| Author | Thread |
|
|
09/18/2011 06:04:18 PM · #1 |
Sorry to be a nuisance again. It's a new problem, so I thought I should start a new thread.
Background info: My 7D was in the shop this week for a service after freezing a few times during a shoot last weekend. I got it back on Friday and have yet to establish whether or not the problem has been sorted out. (It's difficult to tell with intermittent problems.)
What's got me worried now is that the first shot I took yesterday - on tripod, with timer and mirror lock-up - was hopelessly out of focus. I changed focus points and the next few were okay. Same thing happened this morning. In the afternoon I was shooting handheld and focus was a bit hit and miss. On all occasions I was using my Sigma 18-200 IS. Now I've been aware for some time that this lens isn't behaving 100% because if I turn the camera face down, the lens will zoom in without my touching it. Today was the first time I took it seriously and when I turned the camera either face up or down I could actually see the lens extending until it was fully zoomed.
As the camera has just been serviced, I feel it is unlikely that it would suddenly develop a focus problem. I've had out of focus photos before with this lens (maybe others too) but have always assumed it to be human error. But the tripod shots should not have missed so badly (using autofocus). Just wondering if this is more likely a problem with the camera or the lens before I decide whether to contact Canon or Sigma. |
|
|
|
09/18/2011 06:10:36 PM · #2 |
Originally posted by GinaRothfels:
Sorry to be a nuisance again. It's a new problem, so I thought I should start a new thread.
Background info: My 7D was in the shop this week for a service after freezing a few times during a shoot last weekend. I got it back on Friday and have yet to establish whether or not the problem has been sorted out. (It's difficult to tell with intermittent problems.)
What's got me worried now is that the first shot I took yesterday - on tripod, with timer and mirror lock-up - was hopelessly out of focus. I changed focus points and the next few were okay. Same thing happened this morning. In the afternoon I was shooting handheld and focus was a bit hit and miss. On all occasions I was using my Sigma 18-200 IS. Now I've been aware for some time that this lens isn't behaving 100% because if I turn the camera face down, the lens will zoom in without my touching it. Today was the first time I took it seriously and when I turned the camera either face up or down I could actually see the lens extending until it was fully zoomed.
As the camera has just been serviced, I feel it is unlikely that it would suddenly develop a focus problem. I've had out of focus photos before with this lens (maybe others too) but have always assumed it to be human error. But the tripod shots should not have missed so badly (using autofocus). Just wondering if this is more likely a problem with the camera or the lens before I decide whether to contact Canon or Sigma. |
You should really post some photos to let people see and understand what's actually going on. It helps a lot. Especially when you include all the exposure info such as aperture, ISO, shutter speed, focal length etc. Also distance to subject is helpful to establish depth of field and whether your lens is may be front or back focusing. Did you try any other lenses to eliminate the camera etc.?
You lens has lens creep. Lens creep is when you hold the lens up or down and it moves under it's own weight.
Dave |
|
|
|
09/18/2011 06:24:56 PM · #3 |
I haven't had a chance to try other lenses yet, though I realise I should. (The only other lens I had with me this afternoon was Lensbaby and that doesn't help with autofocus testing :)) I'm reluctant to make any unnecessary lens changes right now as I'd like to keep my sensor clean for as long as possible, but at least one lens change will be necessary. I also thought I should post photos but my computer is rather overworked at the moment - I have Excel refuse to start earlier and had to do a system restore to get it going again. Right now I've got a full virus scan running so I don't think my computer would be too happy if I asked it to download photos from my camera as well.
I can tell you that the photos on tripod were F11, 10 sec exposure at ISO 100 with distance to subject approximately 6 feet. The handheld photos were all taken at close distance as well near both ends of the zoom range, Auto ISO and the out of focus ones were mainly with large apertures.
How common is lens creep? None of my other zoom lenses seem to have this problem. |
|
|
|
09/18/2011 06:53:50 PM · #4 |
Originally posted by GinaRothfels:
How common is lens creep? None of my other zoom lenses seem to have this problem. |
It depends a lot on the design. Some specific lens designs are very prone to it (all copies do it) others are pretty much immune. It can also increase due to usage (loosening due to wear).
|
|
|
|
09/18/2011 06:55:35 PM · #5 |
Lens creep is common enough, but not all lenses are effected by it, and some that don't exhibit it when the lens is new can loosen up over time and start to appear. It also doesn't necessarily happen across the whole focal length range. For instance, on my Canon 15-85mm lens (cost $720 dollars when I got it...so it's not cheap) the lens didn't creep when held downward, but when set to around 50mm and pointed up it would creep down a little before stopping. Some lenses have a lock in place to keep it from creeping during transport or walking around...such as my Canon 70-300mm lens. Obviously not the most desirable thing to have to deal with. Some lenses can be fixed, and some are so inherent to the design that there is nothing that can be done...it is what it is.
!0 seconds at F/11 and ISO 100 indicates that you were shooting in EXTREMELY low lit situation. That's a very long exposure IMO..even with a middle aperture and your lowest ISO setting. So it's that's the case it's also important to realize that the focus system works on a contrast basis. Your focus points are looking for a distinct difference between darker and lighter shades. In low light situation...and especially very low light situations it can be very hard for the camera to get the right focus lock.
One thing you can do to help if this is the case and it's possible (such as a controlled environment for a still life or studio shot) is to turn the lights on which will give you better contrast, focus the camera as you normal would, set the camera to manual focus, shut the lights back off and the camera will readjust the exposure for the darker scene while keeping the focus intact. You can also use a flash light to momentarily light the area your focus point in on in order to grab the focus lock. If you do keep the focus set to auto then remember not to lift your finger off the halfway position after you get the focus right and remove the flashlight otherwise your camera will try to focus again and it will be off. So if you do it that way...keep your finger down on the shutter release (halfway) turn the flashlight off and THEN push the shutter release the rest of the way.
Dave |
|
|
|
09/18/2011 07:20:17 PM · #6 |
Dave, I know those sounds bad, but it really didn't seem that dark to me. The photos were taken indoors around midday some distance away from a decent sized window. And a simple change of focus point got the correct focus. Later photos in the set look very sharp. These are conditions I work in quite often, though I think mostly I've been using my 18-55mm (non-stabilised version) for these shots lately without any problems.
I've just checked another one that was really bad - handheld, zoom probably 18mm, ISO 100, 1/50 sec at F3.5 with stabiliser on. (And yes, the stabiliser was OFF when I used the tripod.) I really can't find any part of that photo that seems to be in focus. Changing focus point got an improvement, though I can't really tell on the camera screen whether it's as good as it should be.
ETA: the lens does lock, but only at 18mm. Doesn't help much when I'm trying to shoot something high overhead at 200mm.
Message edited by author 2011-09-18 20:11:13. |
|
|
|
09/18/2011 07:21:50 PM · #7 |
| wow, you really have OCD with sensor dust... |
|
|
|
09/18/2011 07:25:17 PM · #8 |
Originally posted by mike_311:
wow, you really have OCD with sensor dust... |
Not really. But I've never been able to get my sensor clean on the 400D (possibly because of the idiot who sprayed canned air into the camera without my permission), so I'm scared to touch the sensor of my 7D. My HDR shots were looking pretty bad before I got the sensor cleaned so I'd at least like to benefit from the clean sensor for a little while. |
|
|
|
09/18/2011 08:03:33 PM · #9 |
Originally posted by GinaRothfels:
Lather photos in the set look very sharp. |
At least post the lather pics... ;-) |
|
|
|
09/18/2011 08:10:42 PM · #10 |
Originally posted by JH:
Originally posted by GinaRothfels:
Lather photos in the set look very sharp. |
At least post the lather pics... ;-) |
lather? Oops I just found the typo. Will fix.
At the moment all the pics are still in the camera. I'm still trying to get computer problems sorted out. Microsoft Security Essentials says "Preliminary scan results show malicious or potentially unwanted software might exist on you system". I'm still waiting for the scan to finish to find out what they are. It's well past midnight and the scan has been running for nearly 5 hours.
I've had a real bad week with technology:( |
|
|
|
09/18/2011 08:54:31 PM · #11 |
Originally posted by GinaRothfels:
I've had a real bad week with technology:( |
Well I'm sitting here battling with video file formats and ISO files at 2am.... Is there any such thing as a *good* week with technology? |
|
|
|
09/18/2011 09:07:26 PM · #12 |
Originally posted by JH:
Originally posted by GinaRothfels:
I've had a real bad week with technology:( |
Well I'm sitting here battling with video file formats and ISO files at 2am.... Is there any such thing as a *good* week with technology? |
I know the feeling. Sometimes I think I'd like to go back in time to when we didn't have to put up with all that. This week more so than most. |
|
|
|
09/18/2011 09:40:59 PM · #13 |
| well if we went back to when we didn't have all the technology there would defiantly be more jobs out there for people. |
|
|
|
09/18/2011 10:05:51 PM · #14 |
Originally posted by o2bskating:
well if we went back to when we didn't have all the technology there would defiantly be more jobs out there for people. |
Too true. |
|
|
|
09/18/2011 10:46:21 PM · #15 |
Take one issue at a time ! Focus issue, dust, lens creep....all that will drive anyone nuts !
I'd say if your sensor has goop on it, and you say that changing focus points helps...then the sensor could have goop in some spots ! That would be easy to test with a tripod and a focus card.
As for focus, I've had doubts about my 80-200 over the past few weeks. After testing I've found that the lens likely DOES NOT have any issues. I've recently been using my DOF preview with my manual focus and have gotten much better results !
Show us some shots !
|
|
|
|
09/19/2011 07:24:08 AM · #16 |
 kenskid, the sensor doesn't have goop on it - it's just been for a service and the sensor was cleaned. The sensor problem is with my other camera. The lens creep is on the lens I have been using since I discovered the focus issue, I mentioned it because I thought the two problems might be connected.
The focus issue is using auto-focus, not manual. What worries me is that some photos are fine while others are way off the mark, so it's not a front or rear focusing issue.
I know I should show shots but my most urgent issue right now is something which infected my computer, which has made it impossible for me to access Microsoft Excel. A system restore fixed it for a while, but now it's messed up again and system restore keeps coming up with error messages. Microsoft Security Essentials cleared the threat, but I can't get at my business files! |
|
|
|
09/19/2011 11:39:50 AM · #17 |
Hmmm...so on auto focus you may get a good clear shot and then take another at the same focus point and get TOTAL BLUR? On the ones that are out of focus...is ANYTHING in focus?
Originally posted by GinaRothfels:
kenskid, the sensor doesn't have goop on it - it's just been for a service and the sensor was cleaned. The sensor problem is with my other camera. The lens creep is on the lens I have been using since I discovered the focus issue, I mentioned it because I thought the two problems might be connected.
The focus issue is using auto-focus, not manual. What worries me is that some photos are fine while others are way off the mark, so it's not a front or rear focusing issue.
I know I should show shots but my most urgent issue right now is something which infected my computer, which has made it impossible for me to access Microsoft Excel. A system restore fixed it for a while, but now it's messed up again and system restore keeps coming up with error messages. Microsoft Security Essentials cleared the threat, but I can't get at my business files! |
|
|
|
|
09/19/2011 01:29:31 PM · #18 |
Originally posted by GinaRothfels:
kenskid, the sensor doesn't have goop on it - it's just been for a service and the sensor was cleaned. The sensor problem is with my other camera. The lens creep is on the lens I have been using since I discovered the focus issue, I mentioned it because I thought the two problems might be connected.
The focus issue is using auto-focus, not manual. What worries me is that some photos are fine while others are way off the mark, so it's not a front or rear focusing issue.
I know I should show shots but my most urgent issue right now is something which infected my computer, which has made it impossible for me to access Microsoft Excel. A system restore fixed it for a while, but now it's messed up again and system restore keeps coming up with error messages. Microsoft Security Essentials cleared the threat, but I can't get at my business files! |
Almost sounds like Malware. Try out Malwarebytes, might have to be run in safe mode, been a long while since i've had to use it. |
|
|
|
09/19/2011 04:44:39 PM · #19 |
kenskid, close but not quite. I would get a total blur, then move the focus point without moving anything else and then get a clear shot.
 JRoberts1983, Microsoft Security Essentials found something which it removed - Exploit:Java/CVE-2010-0840.IU But apparently Microsoft Office had got totally corrupted - I don't know whether there was a connection between the two. For some reason System Restore very rarely works on my computer, so after hours of struggle and internet searches, finding many references to similar problems, but no solution that worked for me, we were forced to phone Microsoft. It took a long time with them taking shared control of my computer, but they finally managed to remove Office and re-install it. Right now everything seems to be okay but my whole day has been wasted.
So now, with a (hopefully) healthy computer, it's time to download photos from my camera and see if I can get the focus issue sorted out. |
|
|
|
09/19/2011 05:35:32 PM · #20 |
| 7D?? what setting are you using? I have found that carrying the camera on your right shoulder can cause the setting to change on the dial. I don't know if Canon are aware, but on more than one occasion my camera has moved from P mode to A or TV mode and this affects your shots if you haven't noticed. A design fault that Canon need to modify. |
|
|
|
09/19/2011 05:41:30 PM · #21 |
Originally posted by SteveJ:
7D?? what setting are you using? I have found that carrying the camera on your right shoulder can cause the setting to change on the dial. I don't know if Canon are aware, but on more than one occasion my camera has moved from P mode to A or TV mode and this affects your shots if you haven't noticed. A design fault that Canon need to modify. |
Well, if you want to pay for it you can be the proud owner of a mode dial lock from Canon. Personally, I don't have that problem because I never shoot in "P" mode. :P Sorry, couldn't resist. Obviously it would move in any mode under the right conditions, but I really never had it happen to me so at this point I personally wouldn't spend the money.
Here is the link for the Mode Dial Lock for the Canon 7D and Canon 5D MkII.
Dave |
|
|
|
09/19/2011 05:51:05 PM · #22 |
Originally posted by DCNUTTER:
Originally posted by SteveJ:
7D?? what setting are you using? I have found that carrying the camera on your right shoulder can cause the setting to change on the dial. I don't know if Canon are aware, but on more than one occasion my camera has moved from P mode to A or TV mode and this affects your shots if you haven't noticed. A design fault that Canon need to modify. |
Well, if you want to pay for it you can be the proud owner of a mode dial lock from Canon. Personally, I don't have that problem because I never shoot in "P" mode. :P Sorry, couldn't resist. Obviously it would move in any mode under the right conditions, but I really never had it happen to me so at this point I personally wouldn't spend the money.
Here is the link for the Mode Dial Lock for the Canon 7D and Canon 5D MkII.
Dave |
Thanks Dave:)
I used P mode as an example? What I was trying to get across is that just by carrying your camera, on its strap, over your right shoulder...it can change the mode. This is something that never happened with my Nikons, and never happened with my older Canon cameras, the 300D and two 30Ds. But I can live with it, but it could have serious implications if someone is taking once in a lifetime photos!
ETA: As to the link you provided...Canon are admitting that there is a design problem and if you want to pay for the fix, you can have it!! Perhaps they should have fitted this lock free of charge as it is their problem to begin with!
Message edited by author 2011-09-19 17:53:41. |
|
|
|
09/19/2011 06:06:36 PM · #23 |
| Yes, I'm well aware of the mode dial slipping, but it isn't the issue here. I will have some crops up shortly to show what's happening. |
|
|
|
09/19/2011 06:33:26 PM · #24 |
Okay, I've finally got some images up. They are 100% crops of an area including the focal point, which is marked with a red rectangle by DPP. Settings and focal lengths given in image details.
First two taken on tripod using mirror lock-up using the same settings in the same light. And yes, both were taken with stabliser switched OFF.
The good  and the VERY bad 
Next a very bad one taken outdoors in fairly decent light, handheld with stabiliser on, zoom at full wide angle.
And a surprisingly good one taken in very poor light indoors, handheld with stabiliser on and zoomed in quite a lot. This is detail of a statue several times my height.
 |
|
|
|
09/19/2011 06:48:13 PM · #25 |
Gina, your first "very bad" example is for sure camera shake. I know it's on-tripod, but it's smeared in a nearly-vertical direction. The second bad one does look like a case of missed focus.
|
|
Home -
Challenges -
Community -
League -
Photos -
Cameras -
Lenses -
Learn -
Prints! -
Help -
Terms of Use -
Privacy -
Top ^
DPChallenge, and website content and design, Copyright © 2001-2024 Challenging Technologies, LLC.
All digital photo copyrights belong to the photographers and may not be used without permission.
Current Server Time: 04/23/2024 09:25:07 PM EDT.
