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Old December 28th, 2004, 06:54 PM   #16
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There is not UV filter attached. IT is possible to mount one 4inch round filter in the Lens/sunshade but that is an odd size and I don;t have any!

Why are you asking? Do you think the footage with the WA adapter on it looks darker? Cause I have wondered if I am losing light through it.

Thanks!
Anyone else?
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Old December 28th, 2004, 07:54 PM   #17
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Hi Marty. That's not why I was asking, but now that you mention it, the reds (on the Santa) with converter seem a little bit muted compared with those without.

What prompted my question was I was just wondering if there was something out of the ordinary that you could be doing that might affect the focus. Clutching at straws, really. :)

Richard
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Old December 29th, 2004, 08:13 AM   #18
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I think it's a good idea to email Century Optics with your findings or try posting this in the DVXUser forums as well since that may improve the chances Bill can see this. I'm very curious as to why this happens, and am wondering if I shouldn't just get the Canon 3X wide angle instead. Also, does this happen with the manual lenses on the XL2?

Thanks for the updates, Marty, appreciate the clip.

As for things to try, is OIS turned off?
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Old December 29th, 2004, 09:03 AM   #19
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<<<-- Originally posted by Christopher Go : I think it's a good idea to email Century Optics with your findings or try posting this in the DVXUser forums as well since that may improve the chances Bill can see this. I'm very curious as to why this happens, and am wondering if I shouldn't just get the Canon 3X wide angle instead. Also, does this happen with the manual lenses on the XL2?

Thanks for the updates, Marty, appreciate the clip.

As for things to try, is OIS turned off? -->>>

I have tried OIS on and off and it is the same. As far as the manual lens doing this, I don't actually know as I don't have it.

I don;t yet know if this is normal or if it is the way these particular wide angle adapters react. It might be a limitation of the converter itself or maybe it is out of spec? I really don;t know for sure.

I was hoping to get some input form fellow DVinfo members who have used it on the XL1 to see if they had this issue.
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Old January 3rd, 2005, 01:18 PM   #20
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Here is the reply I sent privately a few days agoin response to an email received at the office. While I understand why at first blush the converter would seem to be the culprit, it is very unlikely.

My response:

First of all I am sorry I was unable to respond sooner, I have been using up some excess vacation as the year ends.

Please bear with me, because it is extremely unlikely that there is anything wrong with your .7X converter.

We would be happy to inspect and test your unit if you send it to us.

We have a Canon XL2 with the 20X lens here. I have personally evaluated the .7x on this lens. The lens is very similar to its predecessor the 16X. We have sold thousands of these for use on the Canon XL1 and the Panasonic DVX-- with very few complaints or problems, so while I will not say it is impossible that the unit is defective the problem you describe does not seem consistant with a problem in the converter.

If you achieve sharp focus at maximum telephoto and the image goes soft as you zoom wider the zoom lens itself is the likely problem. The .7x effectively reduces the focal length of the zoom. Depth of focus, the area of acceptable sharpness on either side of optimum focus (forgive me if you know this-- it is sort of like depth of field but at the image plane instead of the object plane) gets smaller and smaller as the focal length becomes shorter.

This can mean that if your lens has a slight backfocus problem, or the zoom curve is almost out of spec, it might seem ok (tho you say you are seeing "something" in the lens alone) but be unacceptably soft with the .7X in place.

If you zoom in auto focus mode does the lens remain sharp?

The converter contains no moving or focusing elements, and once you focus thru it and achieve sharp focus it should not change as you zoom wide--- unless the problem is in the lens.

The most critical test of the quality of the converter is typically at telephoto. The converter does have some lateral chromatic at wide angle and as is typical in converters (and the lens itself) is not as sharp at the edge of the field as it is in the center-- but is still very good.

Please email me and let me know what you would like to do next. If you bought the camera from a local store I would see if they would allow you to try the .7X on a different camera, or put a different lens on your camera and see if problem persisits.

It will be most noticeable when the lens is near wide open. Stopping the lens down increases the depth of focus.

Best Regards

Bill Turner
Century Division
Schneider Optics
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Old January 3rd, 2005, 01:23 PM   #21
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Bill,
I sent you an email response directly.

Marty
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Old January 26th, 2005, 01:37 PM   #22
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Hello Marty et. al. Thank you all for the work done re the .7x. For us, the .7x + 20x as a "standard" setup would work very well so we were interested in the outcome of the work done in resolving this concern. Please let us know, TIA.
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Old January 26th, 2005, 02:03 PM   #23
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Here is a link to the images I sent to Bill Turner.

http://www.iciclestudios.com/images/...pare/index.htm

As of last week he was taking the Xl2 they have at Century and testing it thoroughly with the .7x adapter to see if they have these issues. I have tried 2 different .7x adapters and the results are the same.


It seems that I can work around this annomaly with a careful use of good lights and a fstop around 4-5. A field monitor is almost necessary because if you are just a tiny bit out of focus in the center the edges seem to really blur. And you really can't see it in the viewfinder.

The problem with this is I bought the .7x for run and gun stuff where I am not ina controlled studio environment. I already had the .6x but hated taking it on and off. The .7x was supposed to make life easier but instead has been a much pain in the butt! I can get good shots with it but there is an exponentail increase in out of focus and blurry shots with it. I am better of not using it or switiching to the .6x until I here from Bill about his findings. His comment to me was that they have sold a lot of these adapters and in all honesty if there was a problem he would think he would be hearing it from all over. So we will see.

Thanks!
Marty
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Old February 1st, 2005, 02:43 AM   #24
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In case anyone is still interested in the 0.7X converter, I got to test one out today at my local dealer, using a 14" Sony production monitor to check the focus sharpness. Based on Marty's valuable feedback, I set the aperture wide open to make any focus drift more obvious.

Anyway, I could not see any focus shift with the converter fitted. For what it's worth, I also tried a slow zoom on auto focus and the image stayed sharp over the whole range.

If anybody has a reason NOT to buy this converter, please don't post it here, because it's too late for me! :)

Richard
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Old February 1st, 2005, 08:24 AM   #25
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Richard,
On auto focus the adapter works ok as the camera constantly refocuses electronically as you zoom out. Therefore the camera adjusts if the focus were to drift. If you use autofocus that is fine. I almost never do and never had to with my xl1. Again the 20x lens by itself is doing fine.

What I notice more than anything is that the focus on the outer rim of the lens on the .7x is very touchy. If you have the center of the image focused exactly and not even off by a fraction the image tends to look good. However if you were off by the tiniest bit (almost undetectable by the human eye) then the focus falls off sharply as you look to the edges of the frame.

Where I am having the biggest problem is if I am shooting a person 20 feet away, I zoom in, set the focus and it looks dead on. I zoom out to frame the shot based on that and the focus will drift just a hair in the center of the lens. In the viewfinder it still looks crystal clear. What I can't see in the viewfinder is that the edges are now going soft. If I have a field monitor and focus based on the new wide angle I can get a sharp picture across the frame. But if I change the zoom I am almost guarenteed to have a soft focus in the frame.

I have not given up on this adapter but I have not heard back from Century about their "checking to see if they can reproduce the problem" and Canon has sent back my XL2 saying the lens is in spec. So at the moment I have a near unusable combination. If I had the luxury of setting up a field monitor and double checking every single shot to make sure that the focus is perffect I would have the time to switch the 20x lens and the .6x century adapter that does not zoom through, based on that particular shots focal needs. But I don't have that luxury and the .7x was supposed to make life easier. It hasn't.

The final statement I can make regarding this is this. I have used the Xl1, dvx100 and now the Xl2. I have never had problem focusing in manual mode and always have had good results based strictly on using the Viewfinder. For whatever reason when I add the .7x adapter onto the XL2, I find later, after a shoot, that a large ammount of the images are soft. Not only that but a large ammount look in focus in the center and have edges that look like they are blurred using a filter. It is annoying to say the least. This sample below shows you what I see a lot. I shot all of these by zooming onto the far wall, focusing, then zooming out. See what I am seeing here?

http://www.iciclestudios.com/images/...pare/index.htm
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Old February 1st, 2005, 05:33 PM   #26
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Last week I checked a .7X Century Wide Angle Converter taken at random from inventory. I used our own Canon XL2 and 20x lens that was purchased from a dealer from random stock.

I found that it held focus thru the range, both in manual and auto modes. I performed the tests wide open and examined the live images on a Sony 19" monitor in underscan.

While some loss of edge sharpness and increased chromatic abberation was visible at the edges at the widest angle, I saw nothing as pronounced as what appears in the samples.

I am at a loss to explain the problem, other than re- iterate that there are no moving parts in the converter and that having the image drift in and out of focus when using the converter can not be due to a defect in the converter.

As mentioned previously, it is conceivable that because the shorter focal length resulting with the converter has a smaller margin for error in back focus, that a back focus error in the zoom that is not noticeble (or at least objectionable) in the lens alone might become a problem when the converter is added.

Other than examining this particular example on the off chance that something is loose - tho I am not sure this could cause the problem either- I am at a loss to explain the problem being experienced.

As I have also said, we have sold several thousand of these converters configured for various cameras and have had very few complaints or dis-satisfied customers, if a basic flaw in the design and function of the unit existed we should have been made aware of it long ago and had many many complaints-- and we have not.

Bill Turner
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Schneider Optics
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Old February 1st, 2005, 08:59 PM   #27
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Well that is quite depressing to say the least. I am stuck with a 20x lens that doesn't want to play nice with the .7x adapter. I have had 2 .7x adapters and the results were the same on both units so I am inclined to believe that there is not anything wrong with the adapter itself. But if Canon claims that the lens is within spec what can I do?

I would like to know if the .7x adapters vary through the years. I am currently using a .7x "value" series adapter that was modifed by century to fit the Xl2. I also bought a brand new .7x for the Xl2 and it says "pro series" on the casing. IS there any difference there? Because I sent back the brand new one since the optical quality is supposed to be the same on both.

Canon is surely not going to replace my 20x lens when they say it is in spec to begin with.

So while others may be having luck I am left out in the cold on this one. I will be borrowing a 16x ISII XL1s lens to test it on in a few weeks.

Seriously bummed here in Ohio

:(
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Old February 1st, 2005, 10:52 PM   #28
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Marty, I think that the problem is with the 20x lens. If you zoom in get critical focus and then zoom out, the lens' focus point will shift. It has nothing to do with the converter. Try it without the converter, it will shift.

Because the lens is driven by electric brushes and not really mechanically, you will lose your focus point. EF is fine if your a stills photog, but for video, you absolutely need to be able to zoom and not have your focus mark move. You should buy the manual lens.

I'm not sure what kind of crack the design team was smoking, but I think the 20x lens blows.

This isn't a backfocus issue.

I posted my findings about a week ago about critical focus with the 20x auto lens.
http://www.dvinfo.net/conf/showthrea...threadid=38166
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Old February 2nd, 2005, 01:04 AM   #29
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Mark, the focus does not necessarily shift when zooming, or at least, it shouldn't shift by an objectionable amount. I think this is a problem with how Marty's lens is adjusted rather than the basic design. Otherwise everybody would be seeing it too. I think your own tests are somewhat special because the follow-focus mechanism is probably not intended to be used with a servo-focus lens.

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Old February 2nd, 2005, 01:26 AM   #30
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I was skimming the threads so I may have missed something. There is a follow focus gear for the 20x lens, I've got one. Hand focusing makes it worse. I have used the .7 W/A converter on my 20x with no problem. I was in manual focus.
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