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Canon XL and GL Series DV Camcorders
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Old May 14th, 2005, 12:23 PM   #1
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Stock Canon XL2 DOF really that bad?

Hello all,

Forgive me for my concentration of posts. After investigating several cameras to use for independent film production, I've settled on the XL2. I'll be picking up one in the next month or so and I want to get a feel for some of the accessories I'll need.

Back to the topic...

Is the stock DOF on the Canon with the 20X really that bad? I read of people trying to overcome DOF issues with Mini35 contraptions, etc. and I wonder exactly how little DOF they are trying to achieve.

To make my shorts (films, not underwear) look like film, I'm obviously going to want to limit DOF somewhat. For instance, if I want to shoot a conversation between two people, as one is talking, the camera will shoot over the shoulder or across the face of the other in the foreground. I'll want to have that foreground somewhat out of focus when the actors are anywhere between 4 and 6 feet apart. Some of these shots will be indoors, so I won't be able to back away and zoom all the way in. I'll imagine I'll have to use the other method of getting very close to the actor that is not speaking. Additionally, I'll try to get the background (walls, furniture, etc.) as far away as possible to also get them out of focus. They will probably be another 7 to 10 feet behind the actor that is speaking.

My question is: will the stock Canon XL2 with the 20X be able to accomplish what I want? Or...

Will I need to get a diopter lens to get closer to the foreground?
Will I need to rig up a makeshift mini35?

My gut feeling is that the stock XL2 is good enough to do what I want and the others are using special equipment to really press the limit of DOF.

What are your thoughts?

Thanks,

Kelly
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Old May 14th, 2005, 02:28 PM   #2
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Hi Kelly

The DOF from the XL2 will be the same as on any other 1/3 prosumer camera, exept for the 4/3 modus, because then you actually use 1/4 of the chips.
But if you want to make short movies, I think you'll use the 16/9 anyway.

Is it any good? I have an XL1s, and if I put my iris on 1.8 I have a nice DOF. For me enough to work with.
Maybe it isn't 35mm DOF, but it's definately enough I think for what you want to do.

You can buy the mini 35, but that's 10.000 dollars for a more limited DOF... I think you can spend that money in a better way for maybe audio, lightning, actors...


Good luck!
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Old May 14th, 2005, 03:35 PM   #3
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Quote:
Originally Posted by Mathieu Ghekiere
Hi Kelly

The DOF from the XL2 will be the same as on any other 1/3 prosumer camera, exept for the 4/3 modus, because then you actually use 1/4 of the chips.
But if you want to make short movies, I think you'll use the 16/9 anyway.
Thanks Mathieu.

I've never had a 1/3 prosumer camera before. Could you expand a bit on you DOF. For instance, in the shots I illustrate above, would you be able to get the foreground and background easily out of focus?

Thanks,

Kelly
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Old May 14th, 2005, 08:34 PM   #4
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Mathieu is referring to the aspect ratio of the camera. The XL2 is a native 16x9 camera. You are using all of the frame and all of the pixels when you shoot 16x9. When you switch to 4:3, you are using about three quarters of the usable picture area, so your focal length gets slightly longer. Here is an explanation of the XL2 Chip block:
http://www.dvinfo.net/canonxl2/articles/article06.php

If you do a search for depth of field, you will see many discusions about it. I suggest you read, that will help.

Generally, if you can zoom to the tele end of the lens and shoot at the widest aperture, that will help limit your depth of field. If you can scout your locations and do some tests, that will help. You can always rent a Mini35 and some Zeiss Super Speed primes, you don't necessarily have to go and buy one. Depending on what you want to accomplish in your film, do some tests and see what you like.
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Old May 14th, 2005, 08:58 PM   #5
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Mark, thanks for your response. Yes, I've extensively researched the depth of field issue on the XL2 along with how it applies to general digital videography in general. I've been able to understand the techniques and I'm confident I'll be able to put them in motion once I start shooting.

However, I'm not really asking about DOF in general. I'm wondering how bad the issue is with the XL2 specifically.

This is basically a pre-purchase question. Without buying anything extra, can someone give me examples of how shallow the stock XL2 is with the 20X lens?

I've given some examples of shots I'll probably be doing. As a pre-purchase question, I'm wondering if the stock XL2 can do them.

To sum up a typical shot:

In order of distance from camera: subject one, 4-6 foot space, subject two, 7-10 foot space, background imagery/wall. The entire shot would be a mid close up of dialogue.

Question: I would like to keep the camera stationary and shift focus back and forth from subject one to subject two while keeping the background slightly out of focus. Can this be done with a stock XL2 with a 20X?

Note: I did not specify the distance between the camera and subject one on purpose as I imagine you'd have to play around with either being very close to subject one or as far away as possible and zooming in to get the DOF shallow. However, I couldn't be more than about 8 feet away from subject one.

Also, I don't need to know HOW to do this...I already basically know how to try this (distance away and zooming vs getting close, opening up the aperture, etc.). The question is whether the stock XL2 DOF can be made this shallow under these conditions.

I have to imagine that anyone with an XL2 and a 20X who has spent any time at all working with DOF should be able to answer this question on this hypothetic shot.

Thanks,

Kelly
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Old May 14th, 2005, 09:35 PM   #6
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Run, don't walk, to http://www.dvinfo.net/articles/optics/dofskinny.php
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Old May 14th, 2005, 09:44 PM   #7
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Quote:
Originally Posted by Chris Hurd
Excellent link. I'll plug in some figures and see what I come up with.

Thanks,

Kelly
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Old May 14th, 2005, 10:25 PM   #8
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Quote:
Originally Posted by Kelly Wilbur
I have to imagine that anyone with an XL2 and a 20X who has spent any time at all working with DOF should be able to answer this question on this hypothetic shot.
I don't have an answer because I don't have any information. What is your focal length? What is your subject distance? What is your f/stop? Without knowing all of these things it's impossible to say and it's different in every situation. That's stuff you'll have to figure out for yourself using the depth of field calculations. Be far away and like I said before, stay towards the tele end. If you are at the wide end, you'll have deep depth of field. That's what you get with MiniDV and video in general.

The 20x does not lend itself to accurate focus pulls, unless you do it at exactly the same speed in both directions. Even then it'll probably drift, I did some tests and posted about it in January, or December. Use the 16x.

Do some tests.
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Old May 14th, 2005, 10:38 PM   #9
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Quote:
Originally Posted by Mark Sasahara
The 20x does not lend itself to accurate focus pulls, unless you do it at exactly the same speed in both directions. Even then it'll probably drift, I did some tests and posted about it in January, or December. Use the 16x.

Do some tests.
I'll try to work with the DOF calculations although some of it is still abstract to me. I guess you are right. I'm probably going to have to wait until I get the camera and experiment with this myself. Ultimately, I imagine I would want to open the lens as much as possible and zoom in as much as possible. How much I can zoom in will be balanced with how far I can move back away from the subject and still be able to frame the shot properly. Lots of things to balance.

As far as the focus pulls, is it that hard to do it by sight, especially if you don't have to pull that fast? I don't want to use the 16X because of the issue with the frame drifting.

Is this why people are rigging up "follow focus" rigs? I always wondered why they didn't just focus during a shot by what they saw in the viewfinder. I may end up posting this as another thread, but is the purpose of a "follow focus" just to mark specific focus marks that can be repeatable without having to rely on your eye?

Thanks,

Kelly
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Old May 14th, 2005, 11:57 PM   #10
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http://www.cinetechonline.com/ Look at the picture, it shows the follow focus attached to the XL2. Not enthused about the 20x as the lens. I have a Cinetech Titanium II follow focus which was about $1500, but a great deal and will work on any 15mm rods. It includes a short whip and knob.

The follow focus rig is helpful because it isolates the movements of the camera asistant so that the camera is not jerked during focus pulls. A flexible extension, or "whip" can also be used if the camera is handheld, or moving. This allows focus pulls without interfering with the free movement of the camera. The white disk can be written on with erasable pen to mark the focus point, or points, allowing you to repeatedly hit the same mark(s) with accuracy.

Usually the 1st AC measures the distance from the camera to the subject and then sets the lens to the appropriate distance. The operator may look through the camera to double check. It sounds wierd, but it's very accurate. With film cameras, and even with some video viewfinders measuring is sometimes more accurate than eye focus. The best AC's know the distance and can estimate very accurately the distance and then turn the knob appropriately and achieve sharp focus without looking through the camera. Cine lenses are also marked with the distances more frequently, every foot or so.

When I have to pull focus myself, I use white 1/8" Chartpak tape and stick it on the focus ring and make the marks there. I am left eyed, so while looking through the viewfinder, I can simlutaneously pull focus, but I am still using the follow focus, it just makes it easier.

Having someone else pull focus makes it easier for the camera operator to concentrate on following the subject or making sure that certain compositions/frames are hit during a take. Though I think the NFL Films guys all operate and pull their own focus. (Sound byte of Paris Hilton) That's hott.

You will probably find yourself in the corner, or out in the hallway. Somehow I am always doing this, tryng to get as far back as possible. Sometimes it helps if there are just blank walls behind the subject.

Depth of field calculations help to determine your near point and far point of focus, or acceptable sharpness. Outside of those distances, the subject begins to go out of focus. Not sure what the circle of confusion for a 1/3" chip is. Not sure anyone has ever bothered to find out.
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Old May 15th, 2005, 01:21 AM   #11
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You may want to check out the micro35 Cinema Lens Adapter. It gives you mini35 style adapting of 35mm lenses, but at a fraction of the price - intro price is $500.

www.micro35.com

Cheers

Brian
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Old May 15th, 2005, 02:35 AM   #12
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Getting back to your original question, Kelly...

The XL2 20x zoom on the XL2 is okay for DOF at a max f-stop of 3.5 at the tele end of the lens - not the best. Because the focal length has to be so long to get a decent DOF, you need to get distance from your actors, so when filming in tight spaces, you won't get what you want. I was a little disappointed because the lens really does just compress the z-axis without blurring it (must be because of the higher-res CCDs). While I have yet to use the Canon 3x Zoom XL lens (f/2.2 at full zoom), I've heard that the DOF is phenomenal when shooting medium and close-up shots.

My research as a student of digital cinematography has led me to think people want DOF to be too complicated to explain. It is when you get into the physics of light and lenses, but all you need to know is that the larger the f/stop, the shallower the depth of field.

Here's what I believe to be the best "cinema-like" DOF for SD video cameras to pull focus for scenes like you are describing (assuming you're using 1/60 sec shutter speed): 1/4" = f/1.8; 1/3" = f/2.0; 1/2" = f/2.2; 2/3" = f/2.4. The closer the lens can get to these f-stops at full telephoto, the shallower your depth-of-field.

Not many camcorders can achieve these fast lens speeds at full telephoto (usually max iris is 2.8 or higher). What I do to achieve the best DOF, is to always shoot with the largest f/stop through out a camera's zoom range, use ND or controlled lighting to control exposure, and shoot around the middle of the lens for most shots. (XL2 20x zoom = f/3.5, shutter 1/60, 55mm for most shots)

If you want some serious DOF, give a look to Canon's Optura Xi. Its lens at full telephoto is f/1.9. Yes, it's a 1-chipper and the exposure controls are not fully manual, but the quality of this camera is on par with the GL2. The Optura XI shoots native 16:9 and the image doesn't suffer from the 'softness' of the GL2 and XL1s because there is no pixel-shifting.

Hope this helps.
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Old May 15th, 2005, 06:39 AM   #13
 
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Quote:
Originally Posted by Kelly Wilbur
For instance, if I want to shoot a conversation between two people, as one is talking, the camera will shoot over the shoulder or across the face of the other in the foreground. I'll want to have that foreground somewhat out of focus when the actors are anywhere between 4 and 6 feet apart.
Unless I am mistaken, this is your real question. The truth is, this is going be almost (but not entirely) impossible to accomplish with your interior shots using the stock lens. And to be sure, this is not an issue limited to the XL series of cameras!

If you want your movie to look like it was shot on film, why not shoot it on film?

Jay
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Old May 15th, 2005, 07:49 AM   #14
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"If you want your movie to look like it was shot on film, why not shoot it on film?"

This is a real easy question to answer: time, money and expertise.

1.) Video setups are significantly easier to accomplish with less people.
2.) You can use less lighting.
3.) Video cameras are smaller than film cameras (less attention getting).
4.) Video cameras are less intimidating to on-camera talent.
5.) Light meters are built-in to the video camera; don't have to know exposure real well, since you can preview on monitor (WYSIWYG).
6.) 12-min roll of film + processing + color timing + telecine to DV = $$$$ vs. $4 for a 60-min mini DV tape. Think about how much money per minute you spend for usable footage on film (for every 12 minutes, probably 2 or 3 min is usable). Rewind the tape if you must and rerecord. It's still only $4.
7.) Edit immediately - no waiting.
8.) Video can now shoot 24 fps for that telecined-look.

Also, ask someone who isn't familiar with the film/video world to spot the difference between the two formats and chances are, they can't.

Another thing that I find interesting is digital projection in movie theaters. I went to see Hitchhiker's Guide to the Universe in digital, and some of the previews and commercials shown before the film were obviously done in video. I was rather amazed at the quality of the video being projected that large. Also, more features are being shot in HD (i.e. Star Wars)... you'd never know it wasn't on film. Think about this too - most visual effects are recorded to film at a 2K resolution. HD is basically 1K - almost there.

The only thing film has to it, is the elusive ease at which to achieve DOF. Every other quality of film can be mimmicked with video.

Let the flame wars begin :)
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Old May 15th, 2005, 08:37 AM   #15
 
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I don't entirely agree or disagree.

1.) Video setups are significantly easier to accomplish with less people.
Not related to achieving "film-look."

2.) You can use less lighting.
Not related to achieving "film-look." In fact, this will only contribute to the problem!

3.) Video cameras are smaller than film cameras (less attention getting).
Not related to achieving "film-look."

4.) Video cameras are less intimidating to on-camera talent.
Not related to achieving "film-look." If the on-camera talent is intimidated by the camera, then they need to look for work elsewhere!

5.) Light meters are built-in to the video camera; don't have to know exposure real well, since you can preview on monitor (WYSIWYG).
Not related to achieving "film-look." Can be and is done with video assist in film.

6.) 12-min roll of film + processing + color timing + telecine to DV = $$$$ vs. $4 for a 60-min mini DV tape. Think about how much money per minute you spend for usable footage on film (for every 12 minutes, probably 2 or 3 min is usable). Rewind the tape if you must and rerecord. It's still only $4.
Not related to achieving "film-look."

7.) Edit immediately - no waiting.
Although true... Not related to achieving "film-look."

8.) Video can now shoot 24 fps for that telecined-look.
Not entirely.

Also, ask someone who isn't familiar with the film/video world to spot the difference between the two formats and chances are, they can't.
Most can, although they can't explain why.

Moot points to the real question of achieving a film-look.

Jay
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