Problem with the 3x on XL2? at DVinfo.net

Jeff Miller · November 18th, 2004, 09:02 PM

I was email'ing one of the sponsors about an XL2 quote and they mentioned trouble with the 3X lens, and to call for details. But I was swamped and they closed before I could call. The existing 3X threads on this board seem to state that there are no observable problems with the 3X. Is there _any_ known technical reason the 3X might not work well with the XL2?

On a side note, is a lens change on the XL2 big downtime? I've changed lenses on some big JVC's before, but only under rare circumstances (troubleshooting, etc). My immediate use for the XL2 will be run and gun documentary, and if I want to change lenses it means I'll have to carry another lens with me. That's possible, but dicey, and I'm terrified of getting crud on the bare "window" into the body. Makes me wonder if I should just get the converter.

David Lach · November 18th, 2004, 09:24 PM

If your plan is run and gun and you don't want to carry an extra lens, I would suggest geting the full zoom through wide angle converter and just leave it on. That way you can get wide or tele without ever bothering about changing lenses on the fly.

Pete Bauer · November 19th, 2004, 07:03 PM

Hi Jeff,

I use both the stock 20x and the 3x on my XL2 and both work great. "Down time" for changing lenses is the same as on a 35mm SLR camera...just takes seconds for the actual lens change. NOT COUNTING the time to carefully unstow and stow the lenses, of course! So let's call it a minute.

Presumably, for run and gun, you'd want to just leave the 20x on the camera. It is a "long" rather than "wide" lens (42.3mm to 846mm for 35mm equiv when shooting 16:9) -- but then it has a 20x zoom range so that covers a lot of ground! I'd just guess that you don't need to get in really tight too often for most run and gun work? But if, on occasion, you did need to set up a really wide shot, the 3x will do the trick nicely. You'd just need to be in a situation where, if you were carrying a 35mm SLR and needed to change a lens, you could do it. And, of course, the GL2 is a lot more portable and less attnetion-catching -- in case that's important to you.

Are you shooting 4:3 only? If so, you could get nearly as nice a picture from a GL2 -- also a 20x Fluorite lens -- and pay about a third as much for it plus a good wide angle adaptor as compared to the XL2 with the two lenses. The GL2 is less "long" and slightly more "wide" at 39.5-790mm in 35mm SLR terms, whereas the XL2 in 4:3 is 51.8mm to 1036mm in narrow screen. With a WD58H adaptor, you'd widen the GL2 to 28mm equiv.

In my book, the XL2 really shines because of its unmatched WIDE SCREEN image. But, if you'll be using wide screen, the XL2 and its interchangeable lenses rock...have no fear of THAT!

Just food for thought.

Bob Safay · November 21st, 2004, 07:58 AM

Jeff and others. remember to TURN THE CAMCORDER OFF before changing lenses to prevent and shorts in the contacts. Bob

Barry Goyette · November 21st, 2004, 07:34 PM

Jeff,

There is at least some anecdotal evidence (as in my experience, and a couple of others) that there is a back focus issue with the 3x on the xl2. I haven't had time to send mine in, but I got an email from a member who did, and was told by canon that they wouldn't be able to fix it...this is 3rd party so I can't say that all 3x lenses will have this problem...but mine does.

On the other hand..when focused..it's stunningly sharp...fantastic really.

Barry

Douglas Robbins · November 22nd, 2004, 03:26 AM

Now, what does "back focus" mean?

Douglas

Barry Goyette · November 22nd, 2004, 08:40 AM

Theoretically, a zoom lens with proper back focus will maintain its focus plane throughout its zoom range. My 3x lens, when focused on an object at full zoom, will lose focus as it zooms wider.

Barry

Jim Sofranko · November 22nd, 2004, 11:35 AM

Are you saying that the 3x lense will work great on the XL2 unless there is a back focus issue on the 3x which cannot be corrected on the XL2?

Is the back focus of these lenses somehow adjusted in the camera electronics??

Thanks.

Barry Goyette · November 22nd, 2004, 12:21 PM

JIm..

I'm saying this may be an issue...I have it...someone else has it... and he has not reached a conclusion with canon...

The manual 16x lens has a user adjustment, all others must be sent it to canon, (I'm not sure how they make the adjustment).

Barry

Buzz Bell · February 14th, 2005, 04:40 PM

I have heard (anecdotally) that Canon is aware that the 3X (with and without the 1.6 extender) will not hold focus over the range of the rack.
I was told Canon never intended for it to be used on the XL2.

I have proven the problem time and time again using 3X, pull in, focus, pull out - you are can now REfocus better than you should be able to. I am in 24p, 16:9 but doubt that is an issue, regardless - i am tired of yelling at my dailies after i trusted my focus settings on the 3X.

To its credit - when wide, the 3X plus the extender is nice for very large establishing shots where you can get away from vertical warping issues, but i was used to the XL1 where i could depend on the lense wherever i was in the focal range.

A. J. deLange · February 14th, 2005, 06:54 PM

Does that mean you don't see this problem on the XL1? I do on the XL1s.

Buzz Bell · February 15th, 2005, 10:46 AM

I shot with the XL1 for 18 months and the problem with the 3X was not there.

Rob Lohman · February 16th, 2005, 06:40 AM

Are you SURE it is loosing focus? Because it is known fact that
when you increase the field of view on a lens (zoom out) you'll
get an appearance of softening since you are spreading the
pixels across the image. The image will look softer at the wide
angle due to pixel averaging, the higher the resolution of the
camera the less apparent this is though (so it should be more
obvious on the XL1 than the XL2).

This effect is also more pronounced on large vistas etc.

Also see this thread (2nd to last post by Chris):

http://www.dvinfo.net/conf/showthrea...486#post236486

A. J. deLange · February 16th, 2005, 08:12 AM

Yes, absolutely. And here's the interesting bit. With the lens (iris) wide open and zoomed all the way out (minimum focal length) the best focus is full CCW whether you are focusing on an object (Sieman chart in this case) a few feet away or a tree line at "infinity"! This is true on both the XL1s and XL2 (on my XL1s and XL2 with my 3X lens anyway). Thus it's clear that the optical path from the flange to the chip surface must be different on the XL1 since it doesn't exhibit this behavior and we'd have to assume that any XL1 lens would perform differently on the XL1s and XL2 - not just the 3X (exception being those that have a back focus adjustment which the 16X manual does but I don't know about the 14X).

I suspect that it is not possible to focus this lens on distant objects when it is wide open. It feels as if you ought to go just a little further CCW to get things to snap in. This may explain why people have complained about landscapes taken with it (though aliasing could certainly also be an issue).

Remember that making a 3.4 mm (minimum focal length of 3X) lens is a real challenge. It isn't possible to have a back focus distance that short so the designers art really comes into play here. I guess the design trades were done to favor use in tight spaces and I suppose that is what this lens is really intended for.

Marty Hudzik · February 16th, 2005, 10:11 AM

For what it is worth I got to try the Canon 3x Wide lens for a while(borrowed from a friend) and I did see a bit of a backfocus issue with it on short distances. However outside on a "vista" type shot I zoomed and focused on trees over 100 yards away and zoomed out and the shot looked magnificent! However in a small 20 foot room I focused on a chair 15 feet away and zoomed out and it went out of focus. however the lamp that was 7-8 feet way was now sharp and seemed to mark the new focal plane. It's as if it moved closer as I zoomed out.

Since I was only borrowing I cannot comment on having it adjusted. If I bought one and it had this issue I would surely have it at the Service Center to be adjusted.

Having played with the Century Optics adapters for years I can honestly say that the Canon is the best looking wide angle adapter I have ever used. It is amazingly clean and sharp and with little barrel distortion at all. Great piece of glass.

November 18th, 2004, 09:02 PM	#1
Jeff Miller Major Player Join Date: Nov 2004 Location: St Louis, MO Posts: 227	Problem with the 3x on XL2? I was email'ing one of the sponsors about an XL2 quote and they mentioned trouble with the 3X lens, and to call for details. But I was swamped and they closed before I could call. The existing 3X threads on this board seem to state that there are no observable problems with the 3X. Is there _any_ known technical reason the 3X might not work well with the XL2? On a side note, is a lens change on the XL2 big downtime? I've changed lenses on some big JVC's before, but only under rare circumstances (troubleshooting, etc). My immediate use for the XL2 will be run and gun documentary, and if I want to change lenses it means I'll have to carry another lens with me. That's possible, but dicey, and I'm terrified of getting crud on the bare "window" into the body. Makes me wonder if I should just get the converter.

November 19th, 2004, 07:03 PM	#3
Pete Bauer Wrangler Join Date: May 2003 Location: Eagle River, AK Posts: 4,100	Hi Jeff, I use both the stock 20x and the 3x on my XL2 and both work great. "Down time" for changing lenses is the same as on a 35mm SLR camera...just takes seconds for the actual lens change. NOT COUNTING the time to carefully unstow and stow the lenses, of course! So let's call it a minute. Presumably, for run and gun, you'd want to just leave the 20x on the camera. It is a "long" rather than "wide" lens (42.3mm to 846mm for 35mm equiv when shooting 16:9) -- but then it has a 20x zoom range so that covers a lot of ground! I'd just guess that you don't need to get in really tight too often for most run and gun work? But if, on occasion, you did need to set up a really wide shot, the 3x will do the trick nicely. You'd just need to be in a situation where, if you were carrying a 35mm SLR and needed to change a lens, you could do it. And, of course, the GL2 is a lot more portable and less attnetion-catching -- in case that's important to you. Are you shooting 4:3 only? If so, you could get nearly as nice a picture from a GL2 -- also a 20x Fluorite lens -- and pay about a third as much for it plus a good wide angle adaptor as compared to the XL2 with the two lenses. The GL2 is less "long" and slightly more "wide" at 39.5-790mm in 35mm SLR terms, whereas the XL2 in 4:3 is 51.8mm to 1036mm in narrow screen. With a WD58H adaptor, you'd widen the GL2 to 28mm equiv. In my book, the XL2 really shines because of its unmatched WIDE SCREEN image. But, if you'll be using wide screen, the XL2 and its interchangeable lenses rock...have no fear of THAT! Just food for thought. __________________ Pete Bauer The most beautiful thing we can experience is the mysterious. It is the source of all true art and science. Albert Einstein Trying to solve a DV mystery? You may find the answer behind the SEARCH function ... or be able to join a discussion already in progress!

February 14th, 2005, 04:40 PM	#10
Buzz Bell New Boot Join Date: Jul 2003 Location: NYC Posts: 15	3X DOES have a back focus problem on XL2 I have heard (anecdotally) that Canon is aware that the 3X (with and without the 1.6 extender) will not hold focus over the range of the rack. I was told Canon never intended for it to be used on the XL2. I have proven the problem time and time again using 3X, pull in, focus, pull out - you are can now REfocus better than you should be able to. I am in 24p, 16:9 but doubt that is an issue, regardless - i am tired of yelling at my dailies after i trusted my focus settings on the 3X. To its credit - when wide, the 3X plus the extender is nice for very large establishing shots where you can get away from vertical warping issues, but i was used to the XL1 where i could depend on the lense wherever i was in the focal range.

February 16th, 2005, 06:40 AM	#13
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	Are you SURE it is loosing focus? Because it is known fact that when you increase the field of view on a lens (zoom out) you'll get an appearance of softening since you are spreading the pixels across the image. The image will look softer at the wide angle due to pixel averaging, the higher the resolution of the camera the less apparent this is though (so it should be more obvious on the XL1 than the XL2). This effect is also more pronounced on large vistas etc. Also see this thread (2nd to last post by Chris): http://www.dvinfo.net/conf/showthrea...486#post236486 __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

November 18th, 2004, 09:24 PM	#2
David Lach Major Player Join Date: Oct 2002 Location: Montreal, QC, Canada Posts: 570	If your plan is run and gun and you don't want to carry an extra lens, I would suggest geting the full zoom through wide angle converter and just leave it on. That way you can get wide or tele without ever bothering about changing lenses on the fly.

November 21st, 2004, 07:58 AM	#4
Bob Safay Trustee Join Date: Oct 2002 Location: Atlanta, GA Posts: 1,558	Jeff and others. remember to TURN THE CAMCORDER OFF before changing lenses to prevent and shorts in the contacts. Bob

November 21st, 2004, 07:34 PM	#5
Barry Goyette Trustee Join Date: Oct 2001 Location: San Luis Obispo CA Posts: 1,195	Jeff, There is at least some anecdotal evidence (as in my experience, and a couple of others) that there is a back focus issue with the 3x on the xl2. I haven't had time to send mine in, but I got an email from a member who did, and was told by canon that they wouldn't be able to fix it...this is 3rd party so I can't say that all 3x lenses will have this problem...but mine does. On the other hand..when focused..it's stunningly sharp...fantastic really. Barry

November 22nd, 2004, 03:26 AM	#6
Douglas Robbins Regular Crew Join Date: Sep 2004 Location: san bruno, ca Posts: 60	Now, what does "back focus" mean? Douglas

November 22nd, 2004, 08:40 AM	#7
Barry Goyette Trustee Join Date: Oct 2001 Location: San Luis Obispo CA Posts: 1,195	Theoretically, a zoom lens with proper back focus will maintain its focus plane throughout its zoom range. My 3x lens, when focused on an object at full zoom, will lose focus as it zooms wider. Barry

November 22nd, 2004, 11:35 AM	#8
Jim Sofranko Major Player Join Date: Mar 2004 Location: West Shokan, NY Posts: 217	Are you saying that the 3x lense will work great on the XL2 unless there is a back focus issue on the 3x which cannot be corrected on the XL2? Is the back focus of these lenses somehow adjusted in the camera electronics?? Thanks.

November 22nd, 2004, 12:21 PM	#9
Barry Goyette Trustee Join Date: Oct 2001 Location: San Luis Obispo CA Posts: 1,195	JIm.. I'm saying this may be an issue...I have it...someone else has it... and he has not reached a conclusion with canon... The manual 16x lens has a user adjustment, all others must be sent it to canon, (I'm not sure how they make the adjustment). Barry

February 14th, 2005, 06:54 PM	#11
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	Does that mean you don't see this problem on the XL1? I do on the XL1s.

February 15th, 2005, 10:46 AM	#12
Buzz Bell New Boot Join Date: Jul 2003 Location: NYC Posts: 15	I shot with the XL1 for 18 months and the problem with the 3X was not there.

February 16th, 2005, 08:12 AM	#14
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	Yes, absolutely. And here's the interesting bit. With the lens (iris) wide open and zoomed all the way out (minimum focal length) the best focus is full CCW whether you are focusing on an object (Sieman chart in this case) a few feet away or a tree line at "infinity"! This is true on both the XL1s and XL2 (on my XL1s and XL2 with my 3X lens anyway). Thus it's clear that the optical path from the flange to the chip surface must be different on the XL1 since it doesn't exhibit this behavior and we'd have to assume that any XL1 lens would perform differently on the XL1s and XL2 - not just the 3X (exception being those that have a back focus adjustment which the 16X manual does but I don't know about the 14X). I suspect that it is not possible to focus this lens on distant objects when it is wide open. It feels as if you ought to go just a little further CCW to get things to snap in. This may explain why people have complained about landscapes taken with it (though aliasing could certainly also be an issue). Remember that making a 3.4 mm (minimum focal length of 3X) lens is a real challenge. It isn't possible to have a back focus distance that short so the designers art really comes into play here. I guess the design trades were done to favor use in tight spaces and I suppose that is what this lens is really intended for.

February 16th, 2005, 10:11 AM	#15
Marty Hudzik Trustee Join Date: Jul 2004 Location: Canton, Ohio Posts: 1,771	For what it is worth I got to try the Canon 3x Wide lens for a while(borrowed from a friend) and I did see a bit of a backfocus issue with it on short distances. However outside on a "vista" type shot I zoomed and focused on trees over 100 yards away and zoomed out and the shot looked magnificent! However in a small 20 foot room I focused on a chair 15 feet away and zoomed out and it went out of focus. however the lamp that was 7-8 feet way was now sharp and seemed to mark the new focal plane. It's as if it moved closer as I zoomed out. Since I was only borrowing I cannot comment on having it adjusted. If I bought one and it had this issue I would surely have it at the Service Center to be adjusted. Having played with the Century Optics adapters for years I can honestly say that the Canon is the best looking wide angle adapter I have ever used. It is amazingly clean and sharp and with little barrel distortion at all. Great piece of glass.