XL1 / XL1S focus hunting backfocus problems

[Jeff Donald]

This so called, focus issue, has been covered very heavily here in the past do a search of XL1 and focus, and you find numerous threads. This should help you get started

[Dean Sensui]

I won't go into technical details but just relate that I had a problem with my XL1s not maintaining proper focus throughout the zoom range.

Despite keeping everything on manual, it would shift its point of focus during a slow zoom-in even though I'd zoomed earlier in to get critical focus.

I finally got the 16x manual lens and focus has stopped being an issue ever since.

And I haven't missed much of the features of the stock 16x lens except for the stock lens' ability to do a slower zoom than the manual 16x.

Dean Sensui
Base Two Productions.

[Nathan Gifford]

Yes you will need to read some of the threads to resolve your problem. Don't forget that some of the issues may be related to changes in depth-of-field.

The high-resolution viewfinder (monochrome) does not improve focus, BUT, it does make it easier to focus the system.

[Edris Kamali]

Thank you all for your quick response. I am sure it will help me a lot and I will let you know of the result as soon as I try all of your suggestions. Once agian thank for your time and it is realy appreciated. I still looking forward to hear more from you.

Edris Kamali

[Scott Reus]

Okay, I've read every thread on focus problems w/ the camera, but I haven't seen this one. PLEASE HELP!

I'm shooting a movie and one of the shots requires my actor to lay still for about 40 minutes while the sun sets behind him (to be played much faster, of course). The camera is immobile and everything is MANUAL (triple checked). Shooting w/ the controversial 16x servo.....

With nobody touching the camera or even thinking about it, the focus COMPLETELY changes from the subject (about three feet away) to the salt on the UV filter (Grrrrr)- AND THEN CHANGES BACK about ten minutes later- AND THEN starts completely freaking out and falls in and out at incredible speeds! WHAT THE HECK IS GOING ON!! My exposure was f/10 @ 250. Camera stabilizer was on, ND filter OFF.

From what I read, this doesn't sound like a backfocus problem????

I come from a background in still photography where manual MEANS MANUAL. This shot takes forever and is hard on everybody- I CAN'T HAVE MY CAMERA FALLING OUT OF FOCUS ON ITS OWN FREE WILL!!!!!

please advise, thank you!


www.vpointfilms.com

[Rob Lohman]

I'm not sure if I have an explanation for it. It might just be
something it wrong with the camera, of course. I would at least
not use the stabilizer (not that it should create such problems,
but better safe than sorry) since you don't need it anyway.

Anyone have a better idea?

[Scott Reus]

thanks rob,

i have read that on a couple posts - "turning the stabilizer off" as a possible solution to focusing problems - i'm not sure i understand how this effects the focus?

and i do need it, ideally, as i walk 360 degrees around him with it handheld and then set it down softly in the sand in front of him- so i would like to use the stabilizer if at all possible...

thx rob.

[Scott Reus]

a thought...

could it have something to do with pointing the camera in the direction of the sun?? does a lot of direct sunlight into the lens screw it up somehow, causing it to not focus properly??

will using the time lapse feature on the camera possibly remedy this??

help!!! we're reshooting this saturday and i don't want my team's morale to drop because of another botched shoot due to camera malfunction... any thoughts are MUCH appreciated!!!!

[Ken Tanaka]

Scott,
This same issue comes up several times each year. The lens is probably not really in manual focus mode. Remember, there are two exclusive types of "manual" on the camera: "M" mode exposure control and Manual Focus (switched via the button on the lens). "MF" must show in your viewfinder to verify the focus mode.

If MF is truly engaged and verified in the viewfinder and wandering still occurs I suggest turning the camera off, removing BOTH batteries, dismounting the lens and -carefully- cleaning those electronic contacts on the mount. It's possible that the electrical communication between lens and body are being corrupted and/or the camera needs to be reset (by removing the batteries for 10 min or so).

One other suggestion, perhaps related to your problem: don't use shutter speed to control exposure. I noticed you're shooting a 1/250, presumably to control exposure. Unless you're trying to achieve a specific visual effect by using a fast shutter speed leave it at 1/60 and control your exposure with your iris and neutral density filtration (internal and external if required).

Good luck.

[Scott Reus]

i am almost 100% certain it was in both Manual modes, but i will be extra careful that the MF switch on the lens is all the way over in the future... if it is just barely not locked into the MF position, could it cause problems like this?

videography is relatively new to me, so please excuse my ignorance, but i never new to shoot (almost i assume) exclusively at 1/60. what exactly does this do for me? if there are tons of posts on this just point me to one of them... but how then do i control my DOF if the shutter speed is constant? what if my subject is moving quickly? what if i'm zoomed all the way in on my telephoto? still 1/60? the general rule for still photo is 1/focal length to eliminate camera shake and capture still motion- is this out the window?

ah- one last thing- what's the best way to clean the contacts? alcohol and a q-tip??

THANK YOU KEN!

[Ken Tanaka]

Originally posted by Scott Reus :if it is just barely not locked into the MF position, could it cause problems like this?

When it comes to electromechanical gear anything is possible. But if the MF indicator appears in the viewfinder, the camera at least thinks that the lens is in manual focus.

videography is relatively new to me, so please excuse my ignorance, but i never new to shoot (almost i assume) exclusively at 1/60. what exactly does this do for me? if there are tons of posts on this just point me to one of them... but how then do i control my DOF if the shutter speed is constant? what if my subject is moving quickly? what if i'm zoomed all the way in on my telephoto? still 1/60? the general rule for still photo is 1/focal length to eliminate camera shake and capture still motion- is this out the window?

1/60 sec is the native shutter speed for NTSC video. Remember, shutter speed on video cameras is not the same property as it is on film cameras; there is no shutter on a video camera. This camera always records at 30 frames/sec. Shutter speed is essentially a CCD sampling frequency. Changing the shutter speed on a video camera has other effects on the image, best exhibited by experimentation. Bottom line on this: on many bright subjects you can raise your shutter speed to around 1/100 without too much apparent affect. Beyond that you will notice a difference in image. As a rule, act as if the camera had no shutter speed other than 1/60 and control your exposure as I noted above.

Re: DOF, on your XL1s the iris and lens zoom are the key determinants of DOF. (Search for DOF as we have thousands of posts on this subject.) Bottom line: with a 1/3" CCD camera you have relatively limited ability to control DOF. Move the camera back and zoom-in to get an apparent shallower DOF (although with the side effect of flattening your primary target).

One other observation: be sure the camera does not become overheated while shooting 40 mins. of sunset. Very unusual phenomena can occur to hot electronic equipment.

I would suggest you do some experimentation before your next official shoot.

ah- one last thing- what's the best way to clean the contacts? alcohol and a q-tip??

Use denatured alcohol and DO NOT to use a cotton swab. Use a foam swab designed for cleaning electronic components to avoid fiber residue.

[Scott Reus]

thanks ken, i will take all of that into consideration and do some experiments before the next shoot.

this site is such a great resource- thanks all!

[Adam Burtle]

Scott-- i've run into this problem on both of the XL1's i've owned. between 2 XL1S's and 3 different 16x IIS auto lenses, the cameras would (occasionally) lose focus, even though set to manual focus, on M mode.

It seemed to happen more in low light coditions.. but I know on several occasions (maybe 1/3 of them in bright light), we would set the camera(s) for fixed focal length, assume we were gathering a bunch of good footage while just rolling between takes/etc.. and upon review the camera had lost focus halfway through or whenever, despite not being touched. I attribute this to the XL1S 16x IIs lens being a servo autofocus. With a TRUE manual focus lens, this shouldnt ever happen, obviously.

My suggestion would be to try and shoot another 40 minute sequence (without actors) after cleaning contacts, etc. If it still does it.. then you'll have to shoot the 40 minute scene with a monitor/viewfinder, and be ready to snap back the focus anytime it loses it. Luckily, i would think that would work, since if you're shooting to compress a 40 minute sequence into a few mins/seconds.. then if it loses focus for even 10 seconds before you refocus, that should noyl be fractions of a second in the final sequence (and with all the other jutter and motion in sped up footage i doubt anyone would notice).

[Scott Reus]

glad to hear i'm not alone on this one...

good advise, adam, thanks. i'll hook up my monitor next time and won't think to walk away from the camera again... what a bummer about that lens, eh?! i must say i am dissappointed. like many of the posts on this forum say, i love the stabilization- hate the quarky focussing issues. just seems like a no-brainer to leave manual, manual- especially for a product like the XL1s and especially from a company like canon! live and learn....

one of these day's i'll buy the 16x manual

many thanks. good thoughts....

[Rob Lohman]

I'm wondering if the lens is maybe calibrating itself every now
and then? Not even sure if this makes sense or is possible. But
it's a thought that entered my mind (a bit like non A/V harddisks
calibrating for temperature changes). It would be silly if it did this
whilst recording, ofcourse.

Adam's suggestion is good. And even if a frame does end up
visible you can always cut that one frame out in the end file and
no-one will miss it that way either.