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-   -   16x Manual lens breathes-Waah! (https://www.dvinfo.net/forum/canon-xl-gl-series-dv-camcorders/36504-16x-manual-lens-breathes-waah.html)

Mark Sasahara December 16th, 2004 10:38 PM

16x Manual lens breathes-Waah!
 
I was shooting with the Canon 16x manual lens on my XL2 and everything was great.

That is, until I had to rack focus for a scene and the lens breathed in a really bad way. I had to stop and put on the 20x auto lens which, to my surprise, did not breathe. I used the 20x on the rest of the production.

Has anyone had a problem with their 16x manual lens breathing? It makes the shot look like I'm zooming while I rack. I have used older cine lenses on film cameras that have breathed a little, but this was ridiculous.

I am currently waiting for my own Cine Tech Follow focus rig, but it was a real pain in the butt to have to pull focus on the 20x auto lens with no FF gear. I'm seriously thinking of getting rid of the 16x. Luckily Cine Tech now makes a gear for the 20x, but I really like the 16x because it's geared and doesn't do that whole infinite focus ring thing.

I'm curious to hear if other folks have the same problem. I called ZGC (who are great), where I got my whole package from and they said it's a flaw of the lens.

I'd really like to give Canon a piece of my mind. This is unacceptable. Do their other broadcast lenses breathe? Alas, I fear that because this is a prosumer lens they don't care.

Who do I contact at Canon?

Charles Saeger December 17th, 2004 12:29 AM

I've never heard that term before, what do you mean when a camera "breathes"?

Also, where are you purchasing your Cinetech follow focus from? Do you have their matte box as well?

Mark Sasahara December 17th, 2004 12:54 AM

Breathing occurs when the focus point of a lens is changed and the angle of view changes slightly by either widening out or zooming in. It appears as if the frame is breathing. This flaw is not desirable. There shouldn't be any movement noticable other than the shift in focus. The picture should not seem to zoom in, or out, when racking.

Say I have a two shot and the camera is locked down. One person is five feet away and the other person is ten feet away. When I rack focus from one to the other, the lens seeming to slightly zoom in or out as I rack back and forth between the two people is very distracting.

Mark Sasahara December 17th, 2004 01:23 AM

I have the Chrosziel Matte box, but I'm still waiting for the bracket and rods. I was going to get either the Cine Tech Mini Follow Focus, or the Universal. Now, I'm contemplating getting the Studio FF but that's $2500. Oy!

A. J. deLange December 17th, 2004 07:27 AM

What he means is that the focal length changes as you vary the focus distance and yes, my 16x does it and it isn't subtle either! It's much more noticeable at short focal length where the depth of field is greatest because things tend to stay sharper irrespective of where the focus ring is set and you can really see the zoom. Interesting!

Matthew Cherry December 17th, 2004 09:36 AM

Does this happen with the 14X Manual as well? I'm contemplating getting one of these lenses and up until now was planning on going with the 16X...

John Lee December 17th, 2004 11:06 AM

I've used the full manual 16x extensively on the XL1s, and I've had the same problem. Never knew there was a term for it before, and it was really only noticeable when I was shooting for a high DOF.

If the backfocus were set incorrectly would that amplify this problem? If so, that may have been the case for me.

Charles Papert December 17th, 2004 03:31 PM

Lens breathing is always more of an issue with zooms than prime (fixed focal length lenses), and is a function of the number of lens elements and sophistication of the lens. For the relatively low price of these lenses, a certain amount of breathing is expected. You will see it on the 14x manual as well as the 16x. The best way to hide breathing is to make a small move (pan or tilt) during the rack. Some may find the degree of breathing present with these lenses to be objectionable, others may not be concerned.

Mark Sasahara December 17th, 2004 06:50 PM

Yeah, I've been compensating with small moves, but to alleviate the problem I've been using the 20x lens. I'm waiting for the FF gears to come from Cine Tech.

I don't mind the 20x it's a nice lens, but it looks really goofy, like a giant marshmallow. It's the infinite focus that bugs me. I believe the Cine Tech has a lockout for that .

I'm just really disappointed that it breathes.

I'm going to go bite my pillow now.

Jimmy McKenzie December 17th, 2004 09:51 PM

You might want to find one of the older generation 14x manual lenses and test this. I can rack between the 2 objects with great precision and there is no measureable "swelling" or breathing of the frame. Perhaps this is because the 14x has a manual ring to control not only the zoom but also the iris. Even so, it is a cheap lens at only 900 bucks...

Mark Sasahara December 17th, 2004 11:06 PM

That shouldn't be a factor, it's the design of the lens itself that causes the image to breathe.

I will certainly consider an older lens. Silly me for thinking the newer lens would be better.

Chris Hurd December 17th, 2004 11:37 PM

I've seen this "effect" but never knew the proper term for it. Thanks Michael,

Charles Papert December 18th, 2004 06:10 PM

In my freshman (and only) year at NYU's film school, I found myself camera assisting on a bunch of senior and grad student films with the Arri 16BL. This camera used the Angeniuex 12-120 zoom in a big blimp housing (this lens has been discussed in this forum as an inexpensive way to mate PL film optics with a mechanical adaptor to the XL1). This is a notoriously "breathy" lens--you really notice the magnification effect when spinning the focus substantially.

On one film, I had to rack from close focus to infinity. No follow focus was available for that camera, and the blimp housing made rack focusing difficult--you had to literally use two hands to rotate the barrel! When the footage came back, the director accused me of hitting the zoom lever when I was focusing. I suggested that since it had the same effect every time and for the same amount, perhaps something else was causing this. None of us were apparently aware of the phenomenon of lens breathing...I guess we all learned eventually!

Bill Pryor December 18th, 2004 08:44 PM

Yep, those old Angenieux 12-120 lenses breathed more than a dirty old man at a porn flick. All zoom lenses do, some more than others. Primes will too but the better the lens, the less it breathes. Usually it's not too horrible with a good zoom lens except under certain circumstances, like when you are focused down to 3-4 feet and then shift focus to 30-40 feet. You can experiment with different focal lengths--for example, try moving the camera farther back from the foreground subject, so that instead of being, say 4 feet from it, you are 10 feet, but zoom in tighter to the area you want. The lens I use on a DSR500 (my 15 year old Nikkor ED 8.5-127mm) really breathes when I'm focused down to that closest range. If I can get back to beyond 10 feet or so, it's not nearly so noticeable.

Aaron Koolen December 19th, 2004 06:55 PM

Well I see breathing in pro production films all the time - I just assumed that it was just one of those things.

Also Mark, assuming you use the 20x, aren't you still going to lose the ability to reproduce focus pulls due to the nature of the lens? How is that Cine Tech thing going to solve anything other than giving you a different way to turn the barrel?

Aaron


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