Author Topic: Canon T2i/550d focusing issue (Read 49877 times)

pet_chia · « **on:** April 12, 2010, 20:03 »

So I got one of these cameras after all, and I'm extremely happy with it. My acceptance rate went to 100% except for a couple of random quibbles about "overall composition could be improved". Whatever.

Everything about the camera works great (still photos, not trying videos yet) but one problem has been happening consistently. Shooting about 15-20 feet (5-6 meters) away from from a standing subject with a 50mm lens (around 85mm effective with APS sensor) at f/8 I find it almost impossible to get the camera to focus on the subject's face in full-length shots - especially if they are holding anything in front of them like a camera, football etc.

There are 9 autofocus points. I use the menu/buttons to switch from "camera decides which zone to autofocus" to manually select the autofocus point, picking the point nearest the subject's face. I tilt the camera slightly to place the point over the face, hold down the button halfway and it locks. Then I quickly recompose and shoot, before the subject moves. But the focus is virtually never on the face, but always somewhat forward, in the region of the object they are holding (maybe 6 inches in front).

Do you think that the camera is basically overriding my selection of the focus point and trying to compromise between the area of the image under the selected point, but still taking data from some of the other points? I can see how in amateur shooting this might help save someone's vacation shots, but when I absolutely must have the eyes and teeth "tack sharp" at 100% it's very annoying.

I'm sure that better cameras have more sophisticated focusing, but for now I would like to get my $1000 worth of photos out of this baby if at all possible.

If there isn't a way to configure or trick the camera's computer then I guess I'll have to switch to manual focus on a tripod or monopod and try to discourage the model from moving too much. Or is that how most people shoot standing models in the studio anyways?

Or maybe switching to f/11 and cranking up the lights would be sufficient ...

madelaide · « **Reply #1 on:** April 12, 2010, 20:41 »

Check if your camera is set for Ai servo. I rarely manage to make it work, it goes find some place else to focus.

pet_chia · « **Reply #2 on:** April 12, 2010, 21:03 »

Quote from: madelaide on April 12, 2010, 20:41

Check if your camera is set for Ai servo. I rarely manage to make it work, it goes find some place else to focus.

It's set to "ONE SHOT" but behaving as if it's on "AI FOCUS" where it will lock focus on the point you select but automatically switch to "AI SERVO" if it detects movement.

Another possibility is that the "farthest out" autofocus point is not really where it says it is. Maybe it's not really under that little square in the viewfinder but somewhere closer to the center. I think I can overcome this by only using the center autofocus point. That should work except it will be a wider swing of the camera afterward to recompose.

I'd better do some more experimenting with blocks on a table and find out what's going on ...

pet_chia · « **Reply #3 on:** April 12, 2010, 22:06 »

OK, after some tabletop tests it seems that the "ONE SHOT" mode is reliable. The focus takes place more or less under the exact spot selected and doesn't change when the camera is moved. But it does consider an area somewhat surrounding the actual dot, presumably because the tiny area of the defined focus square is often too small to use just by itself. Maybe if I try to position the model's eyes or lips right under the dot when focusing.

The "AI SERVO" mode works, but it is so slow to react to movement that it's probably useless for shooting sports. Not that I really plan to. I believe that this was one of the "Cons" identified by dpreview.com in its recent in-depth review.

The in-between, "AI FOCUS" mode takes a long time to realize that things are moving, and then bump the camera into "AI SERVO" mode. Not that it does much good.

The relatively dim light of the strobes' model lights may not be helping, plus the camera probably doesn't have an image processor as powerful as high-end gear.

There may also be a problem with softness of the lens when shooting a full-length shot with the model's head somewhere near the edge of the image. Though with a 50mm f/1.8 Canon lens on an APC sensor at f/8 I wouldn't expect this softness to be more than negligible. I'll take some more shots with a test chart.

dnavarrojr · « **Reply #4 on:** April 13, 2010, 02:04 »

I have gotten in the habit of using AF to set the initial focus on my subject, then flipping the lens into manual focus mode to keep it there. Occasionally I'll manually adjust if necessary.

Klauts · « **Reply #5 on:** April 13, 2010, 02:17 »

Keep in mind that if you tilt the camera under a certain angle the distance you focused on first will differ from the distance your subject may now be at.
I'll use pitagora's theorem for simplicity to illustrate.

Let's say C was the distance you focused on than you tilted the camera 45 degrees. Your focus distance if locked will remain at 7.07 m but your subject is now at 5m. This is a pretty extreme example but still...

GeoPappas · « **Reply #6 on:** April 13, 2010, 06:31 »

Quote from: pet_chia on April 12, 2010, 22:06

OK, after some tabletop tests it seems that the "ONE SHOT" mode is reliable. The focus takes place more or less under the exact spot selected and doesn't change when the camera is moved. But it does consider an area somewhat surrounding the actual dot, presumably because the tiny area of the defined focus square is often too small to use just by itself. Maybe if I try to position the model's eyes or lips right under the dot when focusing.

You might want to try and switch the metering mode to spot or partial. This will reduce the amount of area in focus and therefore should help with focusing on your selection.

cathyslife · « **Reply #7 on:** April 13, 2010, 07:41 »

Quote from: dnavarrojr on April 13, 2010, 02:04

I have gotten in the habit of using AF to set the initial focus on my subject, then flipping the lens into manual focus mode to keep it there. Occasionally I'll manually adjust if necessary.

Sometimes I do this too. On tabletop shots, sometimes I just use manual focusing. I also use spot metering and use the center focus point for the most part.

WarrenPrice · « **Reply #8 on:** April 13, 2010, 11:42 »

Since my next large purchase is probably the T2i, I am more than a little interested in this problem. I have always used Nikon. Switching will be traumatic, especially if I run into such problems. Is this an isolated problem ... or is it a problem for everyone using the T2i?

I DO shoot sports and need focus tracking for oncoming, hi-speed vehicles. I guess the tracking is a second problem.

First, I need to learn about any problem with the "focus area."

PS: is the focus speed related to the lens or is Canon Focus Tracking built into the camera?

gostwyck · « **Reply #9 on:** April 13, 2010, 12:22 »

Quote from: pet_chia on April 12, 2010, 20:03

Everything about the camera works great (still photos, not trying videos yet) but one problem has been happening consistently. Shooting about 15-20 feet (5-6 meters) away from from a standing subject with a 50mm lens (around 85mm effective with APS sensor) at f/8 I find it almost impossible to get the camera to focus on the subject's face in full-length shots - especially if they are holding anything in front of them like a camera, football etc.

There are 9 autofocus points. I use the menu/buttons to switch from "camera decides which zone to autofocus" to manually select the autofocus point, picking the point nearest the subject's face. I tilt the camera slightly to place the point over the face, hold down the button halfway and it locks. Then I quickly recompose and shoot, before the subject moves. But the focus is virtually never on the face, but always somewhat forward, in the region of the object they are holding (maybe 6 inches in front).

Do you think that the camera is basically overriding my selection of the focus point and trying to compromise between the area of the image under the selected point, but still taking data from some of the other points? I can see how in amateur shooting this might help save someone's vacation shots, but when I absolutely must have the eyes and teeth "tack sharp" at 100% it's very annoying.

You should be able to see what the camera is focusing on from which red dot is blinking. Autofocus is fine for most shots but it certainly has it's limitations. I'd regard trying to focus on someone's eyes on a full-length shot from 5-6m when they are holding a football in front of them as too tricky for autofocus. Just switch to manual and the red dot should confirm when you have sharp focus where you want it. I switch to manual quite frequently even when using a 1Ds MkIII. Autofocus is there as an aid but you should always be in control of the camera.

Xalanx · « **Reply #10 on:** April 13, 2010, 14:29 »

Alright, umm... I went to read the review at dpreview.com and of course I skipped a lot of pages. Then I got to the sample shots.
Is it just me, or my 5D classic just got beaten badly at iso 3200?? see here (warning - 18 mp image).

pet_chia · « **Reply #11 on:** April 13, 2010, 15:15 »

Quote from: WarrenPrice on April 13, 2010, 11:42

Since my next large purchase is probably the T2i, I am more than a little interested in this problem. I have always used Nikon. Switching will be traumatic, especially if I run into such problems. Is this an isolated problem ... or is it a problem for everyone using the T2i?

I DO shoot sports and need focus tracking for oncoming, hi-speed vehicles. I guess the tracking is a second problem.

First, I need to learn about any problem with the "focus area."

PS: is the focus speed related to the lens or is Canon Focus Tracking built into the camera?

1) I don't think it's a major problem for studio shooting, but just a limitation that is more or less par for the course for a "prosumer" versus "pro" camera. Also my own inexperience. I would say that the autofocus is better and more reliable than my previous camera Nikon D40 which is reasonable in that the T2i is a newer model and twice as expensive.

Judging from my tabletop tests where it seemed to take a second or two to recognize "motion" (actually me waving the camera around) I concluded that AI SERVO mode iss not fast enough to handle race cars or football players, but I haven't tested this in the field.

2) Not sure if its the lens or the camera that's slow, I only have the kit zoom lens and the 50mm f/1.8 lens to compare and haven't tried any other Canon DSLRs.

dnavarrojr · « **Reply #12 on:** April 13, 2010, 18:40 »

It has a lot more to do with the lens than the camera. A professional quality lens with a faster servo for focusing is necessary for those "pro quality" action shots. The kit lens is a cheap lens (still good, don't get me wrong) made for soccer moms and dads, not professional photographers.

jeff_t2i · « **Reply #13 on:** July 18, 2010, 10:20 »

Hello, pet_chia,

Just got T2i and I found similar issue with my EF 50mm F1.4 lens: shotting an object about 3-5m away the focus spot is 5/10 cm closer/forward. I did quite some test and this issue is consistent.
Wonder if you found a reliable solution for this. I set AF to ONE-SHOT, use single centeral AF point, set metering mode to be SPOT, and also try to aiming object using the area that a little below the central AF point. I also tried other AF point. None of them really helps. The focus spot is consistently forward/closer.
When shotting things that is very close, say around 1m, the focus spot is quite accurate.

I just updated my firmware to 1.08. It is not helpful either. It is difficult to notice this issue using my kit lens (18-135mm) since the maximum aperture is much smaller.

I consider this is a serious issue hope someone could help.
Jeff

WarrenPrice · « **Reply #14 on:** July 18, 2010, 11:23 »

Have you contacted Canon? I just got mine, too. I haven't noticed the problem but am now a bit concerned???

jeff_t2i · « **Reply #15 on:** July 18, 2010, 12:58 »

I hope this is a problem only happen to a few cameras, ie it is not a design problem.
I received reply from canon but it does not help.

------------------------
Canon's reply:

Thank you for contacting Canon product support. We value you as a Canon
customer and appreciate the opportunity to assist you. I'm sorry to
hear that you are receiving images that are 3-5 cm closer/forward than
you had expected.

There is a possible remedy without sending your camera to a facility for
repair. All you need is a pencil eraser and a clean dry towel.

1. Check the camera by taking a picture without the lens attached.

2. Remove the lens from the camera and use the eraser on the metal
lens contacts at the base of the lens.

3. Wipe the area with a clean dry towel and attach the lens to the
camera.

If your camera is still having the same issue, you will need to service
your camera body and lens.

cathyslife · « **Reply #16 on:** July 18, 2010, 13:15 »

I am using a 28-135mm lens (not the soccer mom or dad lens OR kit lens) and I notice focusing problems intermittently. I actually came up with the same solution that Canon has suggested but I didn't try the eraser. I usually just take the lens back off, wipe both of the contacts with a paper towel, and reattach the lens. I don't know why, but sometimes it just doesn't seem to seat correctly. That usually solves the problem. I will try the eraser tip too.

I notice it when I switch from my 100mm, 70-300mm or back to the 28-135mm.
Canon doesn't really explain why you need to take a picture without the lens attached though. I guess that is just to check that the camera is indeed taking a picture?

PS. I use a Canon Digital Rebel and a Canon 50D. I have noticed it with the 50D. Not to say it didn't happen with the Rebel, it's just been a while since I've used that body and don't remember if the problem existed back then too or not.

jeff_t2i · « **Reply #17 on:** July 18, 2010, 14:01 »

Anyone else using T2i + 50mm f1.4 and having this focus issues?
hope this is not a design issue, ie the sensor/algorithm for focus is just weak for basic rebel models.

sharpshot · « **Reply #18 on:** July 18, 2010, 16:22 »

I use it with the 50mm 1.8 and haven't had a problem. Over on the dpreview forum, there were a few people with this focus problem and one reviewer had it. Perhaps there are a few faulty cameras? I don't think many people have the problem because there would be more complaints.

jeff_t2i · « **Reply #19 on:** July 18, 2010, 16:56 »

Thanks for the message.
I guess it is not a common problem so probably the best thing I can do is exchanging for another camera.

Microbius · « **Reply #20 on:** July 19, 2010, 03:24 »

We were getting auto focusing issues with the T2i with 18-55mm kit lens out of the box. Took it back for a replacement and so far no problems with the new body and lens.

jeff_t2i · « **Reply #21 on:** July 19, 2010, 03:36 »

Thanks for the message. that's good news.

dnavarrojr · « **Reply #22 on:** July 19, 2010, 18:54 »

I just got my $99 F1.8 a few days ago and I'm having no issue with it.

Albert Martin · « **Reply #23 on:** July 20, 2010, 02:24 »

50mm 1.8 II is much better choice regarding price and quality over 50mm 1.4.

There is no significant gain in having 1.4 over 1.8.

Try this trick:

Push ISO up... Then focus, and after that just get your ISO back to shoot properly. Or, use LiveView on Canon 550D - it works amazingly well and focus manually!

BTW, if there is no some malfunction you should get your focus exactly as seen on that 3" LCD display on your camera.

traveler1116 · « **Reply #24 on:** July 20, 2010, 06:53 »

Quote from: Microbius on July 19, 2010, 03:24

We were getting auto focusing issues with the T2i with 18-55mm kit lens out of the box. Took it back for a replacement and so far no problems with the new body and lens.

Hmm my girlfriend just bought one with the 18-135mm IS lens and the focus is way off on that, unusable. The problem is we bought the lens in the US and are now in Bulgaria which makes it nearly impossible to get the problem solved, we can't even ship it back to the US because Canon won't accept it from foreign countries and to send it to family requires getting a customs report from the airport in Sofia. Pretty ridiculous, maybe someone here knows someone at Canon and can help us out? The camera seems fine with my 50mm 1.8 and 17-40mm but unfortunately now i dont have a wide angle lens for my camera.

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Author Topic: Canon T2i/550d focusing issue (Read 49877 times)

pet_chia

madelaide

pet_chia

pet_chia

dnavarrojr

Klauts

GeoPappas

cathyslife

WarrenPrice

gostwyck

Xalanx

pet_chia

dnavarrojr

jeff_t2i

WarrenPrice

jeff_t2i

cathyslife

jeff_t2i

sharpshot

jeff_t2i

Microbius

jeff_t2i

dnavarrojr

Albert Martin

traveler1116

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