taking into account the fact that there will be some movement between camera and talent, I need to know what is a realistic working DOF so the talent remains in focus with average steadicam skills.

This will affect my choice of lens(s)

[Dmitri Henry]

John
I think in the situation like this the DOF of the lens is dependant on the distance between the lens and the subject. I couldn't know if the subject of your project is 50 or 5 feet away. If you play around with the aperture and the lighting you will get your perfect selective DOF. In increase of the illumination of the scene the aperture could be closed down a bit to minimize the DOF for your own needs. This can work visa-versa though i am not exacty sure if this is 100% since i am still learning. I hope i touched your question in some way or another.

[Charles Papert]

John:

This is the first time I have seen this question posed, although I have been waiting for it considering the current shallow DoF craze going around the DV world.

Let's take a 25mm lens, for example. It's a fairly wide angle lens, so we can expect somewhat more leeway in DoF (i.e. a greater range than a longer focal length lens). Set at a 2.8, we frame up a medium shot of the actor, just above the waist, which results in our distance being 6 feet. Setting the lens at 6' gives us from 5' to 7'7" in DoF, in other words between a foot and a foot and a half of variation. In practice, with that lens you could probably get away with another 6" in front and a foot in back. So you have a bit to play with. But this assumes a shot that keeps a standard distance. What if you want to push in for emphasis at the end?

Tricky. And as far as being able to light to a higher stop, that's a big can of worms. Daylight exterior no problem, just stop down as needed, or at least until there are issues with seeing the ground glass or whichever technology of 35mm adaptor you might be using.

Bottom line is: shooting shallow DoF with 35mm and fixed distances with Steadicam will be very limiting. You will end up having to design shots around this issue, and it then becomes a question of which is more visually interesting; having shallow DoF or more dynamic camera movement? Personally, I vote for the latter if I had to make the choice.

Eventually there will be a low-cost wireless focus unit that will solve this issue for the DV world. Until then, you are thinking in the right direction, John! (p.s. using a handheld JR-type device with a 35mm adaptor and lenses--ouch! Time to start eating that spinach, Popeye!)

[Wayne Orr]

Want to figure out that depth of field for various focal lengths and various f/stops? Here is that link (again).

http://www.panavision.co.nz/main/kbase/reference/calcFOVform.asp

Wayne Orr, SOC

[Charles Papert]

If you have a Palm device, this software (in particular, Pcam) is the BEST. It even lets you preview the image size a given focal length and distance will deliver via a pictoral representation.

[John Jay]

Charles,

How does an all up weight of 2.5 kg sound to you?
- (that's 5lbs of imperial potatoes :))


You suggest approximately 3ft (1metre) for a working DOF, I must confess that sounds ok to me.

I agree totally about the difficulties and yes I am looking for a look which is not often seen, so the shots will be designed for effect, starting wiith simple slow trucking and maybe some walking shots (though this will require several takes to get right), the trick will be to stick like glue with the talent at a constant-ish distance


It might even improve my steady skills

[Charles Papert]

5 lbs camera weight--not too shabby!

Still and all, anything over 4 lbs is a lot to carry. Just make sure to keep putting the rig down or shifting it to the other hand when not shooting! Fatigue shows up very quickly in the operating itself.

Yes, 3 ft is workable--but then again, if you are looking for a noticeably soft background, you won't see that with this lens and f-stop. A longer lens, shooting at 1.4...this will help but then your useable DoF will probably cut down to a foot or less.

I did plenty of this type of shooting in my early days of Steadicam, before I could afford a radio follow focus. It was all video and 16mm though. I'm not sure I've ever done a fixed-focus 35mm shot.

This reminds me of a rather fascinating exercise in math that I had to undertake while we were shooting "Mr. 3000" last summer. We had an incredible setup wherein we shot a pitcher against green screen throwing a fastball, shot at 2000 frames per second. We shot on stage with a truly staggering amount of light; the Lightning Strikes modules which are like the most massive strobe lights you can imagine, were lined up one after another to illuminate the pitcher and the entire path of the ball. I forgot what the total wattage was, but it was immense. You had to wear sunglasses when it went off.

Anyway, there was no chance at doing a manual follow focus of the ball at 100 mph flying right at the camera, so we set a series of fixed focus points knowing that the ball would start soft and then come into and eventually out of focus during its travel. I was in charge of doing the calculations to figure out at a given focal length and distance, what the depth of field would be (easy enough) but also how long onscreen that would last (took a bit of doing, considering having to convert high frame rates to real time on screen, plus the speed of the ball). The pCam and pCine were instrumental in this. The results were pretty cool in the final fillm, although these day one just assumes CGI was used for anything interesting!

[Rick Bravo]

Charles, you need a better first! :)

RB

[Charles Papert]

Believe me Ric, we tried a few "follow the ball" racks just for fun--at 2000 fps, that fastball takes about 45 seconds to travel to the mound, which is an eternity if there was a "momentary" (becoming endless) buzz!

[Rick Bravo]

I hear ya!

I worked on a commercial with Nolan Ryan about 20 years ago and I swear, that thing broke the sound barrier. To add insult to injury, I was using, probably, the last operational Mitchell BNC in Miami at the time. It was owned by the production company!

I also had the priviledge of getting behind the plate while he threw 3 fastballs at me.

I only saw the ball two times...

Once as it left his hand...

and,

Second, after it hit my mitt!

Damn it hurt!!!

Still typing with my right hand only!

RB

[Charles Papert]

I spent a lot of that movie last summer shooting through Lexan as the ball was hurled directly at me; trying not to flinch when that sucker WHAMMED! near my head over and over. The old evolutionary instincts kick in and you just want to run.

[Rick Bravo]

There's allot to be said for ingrained survival skills. The funny thing is that Nolan and I were shooting the breeze between setups when, just thinking out loud, I wondered what it would be like to catch a 100mph+ fastball.

He was very accomodating!

Gives you a greater appreciation for the person who can connect with a piece of wood at just the right instance in time to make the ball rocket in the opposite direction!

That is the wonderful thing about this biz, whether it is the "mainstream" film industry or any number of the manifestations thereof...

Regular folk can get to go places, meet people and do things that are just not possible in one lifetime...on a day-to-day basis and it is all, just in a day's work!

RB

[John Jay]

Charles,

Thx for Pcam link

next purchase -- a sonic measuring device....