Achieving shallow DOF without a Mini35

[Steve Gibby]

The new Mini35/HD100 footage looks great and it is refreshing to see some shallow depth of field from a 1/3" camera! Great job Charles, Nate, and Barry...

For real mobile production with the HD100, where shallow DOF are desired, and a Mini35 and primes are not needed or practical, I think we'll be able to get fairly shallow DOF by using a Century 2x extender between the the HD100 and the 16x or 13x Fujinon lenses. In many genres of television production prime lenses aren't used. The new Fujinon 13x seems to be a good quality HD lens, and with the 2x between the lens and HD100 it seems like it would still be a real mobile setup with good resolution and DOF capability. Subjects and scenes would have to be lit well, because the 2x will probably cause you to lose a stop.

For mobile SD productions in 480i60, 480p60, or 576p50 it seems the 2x extender combined with a 1/2" to 1/3" converter could be used with a longer focal length lens like a 1/2" Fujinon 20x or Canon 19x to get some shallow DOF.

If the HD100 is placed farther back from the subject and ND filters are used it should also make achieving shallow DOF easier...

[Barry Green]

The HD100's stock lens is capable of getting a quite shallow DOF effect all on its own. It's reasonably long, 88 mm (twice the length of the DVX, and as long as the original Canon 16x lens). So as long as you can get back far enough, you can get very shallow DOF.

The problem is that the chromatic aberrations are far more noticeable when you're using that much telephoto.

Have a look at this clip, it demonstrates both effects.
http://www.icexpo.com/HD100/chroma-aberration.wmv
In it, I'm rack-focusing on two different surfaces of a wine glass, from the front surface to the back surface. You can see that when the front is in focus, the back is most definitely out of focus. The downside is the enormous purple and green fringe around the reflections of the lights in the glass -- those shouldn't be there at all; the lights shining on that glass were white and they should have been rendered white.

[Steve Gibby]

Very good observations for the 16x - an $800 lens. The 13x ($12k lens), and for SD, the Fujinon 20x and Canon 19x (both $4k lenses), shouldn't suffer from the chromatic aberrations you found in the 16x, and thus be good tools with a 2x and ND filters for getting clean shallow DOF footage from the HD100.

[Barry Green]

With the 13x, you would probably want the 2x extender, yes. And at a max of about 90mm (3.5 x 13 x 2) you would get similar shallow depth of field effects.

Someone posted that they could get the 13x lens, FOB in Miami for something pretty cheap (comparatively), like $8000 or so. And a JVC rep at the WEVA booth (won't say who) said that he thought the lens would be a lot less than $11,995. So the 13x may be a more practical option than it has heretofore been thought!

[Steve Gibby]

Nice! At NAB I was impressed by the clean images of the 13x on the HD100 - no apparent barrel distortion, smooth motion, etc. The uncompressed out to HD-SDI, to good CRT monitor helped to give a good indication of what the 13x can do. If it comes way down below $10k I'll be stoked! I need one for my types of TV production: sports, documentaries, nature, etc - not to mention stock footage acquisition.

[Mathieu Ghekiere]

Can I ask the maybe stupid question why that 13x lens is sooo expensive? Especially in comparisson with the other lens that ships with the camera?

[Charles Papert]

Remember that by moving the subject back and zooming in, thus maintaining the same image size, the DoF characteristic remains the same. You only get a shallower depth of field if you go telephoto AND you can allow for a larger image size (subject stays close).

[Barry Green]

Originally Posted by Charles Papert

Remember that by moving the subject back and zooming in, thus maintaining the same image size, the DoF characteristic remains the same. You only get a shallower depth of field if you go telephoto AND you can allow for a larger image size (subject stays close).

In theory, but not in reality.

In wide-angle, even when getting close, there's a whole lot more background visible in the shot (the reason is, because the wide angle has such a wider field of view, and the telephoto uses such a narrower field of view).

So when going close and zooming out, you'll see a lot more background than you will when you back up and zoom in.

So even though the elements of the background that you're seeing are equally sharp (or equally out of focus), they'll APPEAR much more out of focus in the telephoto shot. The telephoto shot optically magnifies a very small piece of background to fill the screen, and that magnification makes it appear as if it's a lot more out of focus than it actually may be (just like zooming in on a photoshop document can make something look blocky and un-sharp, but if you shrink down your window it looks a lot sharper and more in focus). Same effect with optics: the wider the field of view, the smaller each element of the background, and therefore the more in focus it looks.

I demonstrated this effect by shooting an identical subject at max. wide angle, and getting close; and then max. telephoto, and backing up so that the subject size stays the same. For an equivalent subject size, the telephoto shot's background looks *noticeably* more out-of-focus.

http://www.icexpo.com/dvx100/DOF-Combined.jpg
I split-screened it, the shot on the left was done by backing up and zooming in, the shot on the right was done by zooming all the way out and getting close. Both shots used an identical aperture.

[Barry Green]

Originally Posted by Mathieu Ghekiere

Can I ask the maybe stupid question why that 13x lens is sooo expensive? Especially in comparisson with the other lens that ships with the camera?

Because the lens that ships with the camera is ridiculously cheap. The least-expensive high-def lens on the market, that I can think of, is $12,000. The 13x lens, when it comes on the market, will be the new least-expensive high-def lens available. Far from being sooo expensive, it will actually be the least expensive.

The lens that comes bundled with the camera is, basically, a "giveaway". It is not something by which the standards of high-definition lenses should be judged.

[Chris Basmas]

Barry are you talking about 1/3" hi-def lenses? I think the prices you quote are for 2/3" lenses?

[Barry Green]

The $12,000 figure was for a 2/3" lens, yes. Other than the JVCs, I'm not aware of any 1/3" HD lenses.

[Chris Basmas]

Than $8k is too expensive for a 1/3 inch lens. It's a lot less glass in there and cheaper to make. Some won't even consider 1/3" as a professional lens.

[Charles Papert]

I get your point Barry--it's actually an illustration of the Papert school of cinematography (if I may!!);it's not about the numbers or the theory, it's the image itself that counts.

Still and all, there are many reasons why shooting at extreme telephoto just to get a bit of softness in the background can invite many other issues. Shooting an over-the-shoulder shot can be a real pain in the arse, for one thing--you virtually have to lock the actors in place to maintain the desired composition, and forget about dollying left or right to correct for it (a very common way to deal with this--you make your adjustment when the person who's back is to camera speaks, i.e. an off-camera line). And a bunch of other reasons and issues, like having to shout to the actors! But I won't go further into off-topic land.

[Mathieu Ghekiere]

Originally Posted by Barry Green

Because the lens that ships with the camera is ridiculously cheap. The least-expensive high-def lens on the market, that I can think of, is $12,000. The 13x lens, when it comes on the market, will be the new least-expensive high-def lens available. Far from being sooo expensive, it will actually be the least expensive.

The lens that comes bundled with the camera is, basically, a "giveaway". It is not something by which the standards of high-definition lenses should be judged.

Ow thankyou, seems like I was just plain wrong then :-)
Thanks for the answer

[Steve Gibby]

Originally Posted by Chris Basmas

Than $8k is too expensive for a 1/3 inch lens. It's a lot less glass in there and cheaper to make. Some won't even consider 1/3" as a professional lens.

Those are the same guys who don't consider a 1/3" camera a professional. Others of us just keep using 1/3" cameras for our national television programs and laughing all the way to the bank! In the hands of an experienced professional, a 1/3" camera can a very professional camera, and yes, a 1/3" lens can be a professional lens - especially one that is engineered by a reputable maker like Fujinon.

Every day I use 2/3", 1/2", and 1/3" cameras for my national television porgrams. Myself and my shooters have the flick on how to maximize the capabilities of a 1/3" camera and lens and then broadcast the results. I think the old definitions of "professional" and "industrial" were more applicable in the days of Beta SP and Hi8. Nowdays, with the advent of 3-chip 1/3" cameras in DV, HDV, and DVCProHD (soon), it's risky assigning a 1/3" camera or lens a "non-professional" niche. Certainly the 16x lens is marginal, but having seen the results of the 13x on the HD100 at NAB I certainly would not agree with categorizing it as a "non-professional" lens.

If Charles, Nate, and Barry had also shot footage with the new 13x, I don't think they'd have any reservations in calling it a professional lens...