I've got all three lenses and find that I use the 20x most often. Beware of the focus hunting problem with the 20x, however, I beleive it's a tad sharper than the 16x manual. For my money, I'd invest in a good quality 6x9 monitor before I'd invest in a B&W viewfinder.

If you go with the 20x and want to do artistic work, you'll almost certainly decide you need the 3x. The 20x is a long lens -- just plain not wide enough at the short end. The two together give you quite a lot of zoom range!

I've never used the 16x so can't comment on that. Here's good info posted by our fearless leader:

http://www.dvinfo.net/canonxl2/articles/article10.php

We'll look forward to seeing your work!

Follow-Focus for 20x servo lens works how?
 

http://www.cinetechonline.com/index.html

The picture shows a follow-focus being used on a XL-2 20x servo lens. I wonder if there is something about the 20x servo lens that makes it possible to hit marks. That definitely is not the case with my 16x servo.

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

Hi Daniel,

There is no real difference there. You should contact Karl Horn of CineTech and get his input regarding the ability of that lens to hit marks using his follow focus rig (er ist auch ein Deutscher, übrigens). And then please report back and tell us what he told you.

Thanks Chris,

I will.

I just wrote an email to Cinetech:

"Are there any limitations, that I should know about, using the Cinetech Follow-Focus with my 16x servo lens? Like the Follow-Focus system is not designed to just make focusing "easier", is it?

I'm asking, because I find it hard to believe that a mechanical focusing system can get around the spongy speed sensitive servo focusing ring of the Canon 16x!

Just to make sure I'm getting this right, once I have set marks with the Cinetech Follow-Focus system, I will be able to consistently dial to these marks repeatedly, regardless of the dialing speed? If the answer to this is yes, I don't suppose you would explain how this is achieved?

I'm sorry for being so skeptical, and I don't expect you to divulge any trade secrets. But I don't believe that what I have just suggested is possible with a simply mechanical device. Maybe you can convince me that the FF overrides the speed sensitivity of the servo lens, without us having to go through the hassle of an international parcel post demo. Or do you have a Rep. here in Germany, where I could try out the system?"

I'll let you know how they respond.

Canon 20x auto lens follow focus accuracy
 

The experiment
Can the Canon 20x auto lens repeatedly and accurately hit preset focus marks?

The equipment
Canon XL2 w/20x auto lens, 16x manual lens, FU-1000 B&W viewfinder, mounted on Vinten Vision 3 head on Vision Tripod. Chrosziel bracket and rod holders, Cine Tech Titanium SL follow focus unit w/ coarse and fine pitch drive gears, coarse pitch gear ring for 20x auto lens. The 16x manual lens was used as the control lens. A matte box was not required for this experiment, so stock lens shades were used.

Settings
Aperture-f/2.2. Focal length-48mm*. Near focus point-11' 5.5". Far point-27' 11". Distances measured with a Stanley 100' steel tape and anchoring off the metal block that holds the rods on my Chrosziel matte box bracket. This approximate CCD location is based upon WAG. High contrast marks were used.
Notes:f/2.2 is maximum aperture at 48mm on the 20x lens. *Focal length was determined using the 16x manual lens and then making framing marks for the 20x. Camera aspect ratio set to 16x9, in manual.

Results Summary
Question: Can the Canon 20x auto lens accurately and repeatedly hit preset focus marks?
Answer: Yes and no
Explanation: If you set your marks and do not go beyond them, or change the zoom, you should be able to get repeatable results. Focus speed does seem to have some effect in making the marks drift. I was doing rather small pulls approximately sixteen feet between the near and far marks. The marks on the disc were about 3/8" apart, so I couldn't really zip between the two very quickly, without overshooting the mark.

I then zoomed wide and adjusted the focus, quickly going back and forth close and far distances a few times with the focus knob. The marks were obliterated by doing this and I had to reset the focus marks. Zooming shifted the marks also. This means that you cannot zoom in, get critical focus and then zoom back out to your shooting focal length. I did this, zooming in focusing and then zooming back out and the marks shifted significantly.

Shutting off the camera and then powering up again several times did not affect the focus marks. On powering up the focus mark that the camera was set to was sharp and shifting focus using the preset marks on the follow focus disc were accurate.

Daniel, as part of the thread that this came from I have made a new thread with the results of my research on follow focus with the 20x auto lens.

"Canon 20x auto lens follow focus accuracy"
http://www.dvinfo.net/conf/showthrea...threadid=38166

This new thread you've started is good since I don't really know how the 20x auto lens works. Someone suggested that the firmware in the lens could be updated. This would be good because hard stops and footage/meter scales could be programmed in as well as a way to figure out what focal length you're at.

Can anyone hack the 20x?

Thanks Mark,

You have confirmed what I suspected. Too bad, I would have love to have had the possibility of snap-to accurate focus, along with the image stabilizing of the auto lenses. I like to do a lot of hand held tele shooting. I guess you can't always have your cake and eat it at the same time.

Your little test here, has burst a tiny bubble of hope, but it has saved me a lot of time and trouble getting it to burst on my own.

Thanks again.

Daniel: I'm wondering how you are going to do focus pulling and
do hand held shooting at the same time. Why not get the manual
lens to do the focus pulling when you need to (you should not
need OIS in this case anyway) and use the OIS lens when you
are going hand held.

Hi Rob,

I have found the image stabilizer on the 16x servo lens to be so good that my preferred method of shooting is with the lens very telephoto, and the camera braced under my arm. I'm not really only interested in focus pulls, I would like to be able to focus the servo lens consistently and be able to use techniques like judging the distance to the subject. What I would really like is a manual lens with the servo's image stabilization. But if there were such a thing, it would probably be out of my price class.

As to using a follow focus hand held, I'll admit that it is somewhat awkward, and you sweat a lot, but it is possible. And I have gotten good results shooting like this, with, and without an assistent. There are some prime lenses that are so stiff, you can only focus them with an arm or a FF.

Cheers,

So if you are handheld in low mode I assume you are in a wide
angle shot? Do you really need that critical focus then? (since
your DoF should be pretty large)....

I like to shoot with a long focal length in this mode. Because I really like the look of the shallow DOF. Shooting from the hip like this also allows me to add a little movement to the camera and adjust to how the person or persons I am filming move. Without the stabilizer, I wouldn't be able to do this with half the focal length. I'm not into dogma style shaky camera work.

proper filter for 20X lens protection?
 

I'm not up much on filters at the moment, and need to find out what kind of filter I need to buy to protect my 20X lens from getting marked or scratched. I don;t want a filter that will minipulate the image, mainly for protection. Someone told me that it might be called a UV filter or Daylight filter? and would it be suitable for both interior and exterior shooting?
Thanks ahead of time.

Re: proper filter for 20X lens protection?
 

<<<-- Originally posted by Joseph Andolina : what kind of filter I need to buy to protect my 20X -->>>

Most likely Canon has a 72 mm filter called "Protect" as an accessory to the EF-series lenses. That should be a neutral glass and that should fit to the 20x lens. Ask some Canon rep./dealer about such filters. (I have myself a Canon 77mm Protect "filter", and pretty sure the same exists in other size.)