*Camera* front focusing?

divamum

Oh boy have I had one of those days.

High on the list is that it appears my 7d is trying to misfocus a lot I noticed last week during some SP's that there were more mis-focuses than I would have expected, but I chalked it up to errors on my part and didin't worry about it.

Today, however, out shooting in the leaves, it seems that 70% of the shots are missing the focus - usually front focusing, although a few back-focused (the 50mm seemed more prone to that) - and I KNOW I was doing my job right. At least two lenses show the inconsistency, the 135 and the 50mm, both of which are usually very accurate.

How do I go about doing a bit more diagnostics on this, and is there anything simply I can/should try like cleaning contacts or something?

Ugh - this is not my idea of a fun weekend (to add insult to injury I dropped an 8g cf card while lying in the leaves, didn't realise it till later, and couldn't find it when I went back). Only consolation is that I'm discovering this BEFORE a shoot in 2 weeks, so hopefully can resolve it.


ETA: I've had the camera since May and it's worked like a champ, it hasn't been dropped or bumped that I'm aware of, and I can't think of anything I'm doing differently now than 10 days ago. Sigh.
Thanks in advance!

EATA: Could modest backlighting (in shaded woodsy area, bright light in the distant background, "overcast" light where subject and camera were situated) lead to these kinds of AF mistakes? I've just taken it outside again in slightly more contrasty light, and it's performed more typically.

Grr. Getting very frustrated today.

ziggy53

Remember that the 7D AF is "extremely" customizable. What are your AF settings?

ilbcnu

Diva I have had similiar experience with my 7d-I go back to the Quick control sceen and check all my settings. I also seem to have landed on AF point expansion as the best focus mode for me -not sure if it is what I should be using but focusing seems easier/better currently -which selection are you using?

divamum

Everything looks to be the same as usual - single point, one-shot. I switched OFF AFMA halfway through the shoot just in case there was a setting buried in there so it shouldn't be that. I'll go through everything else in the morning when I'm less fed up with it all, but so far... no indication of anything untoward.

I did have the aftermarket battery in - could power issues cause something like that? It's worked flawlessly to date, but it is the un-chipped flashpoint/Adorama battery.

ziggy53

divamum wrote: »

... I did have the aftermarket battery in - could power issues cause something like that? It's worked flawlessly to date, but it is the un-chipped flashpoint/Adorama battery.

I don't think that battery type could cause this sort of issue.

You mentioned bright lights in the background and that situation can cause the AF to stray to the back.

If the AF is working properly in other situations then I presume this is a situational problem.

divamum

Yes, but also earlier in the week doing SP's it didn't behave - camera on a tripod, stopped down to about 5.6 where I'd have expected the entire shot to be in focus. It's the inconsistency that's frustrating me at the moment.

How can I check for something like this to diagnose whether it is situational or a problem? As mentioned in earlier post, I have an e-shoot coming up in two weeks and if I need to get it fixed I want to get on with it asap.

Also... could filters cause focusing issues? Haven't had problems before, but just wondering.

As always, thanks Ziggy for the advice (and handholding)!

ziggy53

You might check the AF section to see if any dirt/lint/hairs are affecting AF performance. First check the main mirror, especially near the center of the mirror. If you have to clean the mirror be very careful not to scratch the mirror as it is a front-surface type and has little protection.

Next bring the main mirror up in clean mode and check the AF port to see if it's clean and clear. The AF port and sensor is at the bottom of the mirror box assembly. You may need a dentist type mirror to check the port and AF section.

If all of that is clear then yes, try to remove any filters and see if the problems persist.

Here is a diagram of the location of the AF sensor and port:

http://media.the-digital-picture.com/Images/Other/Canon-EOS-1D-Mark-IV-Digital-SLR-Camera/AF-Optics-Cutaway.jpg

Here is an image of one of my cameras and an arrow showing the location of the AF sensor and port:

Dan7312

Preface, I don't claim lots of expertise but these are things I've tried when I couldn't figure out why I couldn't get the focus right.

Have you tried the taking a picture of taking a newspaper taped to the wall thing? That eleminates some of other stuff like bright background.

The area the camera looks at to do focusing is bigger than the little square that appears in the view finder, so it's possible that the focusing area included leaf and something else at different distances.

What was the shutter speed? I do know that when I have tried to shoot leaves in the past a slight bit of wind makes them move but not necessarily all at the same time.

Since you are shooting on a tripod you could try focusing on a particular leaf using the live view at 10x with AF turned off, and then shooting the same leaf again with AF turned on without live view, with the focus selector on the same leaf. If there is any wind at all the 10x on the live view will be pretty tough to use, but you might have to use 5x. I've not had much luck focusing with live view at 1x though. If it's too windy for leaves pick some thing like a thicker twig. If it doesn't move in live view at 10x then it's plenty stable for a picture.

divamum wrote: »

Yes, but also earlier in the week doing SP's it didn't behave - camera on a tripod, stopped down to about 5.6 where I'd have expected the entire shot to be in focus. It's the inconsistency that's frustrating me at the moment.

How can I check for something like this to diagnose whether it is situational or a problem? As mentioned in earlier post, I have an e-shoot coming up in two weeks and if I need to get it fixed I want to get on with it asap.

Also... could filters cause focusing issues? Haven't had problems before, but just wondering.

As always, thanks Ziggy for the advice (and handholding)!

divamum

Not sure I'm to the bottom of this yet, but found some good online articles, messed with some settings (info here), and did a hard reset (info here) and tried again. I figured that the hard reset certainly couldn't hurt so nothing to lose.

Since I'm not doing "controlled testing" but using the camera in real life, I'm not sure if those made any specific difference, although the results today were indeed markedly better, with the misfocuses generally being at shallow depth of fields where I'm pretty sure I wasn't as accurate as I needed to be and/or, as Dan says, in situations where the reality of the af point is calculating from a larger area than the eye realises. Until I can try some slightly more controlled tripod shooting this week, I'm going to assume that yesterday's issues were a combination of low-contrast in dull lighting conditions. What it DOES tell me is that in those situations I really need to bump iso up so I can expose further to the right, and stick the STE2 on the camera to act as focus assist; again, it can't hurt and just might help.

For the time being, I'll say that it was, as Ziggy suggests, situational due to an unfortunate combination of sensor-tricking conditions. I'll report back on this if I figure out anything more conclusive. Main thing is that I'm a little wary of it now and will be chimping even more than usual on critical shoots!!

Michael Banks - GSP

Me Too
I have the same problem with my 7D as you do and it is currently on its way to Canon for the 2nd time in as many months for repairs. AF is all over the place. On some shoots it focuses perfectly under horrible lighting conditions and on others it misfires 70% of the time under great lighting. A recent studio portrait shoot was one of those 70% bad ones prompting me to send it in to Canon again.

I've spent a lot of time on the phone with Canon support ruling out operator error or bad settings. If you haven't already, give Canon USA support a call (1-800-828-4040). They are surprising knowledgeable and don't try to rush you. Anyway, the AF problems were happening across a wide variety of conditions and settings with no consistent pattern that AF microadjustment could correct for. I think that the 7D's AF system has bad quality control and still has some bugs to be worked out.

Here is a gallery with some examples of the problems I've been having along with acceptably sharp photos from each shoot. The beach shoot was what prompted me to send in my 7D the first time with many of the photos as out of focus as the bad one in this gallery. Canon electronically calibrated the AF assembly and, once I got it back, it focused perfectly for about a month before the percentage of bad shots started creeping up again. If you are still under warranty, Canon will do this adjustment for free (you pay shipping there). The turn around for me was about a week.

I hope things work out for you.

divamum

Ok, mine are nothing like as extreme as those you linked. I also noticed that in the worst of my mis-focuses yesterday, where eyes were soft, the shirt my daughter was wearing - with a high contrast logo on it - was often perfectly sharp, so my guess if that for whatever reason it was latching on to that instead of her eyes, despite my using single point and thinking I was aiming it exactly right. I'm still not quite sure what was going on, to be honest.

I actually purchased my 7d as a refurb from Adorama last May so if it goes back, it goes via through their warrantee; I'm going to set it up on a 'pod this week and try some more controlled testing to see if it recurs, so we'll see what happens....

Thanks for chiming in!

JimKarczewski

If you have a flash handy, try throwing it on the body to see if it changes the focusing in any way. Just disable the flash, so only the focus-assist works. I do that a lot now and get better results with my MkII thanks to the assist beam.

HelenOster

divamum wrote: »

I actually purchased my 7d as a refurb from Adorama last May so if it goes back, it goes via through their warrantee; I'm going to set it up on a 'pod this week and try some more controlled testing to see if it recurs, so we'll see what happens....

You know where I am if you need help with a return!

Matthew Saville

divamum wrote: »

...How can I check for something like this to diagnose whether it is situational or a problem?...

Hate to say it, but you need to do a "lab test". Get a tripod, and preferably a cable release, and an immobile object such as a medium sized tree trunk with plenty of detail.

I know you feel like such a clinical test will not be an accurate representation of real-world shooting, but honestly this is how you eliminate the camera from the equation. You can perform the test with and without your favorite filters, or with / without serious flare, if that gives you more confidence in the test results.

The bottom line is that if you want to find the culprit, you gotta eliminate factors. Front focusing does not magically manifest itself only when you're hand-holding, it is a consistent error that will affect the vast majority of every shot, in every condition. Front/back focusing is a very common issue though, so I'm sure that's what's up. Just diagnose the issue for sure, then start fiddling with the AF micro / fine tuning setting. Turn your in-camera sharpness way up, shoot wide open, and test each lens...


=Matt=

divamum

@Helen - thanks, if needed, I do indeed!

@Matt - oh absolutely, that's why I plan some tripod testing this weekwhen I will have the time to do it properly!