View Full Version : focus slipping, iris acting funny


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Josh Bass
May 3rd, 2002, 08:02 PM
I got two new ones for you. First off, the focus on my Canon XL1s seems to slip sometimes. When I critcally focus and then zoom out to reframe, sometimes when I zoom back in, it's magically out of focus at some point! Why? It's in full manual mode, with everything manual, including focus.

Secondly, I've noticed that sometimes when I zoom in, toward the end of the zoom my iris closes a few stops! When I try to open it, it won't work until I've zoomed back out some distance. Why? Why? Dear God Why?

This is the 16x Is II zoom lens, or whatever it's called. . .the one that comes with the camera.

Chris Hurd
May 3rd, 2002, 08:17 PM
On the second issue, this is *perfectly normal* for a zoom lens... it will have one certain maximum aperture at the wide end, and another certain maximum aperture, not as open, at the telephoto end. *All* zoom lenses are like this, on video cameras and still cameras alike. You have to get into an *extremely expensive* professional zoom lens costing many, many thousands of dollars to get around this issue.

On the XL1, the maximum f/stops are f/1.6 at full wide at f/2.6 at full telephoto. Other camcorders in its class may have different max apertures than this but *all* of 'em will have different values at each end of the focal length, with the telephoto end a stop or two darker than the wide end. Look at any zoom lens, like the XL1 standard 16x, and it has two f/stop numbers, such as f/1.6-2.6 -- these are the different values for each end.

Obviously you'll need to light your scene for the telephoto end and shoot in aperture priority mode so that your exposure doesn't change while you zoom. Hope this helps,

Josh Bass
May 3rd, 2002, 08:37 PM
So I can't technically open any farther than 2.6 or so if I want to do a significant zoom. . .I see. I swear I never noticed it before. . .strange.

Chris Hurd
May 3rd, 2002, 08:46 PM
You should try lighting your scenes for the "sweet spot" of the lens which is around f/4.5 or f/5.6 if you can. I try to avoid being opened all the way up; depends entirely on what you're doing of course. Hope this helps,

Josh Bass
May 3rd, 2002, 09:32 PM
Now what is this sweet spot business? I've never noticed anything wrong with my iris being open all the way. . .especially if I want to emulate movie cinematography (e.g. blurring foreground) which is quite difficult to do with this camera (I've tried!)

Guest
May 4th, 2002, 04:07 AM
Chris,

On the 16x manual/servo lens, it stays at f 1.6 throughout the entire zoom range. I verified this after I purchased one.

Chris Hurd
May 4th, 2002, 09:58 AM
Thanks, I guess this is just with vari-focal servo zoom lenses with rear focus groups.

Josh Bass
May 4th, 2002, 10:21 AM
So how worth it exactly is it to get the manual zoom lens? I've read some other posts about it, and I know a lot of people say stick with the IS II. However, if I'm most interested in using the camera for making DV feature films (or something less dignified), as opposed to weddings, or documentaries, or the like, would it be a worthy purchase? Does it have back focus? I haven't found any info on that. It doesn't treat depth of field differently, does it? I read that its minimum focus distance is like five feet unless you're in macro mode. Would this make easier to achieve cinematographic effects (like the one I mentioned above)?

Guest
May 4th, 2002, 06:08 PM
SlashRules,

Does that have to do with G&R? I just saw a good G&R tribute band Thursday night. Anyway, all I can say is that for me the manual 16x manual/servo lens makes a huge difference. I know others like the 16x auto lens and the 3x lens which is fine, they are good lenses but not for my purposes. The 16x manual allows me to focus exactly on a point which is critical and it allows me to do this without even having my field monitor with me, just using the standard color viewfinder. I'm much more confident shooting with this lens and even though looks doesn't make a difference how you shoot, it does look more professional. Nothing is different in the depth of field issue, you are still using the 1/3" chips. However, rack focusing is a breeze compared to the other lenses. This lens has a back focus adjustment and it has 2 ND filters. If you are using this camera for filmmaking, save up and buy this lens, you'll be satisfied but until then, keep shooting with what you have. My next investment is to find a good, high quality zoom through wide angle adapter to use with this lens because personally, I didn't care for the 3x either. I hope someone makes a 2mm or 3mm prime for this camera which would be cool.

Guest
May 4th, 2002, 06:10 PM
One more thing, I think the minimum focus distance is 3.5 feet.

Josh Bass
May 4th, 2002, 11:19 PM
In regards to the manual zoom, really now? I wanted to get one sort of all purpose lens, and I thought the wide angle would be it, the only drawback being its short zoom range.

But you recommend the 16x manual. . .hmmm. Anyone else out there, what do you guys think? For filmmaking, that is?

Guest
May 5th, 2002, 07:30 AM
It's all the user's preference. For some, the standard lens and the 3x are fine, I just didn't care for them. Some people hate the XL1s and love the PD-150. Try out the lenses and see what you like best. For me, the 16x manual/servo is the only way to go.

Josh Bass
May 5th, 2002, 09:49 AM
That's cool. . .but can I ask why you don't like the wide angle? I'm just curious. I know in my budding filmmaking career that I will definitely need to get into tight spaces, where a wide angle would be handy. I'm just curious as to why the wide angle didn't do it for you. I 've heard nothing but praise from most people, except that it maybe isn't wide enough.

I believe you said you were looking for a good wide angle adaptor instead. Do they exist? I've heard they're always inferior to an actual lens. Let me know. Thanks.

Guest
May 5th, 2002, 09:58 AM
I do not like the focus control on both those lenses, both the standard 16x auto and the 3x. It's my personal preference, I love the XL1s, I've owned both the lenses (16x auto & 3x wide) and I was not pleased with those lenses. I like to be able to "feel" the focus point as with the 16x manual. I do not like a focus ring that keeps turning rather than having the precise focal point on the barrel. You really should try out the lenses if you can, there are many more out there who love the auto and 3x and are very pleased with the results.

Josh Bass
May 5th, 2002, 10:05 AM
Well, I totally agree on focus. I thought the wide angle was marked and calibrated and such. . .guess not, huh? Does it slip focus too. . .I've had that problem with the standard, where you critcally focus, then reframe, and when zooming in again, it's magically blurry!

I've also heard wide angle is a little soft? I don't know. Anyway, where could I try them out? I really don't know much technically about this stuff. . .so people's opinions are quite important.


More about wide angle adapters?

Guest
May 5th, 2002, 12:06 PM
You pretty much described what I don't like about the standard 16x auto and 3x, slipping focus and soft. The softness of the 3X in my opinion is due once again to the lack of control those electronic servo focus mechanisms have. Nothing is worse than getting into post and realizing what you thought was in focus actually was not. I've never ran into that problem with the 16x manual lens.

Josh Bass
May 6th, 2002, 03:41 AM
Ok ok . . cool. Several questions. Minimum focus distance is 3.5 feet (except when in macro mode) with the manual lens, correct? Okay, so. . .that makes me think maybe it's easier to do cool cinematographic effects with this lens (like blurring foreground, etc. Is this correct? Seems like you could just get "too close" to the area you wanted to blur, and focus on your subject, and all would be groovy. I've had little success achieving this effect with the IS II.

Also. . .have you figured out what to do when you do need those wide angles? Have you found a good enough adapter? Crystal optics has one. . .anyone know about it?

Mike Avery
May 6th, 2002, 07:38 AM
I just caught the tail end of this thread, but I agree with donbarzini about the benefits of the 16X manual lens.

I considered my XL1 an expensive toy until I put the manual lens on the front.

Now it's the first camera I grab.

If you are at all serious about videography, and you are frustrated by the standard lens.....go with the 16X manual.

Mike Avery

Josh Bass
May 6th, 2002, 10:13 AM
Well. . .rascals have opened my eyes. Is there a good way to get rid of the IS II an somehow make money off of it? Don't say ebay, because I got screwed pretty hard there once and I will never deal with those bastards or anything that resembles them again.

Also, good wide angle adapter? Anyone? Otherwise I'll be knocking down walls in every location . . .people might not like it

Chris Hurd
May 6th, 2002, 10:16 AM
Post it for sale right here in the Private Classifieds forum... every once in awhile, an XL1 owner looks to upgrade their IS lens to the IS II. Should be worth about $1000 or so.

Josh Bass
May 6th, 2002, 10:18 AM
1000.. .really? Hmmm. Groovy.

Guest
May 6th, 2002, 12:16 PM
I'm still searching for a good 100% zoom through wide angle adapter to use with the 16x manual lens.

Josh Bass
May 6th, 2002, 01:04 PM
Cool. Let me know if you find one. I don't much about them except what people say. Optex has a lens (not an adapter) that's fully manual, no communication with XL1s body, in other words. It's an adapted fujinon lens, I believe. There's an article about it on the XL1s watchdog site. I swear I saw it for $1000, but in the article it says it's like. . .$2300 or so? Something insane.

Chris Hurd
May 6th, 2002, 01:13 PM
Howdy from Texas,

Two things:

First, I have that lens and it is *not* a wide-angle lens. See the Guide to XL1 Lens Options on the Watchdog.

Second. the price in that article was from when it was new several years ago. It's much lower now. Hope this helps,

Josh Bass
May 6th, 2002, 04:31 PM
Ah. . .I see. Thanks. Is 16x manual's servo zoom smoother than the IS II's zoom?

Rob Lohman
May 7th, 2002, 03:28 AM
The manual lens does not use servos. That is the whole idea
behind a/the MANUAL lens. The rings are directly linked to the
underlying mechanisms.

Josh Bass
May 7th, 2002, 03:31 AM
Wait wait. . .I was under the impression there was a zoom rocker, and that you could switch between it and manually adjusting the zoom ring. ..

Josh Bass
May 7th, 2002, 03:38 AM
Here's an exerpt from an article on digitalfilmmaker.com

Now Canon has introduced a 16X manual lens that is able to work with the crucial elements of the power servo zoom and the camera auto exposure system. The black-barreled lens has a switch located on the bottom of the lens that allows it to easily be switched between servo and manual. What this means is that by leaving the switch in the manual position, it is possibly to quickly "snap" focus by racking between long and short focal lengths using the grip on the
barrel, or by switching to servo, be able to make smooth pushes and pulls

Chris Hurd
May 7th, 2002, 07:08 AM
It can get confusing to know exactly what we're talking about sometimes. The Canon 14x and Fuji-Optex 14x are manual only. The new Canon 16x manual lens includes a motor and is switchable between full manual zoom and motorized zoom. Hope this helps,

Rob Lohman
May 7th, 2002, 09:31 AM
My mistake. I was thinking about the "old" one indeed. My
appologies if I rushed any bushes.

danimalx
May 7th, 2002, 07:29 PM
there seems to be some confusion here regarding the manual lense and focusing these cameras.

first off, you cannot set a critical manual focus with any lens, using the color lcd viewfinder... the resolution simply isn't there, and the camera specs for the viewfinder bear this out.

in other words, if you want to set a perfect manual focus every time with any lense on these cameras, you'd better use the upgraded b/w viewfinder or an external monitor.

lets not mislead people into thinking that they can replace the lense, without also replacing the viewfinder.

wrt complaints about the stock is/isII lenses... i shoot a lot of motorsports videography, and there is no way that any non-stabilized lense can get the shots i get without a tripod... and even then some things can't be done.

yes, the focus problems with the is/isII makes 'em nearly unuseable for some purposes... but if handled correctly, it's a dream come true for run-n-gun video, or shots that require extreme zoom.


dan

Josh Bass
May 7th, 2002, 07:35 PM
I defer to the professionals out there for this. Who recommends the b&w viewfinder? We all know it sucks more power, and I believe there are other drawbacks though I can't remember them (obviously, the lack of color. But I have a 5.6 inch LCD monitor that can be camera mounted, and I can use it for checking color--it'll be reasonably close). So?

Josh Bass
May 7th, 2002, 07:36 PM
As far as run & gun video--I can always keep the IS II lens and use it when needed.

Ken Tanaka
May 7th, 2002, 10:56 PM
As Dan indicated, the b&w viewfinder is fairly essential for focus-critical and fine work. I've used it since day one. The XL1/XL1s b&w vf is actually made by Ikegami, one of the world's top professional video camera manufacturers. Yes, it does consume more power and it also somewhat confounds the early warning on the battery monitor. But it's higher resolution is fundamental for truly crafted focus. B&W also helps to keep your eye from being fooled in various ways. There's a reason why -all- profesional video cameras have high-res b&w viewfinders.

The color lcd is also handy to have for "run-n-gun" and other less critical work. It's lighter than the b&w and consumes much less power. But it's low resolution can make focusing difficult. It also crops the image (underscan) rather closely which can lead to mic booms and flags creeping into the frame undetected.

So I would certainly recommend the b&w vf for anyone who does professional work with their XL1s and can swing the expense.

Josh Bass
May 8th, 2002, 12:21 AM
Hmm. . .I never noticed the underscan problem. I plugged the camera into my TV one time, just to see how the viewfinder's frame compared with what showed up on a monitor (this might have been the wrong way to go about this. . .I'm sure someone out there will tell me), and found them to be the same.

As far as making sure color is okay when using a b&w viewfinder, I usually let it auto white balance, and have never had problems except in flourescent lit rooms. It usually auto balances better than I can do manually, at least to my eye.

Guest
May 8th, 2002, 04:12 AM
I have not had one problem so far using the color viewfinder with the new 16x manual lens. I still use my 8042q when I'm shooting critically but for run and gun, I've had no problem with the color viewfinder/manual lens. As Mike Avery stated previously, "you can see things snap into focus". It was a different story altogether when I would use the standard auto lens or 3x with the color viewfinder, it was a guessing game.

Rob Lohman
May 8th, 2002, 04:47 AM
Underscan is a real problem with the color viewfinder in my
opinion. I had it once or twice too having things in frame that
where not there on my viewfinder. Haven't had too much
troubles with focusing yet though.... Or I don't know what
sharp focus looks like :)

Aaron Koolen
May 8th, 2002, 06:08 AM
While on this topic, and being a newbie I have a question regarding B&w vs Colour viewfinder. I got to play with an expensive Sony camera the other day (Think it was a 570 or something) and it had a B&W vf. Now focussing was great but it seems to me that without colour you're losing all this information about how the scene will look. It's basically a guessing game is it not? Wouldn't a colour vf at least allow you to get a rough idea as to how the saturation, hue and all that stuff is going to come out in the final image? Am I missing something here?

For someone who will buy a camera soon and will not be able to afford an XL1s *and* a B&W viewfinder, but who want's to shoot short movies I would have thought that B&W should be kept way from?

Cheers
Aaron

Mike Avery
May 8th, 2002, 08:07 AM
I'll post this again, it didn't show up last time. My apologies if it landed in the wrong forum somewhere.

I've used black and white crt viewfinders on several professional cameras ranging from the old RCA TK76 to $75,000 Ikegamis. Most recently the Panasonic AJD 200 series.

There's no doubt they are the best choice for ease of focus.

However, you can achieve critical focus with an XL1 color LCD viewfinder and the 16X manual lens.

I find it's best achieved by using the zebra function. When you hit critical focus the zebras seem to change in appearance, (yes, "snap" into focus).

Sure, you could put a b&W viewfinder on an XL1, but by then you've spent enough to get a better camera.

Mike Avery

Guest
May 8th, 2002, 08:41 AM
I agree with you 100% Mike Avery. I feel the XL1s works just fine for me with the 16x manual lens and no other add on acessories. As you said before and I'll repeat it again, the 16x manual lens was the best investment I made in the MiniDV format besides the XL1s camera itself.

Josh Bass
May 8th, 2002, 08:58 AM
Okay, okay. . .so we do or don't think a b&w viewfinder necessary. . .being that we can use zebra bars to focus. . .and some of don't have underscan issues?

Rob Lohman
May 8th, 2002, 09:51 AM
Everyone must have underscan issues.... The viewfinder crops
more than just the TV safe area... and I even want to know what
is in there... Currently I have a laptop with me on my shoots.
That way I can directly see what signal I'm getting through
firewire.

Josh Bass
May 8th, 2002, 11:02 AM
All i have is my varizoom lcd monitor

Kai Leibrandt
May 11th, 2002, 01:45 PM
Hi all,

with respect to the underscan issue; the CVF _does_dramatically underscan. Sometime next week Chris will put a new article about 16:9 and frame mode up that I finished today which has some images to show how much is actually cut off. Until then... you'll have to wait or try it out yourself. BTW: watching the output on a TV is no good either, all TV's underscan too (hence the need for safe frames).
Best thing to check underscan is to capture some footage with a grid or testchart through your firewire - the image captured is the complete image from the CCD's.

HTH,

Kai.

Josh Bass
May 11th, 2002, 03:34 PM
But unless I know my stuff is going to reach theatrical distribution, isn't what a consumer television shows me good enough? Granted there's that portion of the population with HD TVs and such, is it really that big of an issue?

Bill Markel
May 11th, 2002, 03:45 PM
<<<-- Originally posted by SlashRules : But unless I know my stuff is going to reach theatrical distribution, isn't what a consumer television shows me good enough? Granted there's that portion of the population with HD TVs and such, is it really that big of an issue? -->>>

Slash,

If you might be doing something for distribution with Quick Time or Windows Media it may become a problem. These formats will show everything including the problem with the black bar at the bottom of the picture.

And yes, you are not alone. I was out shooting yesterday and had the same focus problem to which you referred in your original post. I thought I was doing something wrong.

Bill

Ken Tanaka
May 11th, 2002, 07:38 PM
Slash,
Indeed, normal underscan is not an issue for material targeted at standard tv viewing. Underscan, itself, is unavoidable. But, as Bill noted, streamed or digital material will show the full frame's contents.

Also, the color viewfinder's frame is, I believe, cropped closer than the underscan borders. So unless you are careful you can easily find unintended stuff creeping into the recorded frame and not discover it until you go to post.

ja135321
May 23rd, 2002, 03:03 PM
Haha,

Try going all the way wide in the 3x and you can get the lens hood in the frame.

I know you can edit the frame in post, but then if it's focus critical in post production you might have a problem.

Chris Hurd
May 23rd, 2002, 03:27 PM
I've shot extensively with the 3x lens out all the way wide and have *never* had the lens hood appear in frame. The hood which comes with the 3x is shaped differently than the hood on the standard 16x; if you use the wrong hood then I can see how this would be the problem. But as to the 3x hood appearing in the frame, that's a new one on me, I have never experienced that after much shooting all the way wide with that 3x lens.

Ken Tanaka
May 23rd, 2002, 03:37 PM
Same here. As long as the 3x hood is mounted properly it cannot possibly creeep into the frame whatsoever. That said, it is possible to mismount the hood, particularly if you're in a hurry and not paying close attention. Just make sure that the set screw slides into the lens' channel and that you lock it down.