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FORUMS Canon Cameras, Lenses & Accessories Canon EOS Digital Cameras 
Thread started 09 Feb 2011 (Wednesday) 20:48
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YAAFT (Yet Another Auto Focus Thread)

 
ppmax
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Feb 09, 2011 20:48 |  #1

Hello--

I think this is my first post...Hello ;)

I recently bought a 7D as an upgrade to a 40D. I have 3 lenses:


  1. Canon EF50mm f/1.4 USM
  2. Tokina 11-16mm f/2.8
  3. Canon 24-105mm f/4 USM IS


I've taken sharp/in focus pictures with each of these lenses with my 40D (along with some OOF shots too!) In fact, I know the nifty fifty has a slight front focus issue at wide open f-stops.

Before purchasing my 7D I thoroughly researched this camera and was aware of the "focus issues" reported on just about every forum that caters to Canon DSLR owners. I am aware that some of these issues are user error, but that there appear to be legitimate problems among a select few that have been repaired via adjustments at Canon service centers.

Right after receiving my new baby I set out to determine if I had issues (user error or otherwise). I've read the manual and believe I have a firm grasp on the different AF modes. One thing that is clear to me: when the AF gets it right, this is an incredible camera.

I've conducted several tests and believe:
  • Im doing something wrong; or...
  • I have a "real" AF issue; or...
  • I have a expectations that are not aligned with reality; or...
  • I don't have a firm grasp of the different AF modes and how they work


I feel that I am a reasonably skilled photographer, and will post some samples of past work if asked. Using the post "-=What to do if you suspect a focus problem with your DSLR=-" as a guide, I'm submitting myself to critique, suggestions, and hopefully corrective actions/advice about how to "fix" these issues.

Conclusions:
  • My 7D can auto focus, but in this limited experiment and some handheld walkaround shots, the AF was somewhat unpredictable. I varied lighting to see if that had some effect, and also varied subject matter for contrast, etc.
  • I also tried some handheld shots in bright conditions with different subjects with the same unpredictable results
  • I tried different lenses, with similar results
  • Wow, that nifty fifty has some CA at wide open...
  • In most instances, my 40D would have nailed these shots easily
  • Some images, taken right after each other, grab/miss focus
  • I probably need to send this body in for some adjustments...but what do I tell them so they fix it?


Here is goes:
1. Please post some sample shots that show the problem, with Exif information intact or included. Linking to full sized images is useful
Here are some images. Each image pair is a screencapture of the focus points as displayed in Aperture and a 100% crop of the relevant area. Each frame was captured using a tripod, flash, mirror lockup, and a wired trigger. All shots were taken at ISO 100 or ISO 200. Looking back on these tests, I know that the ambient lighting was a bit low, which required the flash to fire a focus beam every now and then. Nonetheless, I received a focus lock beep before each shot was taken, and verified that the focus light through the viewfinder. Each shot was taken using manual (center) AF selection point.
http://homepage.mac.co​m …/Canon_7D_AutoF​ocus_Test/ (external link)

2. Verify the camera/lens can in fact focus under good conditions first.
Done. I know these lenses and have shot them with my 40D. As stated above, the 50 has slight front focus, but nowhere near as bad as some of the images show.

b. Verify adequate shutter speed – suggest a minimum of 1/(2 times focal length) for troubleshooting, to keep it simple use 1/1000 or faster, or use a tripod/stationary camera with remote release or self timer
All shots, and some other tests not posted, were taken with fast shutter or a tripod. All shots posted above were with camera on tripod with mirror lockup and remote trigger.

c. Use a reasonable depth of field
All of these shots were taken wide open with the 50. Typical exposures were ISO 100, f1.4, at 1/25.

d. Verify the lens switch is set to AF not MF, IS is off if shooting on tripode.
AF was on, tripod used.

f. If AF seems to be causing problems try manual focus, Live View is easiest for this if your camera has it. Verify you can focus sharply in manual.
Manual focus works like a charm...I've confirmed it is slower than AF ;)

g. If it's the camera that is in question verify the problem with a second lens if possible, if the lens is the question try a different camera if you can.
Done; AF issues when shooting with prime, wide, and zoom lenses.

h. If with the above there seems to be consistent problems there may be front or back focusing, testing for this is well described here, member Teamspeed has a free lens adjustment tool to aid focus adjustment, described and available here
Before getting the 7D I tested these lenses and they appear pretty good. One indication that something strange is happening is that these issues are seemingly "random" where I'll achieve focus in one shot then miss it in another.

Lastly, I'd like help/peer review "concluding" that this new body needs work...soon, because I already miss this thing :cry:

Any comments, questions, or critiques very welcome!
Thanks again,
PP

Canon 1DX Mark II, EF 100-400 f/4.5-5.6 IS USM Mark II, EF 70-200mm f/4L IS USM, EF 24-105mm f/4L IS USM, EF 50mm f/1.4
Rokinon 85mm f/1.4 AS IF, 14mm f/2.8 ED AS IF UMC

  
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eddyav
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Feb 09, 2011 21:20 |  #2

One thing that is clear to me: when the AF gets it right, this is an incredible camera.
This is what I went thru,also came from a 40D,the 7D is not as forgiving.The learning curve took a little time,the focus selection is intimidating.I went to spot focus and did some MA on my lenses,now all is good.Take some time before you send it in,check your focus using the MA to fine tune the lenses ( I used rocks on the lawn,brick walls, chain-link fences,etc... at about 45% angels till I was satisfied)most of my lenses needed a -2 worst one a-6,not much but it sure made a difference.You can always reset the MA if you need to,it might help.There are several links to MAing if you look for them,I tried some but went the "real world" option and got more consistent results.The 7D is a very fine camera when it works right,it can be frustrating at times tho.


7D (gripped),Tokina 12-24 4.0,Canons;24-70L 2.8,50 1.8mk1,70-200L 4.0 IS,300L 4.0 IS,400L 5.6.,TC 1.4II Speedlights:580EXII,22​0SX-2 AB 800 w/ stands,monopods,tripod​s,bags,filters,etc...

  
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ppmax
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Feb 09, 2011 22:26 |  #3

Thanks for the reply eddyav.

A question about your experience: was your AF "unpredictable" prior to dialing in your lenses, or was it consistently OOF?

All of the images were single AF point, but I did do some spot AF and it didnt seem to help. I'll try some MA as you suggest.

What's strange is that just walking around the house tonight (single point AF) shooting with the wireless flash (430EX) in low-light (a new experience for me), the AF was spot on in the majority of my shots. Granted I was using flash to assist AF, the flash AF assist fired in many of the test shots I took last night as well.

I definitely see the promise of this body!


Canon 1DX Mark II, EF 100-400 f/4.5-5.6 IS USM Mark II, EF 70-200mm f/4L IS USM, EF 24-105mm f/4L IS USM, EF 50mm f/1.4
Rokinon 85mm f/1.4 AS IF, 14mm f/2.8 ED AS IF UMC

  
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eddyav
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348 posts
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Location: Muskegon,MI
     
Feb 09, 2011 22:47 |  #4

If you are getting spot on results,I suggest that you pay attention to what you did.I was getting mixed results and in time got it sorted out.There are just so many different focus options (including in the menu)that will cause,basically,user error.The system is complex,I'm still learning it,but I found that 99% of the time I had not done something right and learned from it.I was worried about all the bad rap that I read on the forums also,but also saw that there was a lot of user error behind most of the posts.Take your time to learn the camera,there is a sticky-"what to check if you have focus issues"(something along that line) that might help you.Hopefully it's you not the camera,time will tell.Edit-found link-https://photography-on-the.net/forum/showthre​ad.php?t=857871


7D (gripped),Tokina 12-24 4.0,Canons;24-70L 2.8,50 1.8mk1,70-200L 4.0 IS,300L 4.0 IS,400L 5.6.,TC 1.4II Speedlights:580EXII,22​0SX-2 AB 800 w/ stands,monopods,tripod​s,bags,filters,etc...

  
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eddyav
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Feb 09, 2011 22:49 |  #5

Oh,Welcome to the forum,it's a great place to learn.


7D (gripped),Tokina 12-24 4.0,Canons;24-70L 2.8,50 1.8mk1,70-200L 4.0 IS,300L 4.0 IS,400L 5.6.,TC 1.4II Speedlights:580EXII,22​0SX-2 AB 800 w/ stands,monopods,tripod​s,bags,filters,etc...

  
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tonylong
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Feb 09, 2011 23:52 |  #6

Well, you mentioned the 50 front-focusing wide open and that's what I see happening in your shots, at least in ones you can actually tell. The ones stopped down appeared to focus fine. The test chart in the beginning looks to be front focusing.

So, the 7D has MA (Manual Focus Adjustment), right? I'd give that a shot on the 50 and see if you can get a consistent set that way. Doing MA on zooms is a bit tricky 'cause you can only do it at one focal length, but if you can get it working on the 50 you will at least have some verification.


Tony
Two Canon cameras (5DC, 30D), three Canon lenses (24-105, 100-400, 100mm macro)
Tony Long Photos on PBase (external link)
Wildlife project pics here (external link), Biking Photog shoots here (external link), "Suburbia" project here (external link)! Mount St. Helens, Mount Hood pics here (external link)

  
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jaycky
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Feb 10, 2011 01:03 |  #7

Tokina 11-16mm f/2.8

this is all i seen in your thread sorry you a lucky guy i want that lens almost went out the door one day a few months ago to buy new but stopped myself still want it


Depending on where the camera goes back i am sure you have read after canon techs get thru with it the camera could be af void issues meaning its going back again half its warranty could end up on a techs bench...
Loads of settings to look at and play with as well out of the camera IMO PP work to bring the image to its fullest...


5DM2 /grip Lots Of L's
measurbating f-stops
http://www.flickr.com/​photos/52633882@N07/ (external link)
http://about.me/jbmpho​tos (external link)
http://photobyfish.tum​blr.com/archive (external link)

  
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ppmax
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Feb 10, 2011 08:10 as a reply to  @ jaycky's post |  #8

Thanks again for the replies and suggestions. I really appreciate the tone on these boards ;)

If you are getting spot on results,I suggest that you pay attention to what you did.

and

Take your time to learn the camera,there is a sticky-"what to check if you have focus issues"(something along that line) that might help you

QFT. Im trying to be scientific about this--to record my process, conditions, etc while assessing this camera. Regarding the sticky thread about focusing issues: I consulted that before posting this thread; all the bold parts in my OP were recommendations from that thread.

Well, you mentioned the 50 front-focusing wide open and that's what I see happening in your shots, at least in ones you can actually tell

Yes--the front focus on my fifty is a "known known" ...but the *amount* of front focus in some test shots seems to exceed the amount that the lens is out...the strange thing is that it seems to vary. I'll be doing some other controlled tests using my 24-105L f/4 USM IS and will see what happens.

Tokina 11-16mm f/2.8

this is all i seen in your thread sorry you a lucky guy i want that lens

I love this lens--so great for indoor shots (family, events, etc) with a flash. I have some great landscapes it helped produce, too. I love how wide it is on a crop frame.

PP


Canon 1DX Mark II, EF 100-400 f/4.5-5.6 IS USM Mark II, EF 70-200mm f/4L IS USM, EF 24-105mm f/4L IS USM, EF 50mm f/1.4
Rokinon 85mm f/1.4 AS IF, 14mm f/2.8 ED AS IF UMC

  
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eddyav
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Feb 10, 2011 13:25 |  #9

Do you,by chance have a UV filter on your lenses,if so take it off,they (some) are known to cause issues also.I'm trying to help and eliminate things.You might try using spot focus (center) for awhile (it's the most accurate),shoot in AV mode,wide open f stop,one shot,on contrasty targets at various distances in good light with a fast shutter speed (3x focal length,for this test).See then if your pics are coming out consistent,it will help to figure if you have to MA that lens.Different lighting has also caused problems for some reason.


7D (gripped),Tokina 12-24 4.0,Canons;24-70L 2.8,50 1.8mk1,70-200L 4.0 IS,300L 4.0 IS,400L 5.6.,TC 1.4II Speedlights:580EXII,22​0SX-2 AB 800 w/ stands,monopods,tripod​s,bags,filters,etc...

  
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eddyav
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Feb 10, 2011 13:50 |  #10

I just re-read your 1st post and noticed that in (C) you used 1/25th second on a 50mm which would be on the slow side and motion blur can happen.The 7D needs a real fast shutter speed,it will show the slightest error-(due to the 18MP sensor) it's a nice camera,but not a forgiving camera.


7D (gripped),Tokina 12-24 4.0,Canons;24-70L 2.8,50 1.8mk1,70-200L 4.0 IS,300L 4.0 IS,400L 5.6.,TC 1.4II Speedlights:580EXII,22​0SX-2 AB 800 w/ stands,monopods,tripod​s,bags,filters,etc...

  
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jaycky
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Feb 10, 2011 15:22 |  #11

^ yea try a tripod just for a test


5DM2 /grip Lots Of L's
measurbating f-stops
http://www.flickr.com/​photos/52633882@N07/ (external link)
http://about.me/jbmpho​tos (external link)
http://photobyfish.tum​blr.com/archive (external link)

  
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Crafty
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Feb 10, 2011 15:36 |  #12

b. Verify adequate shutter speed – suggest a minimum of 1/(2 times focal length) for troubleshooting, to keep it simple use 1/1000 or faster, or use a tripod/stationary camera with remote release or self timer

All shots, and some other tests not posted, were taken with fast shutter or a tripod. All shots posted above were with camera on tripod with mirror lockup and remote trigger.

c. Use a reasonable depth of field
All of these shots were taken wide open with the 50. Typical exposures were ISO 100, f1.4, at 1/25.

[/QUOTE]

These two statements contradict each other.


flickr (external link)

  
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ppmax
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Feb 10, 2011 18:26 |  #13

Crafty wrote in post #11817327 (external link)
b. Verify adequate shutter speed – suggest a minimum of 1/(2 times focal length) for troubleshooting, to keep it simple use 1/1000 or faster, or use a tripod/stationary camera with remote release or self timer

All shots, and some other tests not posted, were taken with fast shutter or a tripod. All shots posted above were with camera on tripod with mirror lockup and remote trigger.

c. Use a reasonable depth of field
All of these shots were taken wide open with the 50. Typical exposures were ISO 100, f1.4, at 1/25.



These two statements contradict each other.

Good catch. I'm pretty bleary-eyed after work. Here's the clarification:
Some pics were taken hand-held, with a fast shutter, typically above 1/500 in bright conditions.

The pictures posted in the link above were all shot on a tripod with a shutter of significantly longer exposures--typically around 1/25. The tripod was used to stabilize the camera with these long(er) exposures and eliminate blur from camera movement.

In addition, contrary to point C above, I did not use a reasonable depth of field. In fact I shot with the minimum depth of field possible. My reason for doing this was to test for focus *accuracy.* In other words, if I pick a subject, and line up an AF point on it, I want that point to be in focus.

Any feedback about the images themselves? there were a couple that I posted that were "way out." I'm wondering if that is expected in low-light, low contrast focus points?

Thanks much
PP


Canon 1DX Mark II, EF 100-400 f/4.5-5.6 IS USM Mark II, EF 70-200mm f/4L IS USM, EF 24-105mm f/4L IS USM, EF 50mm f/1.4
Rokinon 85mm f/1.4 AS IF, 14mm f/2.8 ED AS IF UMC

  
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Crafty
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Feb 11, 2011 02:34 |  #14

was IS turned off on the lens (if it has it)


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ppmax
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Feb 11, 2011 06:59 |  #15

There was no IS; all the samples I took were from the Canon 50mm which has no IS.

After reading a couple other long threads about focus issues, it seems that the "real problems" that bad 7D's may have are:
* Inconsistent AF focus (for still sots)
* "Nothing in focus" (e.g. not a front/back focus issue...there's just no focus)
* Strange AF performance after turning the camera on/off (e.g. AF wont work, then will work after a "reboot")

I realize folks here on these boards have probably seen a million "7D/AF problem" threads...I'm just looking for a little confirmation and advice. Im honest enough to acknowledge user error if that's it, but Im also experienced enough to know how to test and isolate camera related issues. My gut is telling me that if I can't get consistent focus using a single AF point (not spot) on a stationary object when the camera is on a tripod, something is wrong with the camera...

thx much--
PP


Canon 1DX Mark II, EF 100-400 f/4.5-5.6 IS USM Mark II, EF 70-200mm f/4L IS USM, EF 24-105mm f/4L IS USM, EF 50mm f/1.4
Rokinon 85mm f/1.4 AS IF, 14mm f/2.8 ED AS IF UMC

  
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YAAFT (Yet Another Auto Focus Thread)
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