Focusing Problems

[timwaters77]

Before I begin, I would ask the moderators to allow this to stay here. I would like both Canon users and Nikon users to chime in and afraid I won't hear from the Nikon users if I post in the Canon thread.

I have been having some focusing problems with my Canon 50d and lenses (70-20 f2.8, 28mm f1.8, 50mm 1.4). It particularly happens in low lighting situations, but not exclusively. It will often focus the background, leaving the foreground blurring, or it will just not focus where I want it. And so so slow focusing in low light situations.

In March, I am going to be dropping some cash to upgrade my body and get a couple more lenses. The plan was for the Canon 5D Mark II and a couple really good zooms.

But I am hearing that this focusing problem is something common to Canon non 1 cameras, even the 5D Mark II. I have read this online and and from fellow Canon using photographers.

So I guess my reason for posting is wondering if someone can talk me out of selling the equipment I have and switching to Nikon.

I have done really well with my Canon....but have also missed my fair of shots because of the focusing problems.

Thoughts? Experiences?

[Greg McCary]

Well I shot Olympus and not sure about Canon but with my camera I can control which focusing points are on or off. From time to time I can knock something out of whack and some of the focusing points gets turned off. Is it back focusing even if the proper focusing point is indicating correct focus?

[Franglais]

Nikon shooter, Canon observer..

The best bet right now for you is the Canon 7D. Canon followed the Nikon D300 and made a reporter-sports model (like the 1D series) with excellent autofocus. The 5DMk2 is intended more for the wedding photographer market and it has an autofocus system with less performance.

I say "right now" because there should be a number of new products announced before the summer, including a 5DMk2 replacement. Canon may improve the autofocus unit. They probably won't use the 61-point unit from 1Dx but they might slip the 7D unit in.

Nikon are also likely to change many models. Nikon will probably release a new autofocussing unit but the current 51 point unit is excellent (it focusses in conditions too dark for me to see). It's used in all the current Nikon range from D300S upwards.

[freygr]

Low light and open apertures, it sounds like DOF problems. It does not mater slow focusing happens in all cameras in low light. In low light and taking mirco photographs use of MANUAL focusing in alomst always required.

[timwaters77]

thanks all.

I am a wedding and portrait photographer so have been looking at getting the Mark II.... just wish Canon would announce whether or not they are releasing its replacement sometime soon.

[Anbesol]

So I guess my reason for posting is wondering if someone can talk me out of selling the equipment I have and switching to Nikon.

That would be counter-productive. The technologies between *every* company are very competitive, such that if you are having problems with one - you are going to have the same problem on others (especially of equally priced caliber).

Are you setting the focus to spot focus, or are you letting the camera decide where to put it. Conventional technique for focus control is to use spot focus and set your focus point before you frame the shot.

[Franglais]

...
I am a wedding and portrait photographer so have been looking at getting the Mark II.... just wish Canon would announce whether or not they are releasing its replacement sometime soon.

Some dates:

August 2005 Canon 5D (12 Mpix) announcement
August 2007 Canon 1DsMk3 (21Mpix) announcement
July 2008 Nikon D700 (12Mpix) announcement
October 2008 Canon 5DMk2 (21Mpix) announcement
November 2011 Canon 1Dx (18Mpix) announcement - no replacement for the 1Ds
Summer 2012 Olympic Games

I think that it's unlikely that Canon will release the 5DMk3 in the next couple of months:

- Canon don't need to. Nikon have not yet announced anything that directly competes with it (the D700 is a reportage type camera not specifically pointed at weddings or fashion). If (as expected) Nikon announces a camera closer to the 5DMk2 then Canon might announce the 5DMk3 some time after
- Canon have only just announced that the 18Mpix 1Dx has enough Mpix to satisfy most users and they won't be delivering till March. It is unlikely that they announce a 5DMk3 with more MPix than the 1Dx immediately. If it has the same sensor then it will steal sales from the 1Dx.
- Canon and Nikon are probably concentrated on their top pro models for the Olympic Games. The second-line pro models might wait a bit longer

[Anbesol]

Is this backfocus issue, user error, or camera error? I think we need to find out which one it is before advising. The 60D is no slouch with AF, the 7D is better but we can't know for sure that the problem hes having will be fixed just by a better camera.

[gryphonslair99]

Let's talk focusing technique. You don't say what techniques you are using. Single focus point, multiple focus points, focus and recompose? It matters.

Low light, use a single focus point on the exact part of the subject you want in focus. You also need to have a working understanding of DOF while you do this to get the subject into focus. Also pay close attention to your focus point and keep it dead on the subject. This may mean altering the focus point from the center point. If that focus point shifts slightly off subject your focus will change.

As for slow focusing. The camera needs contrast to focus. While the human eye can adjust for low contrast, a camera cannot make the same kind of adjustment. The focus will naturally be slower in low light as it hunts for that contrast that it can focus on. A white shirt in a dark room is easier to focus on than a black shirt in a dark room.

[monkey44]

Been having this problem too - Canon 30D - for awhile, sometimes great shot, sometimes it seems back-focus on the outlying areas. Sometimes it happened so often under certain conditions in the field, I thought I had a bad lens.

Have played around with it and decided it's a focus-point issue ... the camera will sometimes focus on points it 'finds are best overall' in the scene, and not always what the shooter thinks or wants.

Visualize a bird or a fox moving about in heavy brush, for example - auto-focus will want to hit the branches around the animal. So, if you're in multi-focus points, you get the bird as only ONE point. A camera is technology and only as good as its operator. So, when you auto-focus with multi-points, make sure you recognize which points the camera has determined are priority for its settings.

There's probably more to it than that one thing - but all of us know, a combination of factors creates that one excellent image we all look for every outing. But this auto-focus w/multi-points really affects the DoF more than and other factor except maybe TV, and it seems this OP is stating a situation where DoF is important as it relates to the primary subject. When the DoF allows some bacjground spot other than the actual subject to influence the primary focus points, the subject will often appear soft.

Suggestion to OP and anyone else when happens: Look it the photo in various stages of Zoom in the photo program and see if you can find one or more points that are in focus, but not the subject. If you find that/those, then the auto-focus probably hit those instead of or in addition to the subject and then leaves the subject soft and those background focus points sharp.

[SmartWombat]

First of all take control of the focus points, don't let the camera choose!
I commonly use the centre AF point only because it is the most sensitive.
And custom program the * button for focus so I can separate focussing from compsition and exposure.

Secondly, the Canon flash will emit a structured red light pattern in low light to aid the AF.
I know it's expensive to buy a flashgun just for the AF assist, but it worked for me in party shots

If you don't want to use AF, then change the focus screen to one more suitable.
Type EF-D precision with grid or EF-S precision without the grid.

Video showing screen changing in a 4D (similar to your 50D)
Canon Professional Network - EOS 40D Focus screen

[Photo-John]

This definitely sounds like a technique problem and not a camera problem. However, to be sure, I'd need to know more about the camera setup. What focus mode, what focus points and what kind of subjects. I'd like to see some sample photos, too. That said, I owned the EOS 50D, I had a 5D Mk II for review for a couple of months and I own a 7D now and this doesn't sound like a problem I've ever had. Like SmartWombat said, the first thing is to take control of the focus points. I never let the camera choose the focus point. That guarantees that at least some percentage of your photos the camera will choose something that you wouldn't. I prefer to make my own mistakes

[Greg McCary]

When Olympus first went from three focus points to eleven I read about many photographers complaining with back focus. They just were not paying attention well to what focus point the camera chose. Their E3s were fine. Some even sent them back to
Olympus. Does the Canon not have LEDs in the finder that indicates your focus point?

[onesickpuppy]

If I was the original poster....I would do the following

Since you are using a Canon....load the Canon software that came with the camera...DDP

It has an option to show where the focus point is....so load the image, and select that option

From there you will be able to tell what happened.

Normally I always use center point focus....but every once in a while (as mentioned above)
I some how hit the button that allows to chose the focal point and I move it...or I had moved it on a shot before...and forgot to set it back to center.

Then if your focal point is centered..then you have to look at if even centered, if it found something in the background to focus on...and then DOF took over.

[Photo-John]

Does the Canon not have LEDs in the finder that indicates your focus point?

The Canon DSLRs all have focus point indicators in the viewfinders. That's why this sounds more like a technique issue to me than a camera problem. If you select the focus point yourself there should be no problem. If the problem appears random and unpredictable, then I'm almost positive that the poster is allowing the camera to choose the subject - never a good strategy as it will let you down way too often.

[Photo-John]

If I was the original poster....I would do the following

Since you are using a Canon....load the Canon software that came with the camera...DDP

It has an option to show where the focus point is....so load the image, and select that option

From there you will be able to tell what happened.

Great advice!

By the way, I used to only use the center point, too. But over the past three or four generations, I've found Canon's DSLR auto focus has improved enough that I feel comfortable using off-center focus points - even with continuous auto focus for sports

[armando_m]

... custom program the * button for focus so I can separate focussing from compsition and exposure....

Is this usable with moving targets ?

I know I can do it with my nikon, but never done it, I just focus and recompose without letting go of the half shutter

[SmartWombat]

Is this usable with moving targets ?
I know I can do it with my nikon, but never done it, I just focus and recompose without letting go of the half shutter

Yes, either I get full AI servo tracking AF for moving targets, or I use it to focus on a spot of tarmac and then shoot prefocussed without pressing the button.
Best of both worlds for me, AF when I want it and separate from shutter release and AE.