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Canon XL and GL Series DV Camcorders
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Old January 19th, 2005, 06:59 PM   #31
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<<<-- Bill, yes the 20x auto lens will be able to hit focus marks because as part of the Cine Tech follow focus kit I got, there is a geared ring to go around the lens' focus ring. That interfaces with the gear on the follow focus drive. That's how a ff works, once the gears are enmeshed, you can repeatedly hit your focus marks and do pulls. . -->>>

Hi Mark. This is very interesting, but I always thought that the amount of focus adjustment on this lens varied with the SPEED of turning as well as the angle (of course I could be wrong about this). Have you actually confirmed that this attachment works consistently even if you turn it at different speeds? Thanks.

Richard
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Old January 19th, 2005, 08:17 PM   #32
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Yes, I do it every day. The speed at which you turn, doesn't matter, you just achieve focus faster, or slower. I am talking about focus, NOT zoom. If you have seen a follow focus, or used one, you'll know what I'm talking about.

http://www.zacuto.com/Chrosziel%20%20follow%20cine.htm
For an idea of what a follow focus looks like, check out the photo of the Chrosziel follow focus on a video camera (Sony?[random pic I grabbed for illustration]). This may help if you've never seen one before.

This thread is for the 16x manual lens. Look at the focus ring and you will see distance markings on the focus ring. These are repeatable with or without a follow focus. Six feet is six feet on that lens. A follow focus just makes it easier to hit the marks accurately. In the Zacuto picture, the big white disc is for writing your marks. Turn the big knob and the gear turns the lens' focus ring. There is a witness mark just above the white disc at 12'clock. That never moves but the disc does and so you can see when you're on the mark. Note that usually the First Camera Assistant is pulling focus while I operate the camera.

We're getting a bit off topic. Do some research and you will find pics and see how it's used.
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Old January 19th, 2005, 09:22 PM   #33
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Mark,
You have given the impression that the follow focus works on the 20x servo lens. I think that is what we are asking. It is obvious that it works on the 16x manual but some of your comments sound like you have been able to make it work on the servo. IS this so? I know there are limitations if it does but even getting it to work consistently at all is a big plus.

And I second the theory that the servo is both speed sensitive and motion sensitive. Meaning a movement of 1 inch slowly will give one focus result and a movement of 1 inch fast will focus farther.

Any thoughts?
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Old January 19th, 2005, 11:04 PM   #34
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Cine tech makes a gear ring for the 20x auto lens. I have it and I'm not afraid to use it.

No, the fast/slow thing does not apply. I don't know what you are talking about.

Click on the link below and see what I'm talking about:

http://www.cinetechonline.com/

I have to go and finish my pizza and wings (too much fat and grease)...

Okay, I've mucked around doing it fast and then slow. No difference.

P.S. Have y'all been following the links I've been making? They're dynamic. I thought for sure I've made a bunch on this thread.
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Old January 19th, 2005, 11:10 PM   #35
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So if you stay within the range of the focus and don't turn it beyond the point where the focus ring spins but the lens has stopped it is completely repeatable?

If that is the case then hooray! I was under the impression that the darn thing was speed sensitive? So you can mark focus points and hit them them repeatedly as long as you don't exceed the max and minimum focus of the actual lens? I understand that the thing would be all messed up if you hit autofocus or turn it off but for that particulat session you could count on it?
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Old January 19th, 2005, 11:19 PM   #36
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<<<-- Originally posted by Marty Hudzik : So if you stay within the range of the focus and don't turn it beyond the point where the focus ring spins but the lens has stopped it is completely repeatable?-->>>

Yes, the follow focus has a stop so you don't go beyond.

<<<-- If that is the case then hooray! I was under the impression that the darn thing was speed sensitive? So you can mark focus points and hit them them repeatedly as long as you don't exceed the max and minimum focus of the actual lens? I understand that the thing would be all messed up if you hit autofocus or turn it off but for that particulat session you could count on it? -->>>

If you were to turn on AF it would probably cancel your marks and you would have to reset them. I'm not going to mess with it now, I have to go to sleep and wake up in a few hours. I'm in manual focus pretty much all the time.
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Old January 19th, 2005, 11:34 PM   #37
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I never use anything but manual focus either. But I am trying to think of things that would mess up the calibration if you will.

Thanks.
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Old January 20th, 2005, 12:10 AM   #38
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Mark, thanks for the confirmation. I tried the link you provided, but can just see a huge list of bits and pieces that I can't make much sense of. How do you know which bits you need to buy to make up one complete follow focus unit? (Hopefully not ALL of them!) Is there a follow focus KIT somewhere that is easier to understand?

Richard
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Old January 20th, 2005, 08:33 AM   #39
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I just looked at the cinetech link as well. The picture they have on the home page shows the follow-focus being used on a XL-2. I wonder if there is something about the 20x servo lens for the XL-2 that makes it possible to hit marks. That deffinateily is not the case with my 16x servo. Too bad!

Does anyone know what they changed on the 20x servo, to make the focus ring direct drive?

Maybe we should make a new thread.
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Old January 21st, 2005, 01:28 AM   #40
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The 16x manual can hit the same marks with or without a follow focus because it's mechanical. The 20x auto lens is all electric, I believe. I will get confirmation on this, but after a few conversations with people, I'm beginning to get the idea that the 20x drive mechanisms for both the zoom and the focus are electric, rather than a mechanical linkage. That's why the the feel is different and that may explain why some peple are reporting focus effects dependent upon speed of the focus ring being turned. That is probably why there are no permanent markings for focal length or focus distance.

So, I'm waiting for Canon to come out with a full set of prime lenses for the XL2, similar to the FJs HD prime lenses line for 2/3" HD cams and some super-wide zooms with more than a 3x range. 2mm-60mm?

http://www.usa.canon.com/html/indust...me_lenses.html








Okay, any time now...



...
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Old January 21st, 2005, 02:04 AM   #41
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Oops, you were talking about the older 16x auto lens.

You could probably stick a gear on that too. It's just that with the auto lenses, they are electro focus, so if you power down the camera all your marks are worthless. The 20x auto and 16x auto lenses may both be the same circumference.
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Old January 21st, 2005, 09:07 AM   #42
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Mark, you got me confused now. Does the follow focus work repeatably with the 20x lens or not? Losing the settings on power down is not really an issue for me, just whether it hits the marks or not.

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Old January 21st, 2005, 10:17 AM   #43
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I made a new thread because I think that this has gotten off topic.

"Follow-Focus for 20x servo lens works how?"

I'm going to put my reply there.

Cheers
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Old January 21st, 2005, 01:59 PM   #44
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Richard, yes follow focus works semi-reliably with the 20x.

I am focused on the screen in my window approx. six feet away and the bricks of a building about one hundred feet away. The far mark, on the building seems to drift a bit, but the near mark is pretty consistent. I am at a telephoto focal length and my f/stop is f/2.0 with the full ND in the lens being used. There is some play in the Cine Tech follow focus. I'm trying to get as shallow a depth of field as possible. The marks are pretty good for the 20x.

I am trying closer points. My near point is 11' 5.5". Far point is 27' 11". I am using a Stanley 100' steel tape and anchoring off the metal block that holds the rods on my Chrosziel matte box bracket. This approximates where I imagine the CCD block to be, but I have no idea. My marks are high contrast: black tape against a white wall (near) and backlit frosted glass (far). Illumination gets me f/2.0. I'm at approximately the same focal length as the manual 16x lens which was 48mm.

I notice that if you only shift between the near and far marks, the focus is consistent. If you go way past the marks and then go back, they are oblitereated and you have to set new marks. But if you keep with the two marks, they appear to be consistent.

Also I have to take into account the play in the follow focus, I'll see if I can tighten it up a bit. This seems to affect the results. There is some backlash which results in the mark shifting when you let go of the knob. This may be because the mechanism has a belt to drive the gear.

I did the same distances with the 16x manual lens and it is more consistent

Actually, I wasn't paying attention and the battery died. So I shut off the camera, switched out batteries, and my marks were the same. I tried it again by turning off the camera, waiting about thrithy seconds, then turning it back on and they remained consistent.
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Old January 21st, 2005, 03:21 PM   #45
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Hi Mark,

I guess my attempts to move this thread out of the subject of breathing lenses is not going to work, so I'll fall into line.

I'm very interested in wether this follow focus works like I wish it would. And since you are kindly trying it out for us. If you would tell me how this goes with your set up, I would be most grateful:

If using the same situation that you had set up in your last entry; you snap the focus from the far point to the near point really fast, are the marks still accurate?

Do this again with a really slow rack, as slow as you can go, and tell us if the marks are still good.

Thanks.
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