How to get better focusing?

[zobx]

As in many cases, for a long time I was just shooting landscapes, occasionally some street stuff and standard portraits. For that purpose I was quite happy with my 30D (besides it's tendency to underexpose). However, recently there is a more challenge for me and the camera - meanwhile I'm a father of 17 month old girl and I really enjoy making photos of her while playing or simply running around the apartment. Of course, she is getting faster and more unpredictable in her movements and I've noticed that number of keepers is rapidly decreasing due to many out of focus shots.
Currently I'm using following lenses with my 30D:

• 17-85mm f/4-5.6 IS
• 85mm f/1.8
• 70-200mm f/4 L

Shooting indoors in low light conditions was a good reason to add also an 430EX in order to provide some more light. But that didn't fix the problem - still many out-of-focus pics. Of course, both 85mm and 70-200mm are often too long for indoor so most of my shots are done with 17-85mm. But basically, I didn't notice some major difference in focusing between these 3 lenses on my camera in such conditions. AI servo and experimenting with focusing points also didn't bring some considerable improvement.

Now, what might be the best solution for this problem:
a) Learn how to better utilize the existing equipment?
b) Get a better camera?
c) Get a better (more suitable) lens?

On a) I've got an impression I've already tried a lot and I can't imagine something else that would introduce some significant improvement. But maybe I'm still missing something??

Speaking about b) yes, I know there are cameras like 7D with better focusing (and ISO performance) which could certainly make it easier in low light. I'm just not sure how noticeable would be the difference actually (and is it worth the money)? Of course, there are actually many other nice things on 7D I would like to have. And one I wouldn't - it is even heavier than my 30D. :-(

And on c), well, even apart from this focusing issue I was already considering replacing the 17-85 with something faster, most likely with 17-55 f/2.8. I was also looking at some wider primes like 28mm f/1.8 but wasn't convinced about picture quality compared to 17-55 (and some L like 35mm f/1.4 is a bit above what I'd like to invest in a single lens). However, at the end of the day I'm again not sure if a better lens is really going to solve my problem with focusing in low light?

So, any tips or sharing similar experiences would be highly appreciated.

BR

P.S. In the example below she was calm enough to allow me this relatively good focused photo.

 

[mSum]

I have a 3 year old and it get's even harder. I mostly use a cheapo Canon 50mm 1.8 in the house and I use AI Servo. I'd think the 85mm is a bit long for shooting in the house. I'm also considering a 35mm f2.

Don't ignore the 60D, it's roughly the same size as your 30D but has the same ISO performance as the 7D. It has less AF points but its AI Servo tracking system works great.

--
http://www.flickr.com/photos/m_summers/

 

[loafer]

here are my tips

1. use the back - button focus technique. On the 30d assign AF to the * and AE to the shutter button.

2. learn to use all the af points. The limitations of focus - recompose are "exposed" with these digitial cameras where micro-image analysis is much easier.

3. keep the shutter speed high. Any hand held (non-IS) shot where shutter speed is greater than 1/(2x focal length) is suspect for camera movement. Most of the time 1/(focal length) is ok - but not ALL the time. Conversely - do not fear high ISO - 30D is fine at ISO 1600

4. It could be the hardware. Cameras and lenses may not match each other or they could be out of adjustment. Live view focus eliminates this issue and the micro-adjustments on some models are helpful. It is not that expensive to send the hardware to Canon for adjustment.

 

[zobx]

I have a 3 year old and it get's even harder. I mostly use a cheapo Canon 50mm 1.8 in the house and I use AI Servo. I'd think the 85mm is a bit long for shooting in the house. I'm also considering a 35mm f2.

Don't ignore the 60D, it's roughly the same size as your 30D but has the same ISO performance as the 7D. It has less AF points but its AI Servo tracking system works great.

Frankly, I never considered 60D as a much of an upgrade to 30D. You are of course right about ISO performance, however so far I didn't find any clear hint that 60D has significantly better AF than 30D. Actually I didn't find any in-depth information on the web about AF on 60D. Otherwise, I don't really care about more megapixel or swivel screen. On the other hand, 100% viewfinder, AF fine tune and 19 cross-type AF points on 7D sounds much more useful to me. Of course, all that has also it's price, I'm fully aware of that.

But anyway, if there are some clear indications that 60D provides a significantly better AF performance compared to 30D I would probably take a closer look on that camera.

BR

 

[akin_t]

I had the same problem. I'm betting several people do too without realizing it.

Usually our focus technique goes something like this.

1) Lift viewfinder to face
2) Select focus point
3) Press AF-ON (or half shutter)
4) Wait for focus confirmation light
5) Click the shutter

In between steps 4 and 5 some of us move our cameras ever so slightly; as a result, the previously acquired focal distance is no longer resting on the subject you acquired focus for.

If you shoot at large apertures, you will notice this as the DoF is much shallower there. I don't have any advice for avoiding this other than to trip the shutter as quickly as possible.

I believe this is the major cause for most focus errors, there's just no way people can tell me they do not move in between focus confirmation and clicking the shutter. Heck even a slight tap of the shutter button moves the camera (albeit very slightly) ... What I do is leave my finger half pressed on the shutter (it only meters, doesn't focus) and acquire focus with AF-ON ... The second I hear that beep I depress the shutter fully.

This helps because your finger has to travel less distance to trip the shutter, and thus the kinetic energy your finger is inducing on the camera body is much less.

I know it sounds very nerdy and very far-fetched, but its the damn truth. It has certainly worked for me.

 

[Y Hafting]

To achieve good focus indoors (low light) without using disturbing flash to help, you basicly need to use a fast lens (f2.8 or wider) together with center point focus. You should also definitely have USM.

You already have the 85 1.8 which is good, but it will probably be way too narrow in many situations.

I cant tell how much a newer camera will help, having a 30D myself, but im fairly sure that a 2.8 or wider lens does more than having a new camera and being limited to f4.

I'd give my vote for the 28mm 1.8, it is a very good focal length on a crop camera for indoor shooting. At the moment it is my most used lens.

F2.5 1/13s ISO3200 (+1EV in most areas) vignette added later









It works well outdoors too:





Getting good focus when movement is involved is always difficult, but practice does help a bit. In low light the camera will never respond as quickly as in good light. When using the non-center focal points you have to be very careful to have a relatively bright and contrasty area for the focal point in use.

Best of luck!
-Yngve

 

[zobx]

Thank you very much for the tips. See my comments below.

here are my tips

1. use the back - button focus technique. On the 30d assign AF to the * and AE to the shutter button.

I was considering that. But isn't this going to introduce an additional "lag" between focusing and shooting (because I need to coordinate and work with two buttons) and consequently reduce chances to catch the "best" moment? Somehow I don't have a good feeling about that. But maybe I should try it..

2. learn to use all the af points. The limitations of focus - recompose are "exposed" with these digitial cameras where micro-image analysis is much easier.

You mean turn all AF points on and let camera select the focus point automatically, or to select the AF point manually as needed? I was already experimenting with both these options: in first one the camera selects too often a "wrong" (suboptimal) AF point and in second I was almost always simply too slow. This is definitely something I could practice more.

3. keep the shutter speed high. Any hand held (non-IS) shot where shutter speed is greater than 1/(2x focal length) is suspect for camera movement. Most of the time 1/(focal length) is ok - but not ALL the time. Conversely - do not fear high ISO - 30D is fine at ISO 1600

You are right about that. In many I'm leaving shutter speed too close to the lower limit and I'm a bit too conservative with ISO.

4. It could be the hardware. Cameras and lenses may not match each other or they could be out of adjustment. Live view focus eliminates this issue and the micro-adjustments on some models are helpful. It is not that expensive to send the hardware to Canon for adjustment.

I was thinking about that too. However, I haven't noticed similar issues with focusing on good lighting (outdoors).

BR

 

[Sailor Blue]

I suspect your primary problem is that your wide angle zoom simply doesn't have a large enough aperture to allow your camera to focus quickly and accurately so you wind up taking the picture before the correct focus is achieved.

With a fast moving subject (and all children of that age who are awake fit into that category) focus can also be quickly lost because there just isn't enough light getting through that lens to allow the AF system to work properly. Changing to a higher ISO won't help with AF since AF and image acquisition are two separate systems.

With the 430EX you should be able to shoot direct flash at distances of 4-10 feet at an ISO of 100, a shutter speed of 1/250 sec., and in the f/4-f/8 range without any problems.

I think the answer to your question is that you need a faster lens. Don't forget that the 30D is a crop sensor camera so there is a multiplication factor that you have to apply to get the apparent focal length of any lens. For indoors you want something in the equivalent of 35mm to 50mm-75mm. Any longer and you will have a lot of trouble using it indoors.

 

[mhz888]

As I look at the shot, it looks to me like you might be letting the camera choose the focal point to use (by having all points selected)? I don't know the 30D at all, I've a 20D and a 7D, but in the shot you posted, it looks like her near sleeve is focussed well, and her face maybe slightly less so? On my 7D, with AI servo focus selected, and all focus points selected (I NEVER USE THIS MODE ), I believe it will shift to the closest thing it can lock focus on. That may or may not be what you want it to do. Of course, this may not be what the 30D does, but based on what I see in your "focused" shot it seems like a possibility I didn't see mentioned. One other thing that could be happening, that I as a dad of three know very well too - for lack of a better term, I will call "excited jerk." Now, we barely know each other, so no, I wasn't calling you an excited jerk. What I am referring to is that eagerness to capture the moment, that you forget your technique with the shutter button. You jerk/stab at the shutter button instead of squeezing it gently. With the slightly longer shutter speeds, I think this can cause noticeable shake and contribute a lot to the softness and out of focus issues. Coupled with many of the other suggestions here, I think that could be part of the problem. I'll also go against the grain here and suggest that buying a faster lens might not make things better and might make them worse, as the narrower DOF you'll get when it's wide open is both a blessing and a curse. Just don't let your wife see my post and make sure she reads the posts about faster glass, twice! When it doesn't fix the issue, you'll have gotten good glass and have her poised to buy a better body too!

--
-Kevin

 

[zobx]

As I look at the shot, it looks to me like you might be letting the camera choose the focal point to use (by having all points selected)? I don't know the 30D at all, I've a 20D and a 7D, but in the shot you posted, it looks like her near sleeve is focussed well, and her face maybe slightly less so? On my 7D, with AI servo focus selected, and all focus points selected (I NEVER USE THIS MODE ), I believe it will shift to the closest thing it can lock focus on. That may or may not be what you want it to do. Of course, this may not be what the 30D does, but based on what I see in your "focused" shot it seems like a possibility I didn't see mentioned. One other thing that could be happening, that I as a dad of three know very well too - for lack of a better term, I will call "excited jerk." Now, we barely know each other, so no, I wasn't calling you an excited jerk. What I am referring to is that eagerness to capture the moment, that you forget your technique with the shutter button. You jerk/stab at the shutter button instead of squeezing it gently. With the slightly longer shutter speeds, I think this can cause noticeable shake and contribute a lot to the softness and out of focus issues. Coupled with many of the other suggestions here, I think that could be part of the problem. I'll also go against the grain here and suggest that buying a faster lens might not make things better and might make them worse, as the narrower DOF you'll get when it's wide open is both a blessing and a curse. Just don't let your wife see my post and make sure she reads the posts about faster glass, twice! When it doesn't fix the issue, you'll have gotten good glass and have her poised to buy a better body too!

I would like to separate two cases:

• Shots that are not perfectly in focus due to wrongly selected AF point, slight movements of camera (yeah, "excited jerk" ) or object between focusing and shooting, etc. I'm aware of that and I know there is still a room for improving my technique, but was not my primary concern.
• Shots that are totaly out of focus, with objects blured to unrecognizability, or situations where camera even didn't make any shot because it was unable to lock the focus (it happens sometimes as well!). Such cases are what makes me a bit frustrated and a reason for this posting.

Speaking about faster lens, you are right, wide open lens will often produce soft shots due to thin DOF especially with fast moving target, I had that many times with my 85 f/1.8. But I thought something between 2.8 and 4.0 could still help camera to focus faster (is it a general rule?) and on the other hand camera should provide higher ISO in order to ensure enough shutter speed. That might be a working combo, however it is suggesting buying both new body and another lens. Exactly my wife's favourite combination. ;-)

 

[zobx]

To achieve good focus indoors (low light) without using disturbing flash to help, you basicly need to use a fast lens (f2.8 or wider) together with center point focus. You should also definitely have USM.

You already have the 85 1.8 which is good, but it will probably be way too narrow in many situations.

I cant tell how much a newer camera will help, having a 30D myself, but im fairly sure that a 2.8 or wider lens does more than having a new camera and being limited to f4.

I'd give my vote for the 28mm 1.8, it is a very good focal length on a crop camera for indoor shooting. At the moment it is my most used lens.

F2.5 1/13s ISO3200 (+1EV in most areas) vignette added later

Thanks for suggestion and examples. The first one looks really good for ISO3200. Did you make any noise reduction in PP?

BR

 

[GoldenSpark]

Have you done a focus test with your 30D? With my faster lenses my 30D was sufficiently out to be a problem.
I now have a 50D so MFA has eliminated that problem.

Also, don't expect great focus accuracy on a lens with wide open aperture smaller than f/2.8 - it's only lenses that are f/2.8 or faster that allow the body to give focus accuracy of + - 1/3 of the Depth of Focus. Slower lenses are only quoted as + - 1 DOF.

What that means is the target object focus feature (e.g. the eyes etc.) may be at the extreme end of the focus depth.

look here and dial in a few examples to show you what I mean;
http://www.dofmaster.com/dofjs.html

Example;

85mm focal length on your 17-85, @ f/5.6, 200cm (2m) distance to subject, DOF is 11.4cm. BUT all that focus depth could be in front or behind the point you want to be in focus.

Try taking a shot with these conditions and look at how sharp it is at the extreme ends of the depth of focus. You can do this by taking a shot of a ruler at a shallow angle. Canon use "acceptably sharp" to describe what their focus accuracy means. This may not be acceptable to you.

Using a f/2.8 or faster lens at least gives you better accuracy. The focus point will at least be in the middle third of the full depth of acceptably sharp DOF, but remember then your DOF is shallower if you don't stop the lens down. If your 30D, or the lens connected, is out, it may mean your shots are always slightly front or back focussed, cancelling out the advantage of the increased focus accuracy. You can cure this by stopping down, but at the expense of shutter speed or ISO.

I had this on a 70-200 f/4 L lens. You can tweak the 30D by moving the mirror stop, and I did this with mine. It transformed the 70-200, but then some other lenses were out the other way!

I would recommend the 50D route, cheaper than the 7D, if only for the MFA.

 

[jsanch08]

You face several hidden challenges with photographing children.

1. Often, if you focus on a face, the detail in the face is below the resolution of the AF sensor itself, and, focus fails, although, on Canon, the green focus confirmation light will light up and enable you to make a picture. This happens to me with my 50D all the time, so, don't think upgrading will help you a great deal.

2. AF module focus is based on AF module contrast differences (not based on the actual imaging sensor peak contrast). These AF module differences, based on my own experimentation, and the experimentation of others in the Nikon and Pentax forums, indicates that the AF module max contrast is dependent on lighting type. Canon actually formally acknowledged that in their white paper on the 50D where they changed the AF to sense two wavelenghts of light rather than one (their words). Bottom line: when you are under tungsten, your AF module, for the same lens and camera, will have a different focus point than daylight and a different focus point than flourescent light.

I have experimented with the different light sources in my own environment and have set MFA in my 50D based on the repeatable differences the AF module presents depending on light source. This single issue probably explains more "my camera is out of focus" posts than anything else out there.

3. Amplitude of the light source. Indoors, in low light, the AF module, even on 50D, has trouble with contrast differences between yellow and green, or red and yellow for example. So, you might focus on a very visible red/yellow strip on your daughters dress, and, get a failure.

WHEN IN DOUBT, I now use my 50D live view mode, at 100% view, with an aperature no less than 4.0, to manually focus, then, take the picture. This is the only way I know to absolutely nail focus in critical situations.

 

[guy schlacter]

2. AF module focus is based on AF module contrast differences (not based on the actual imaging sensor peak contrast). These AF module differences, based on my own experimentation, and the experimentation of others in the Nikon and Pentax forums, indicates that the AF module max contrast is dependent on lighting type. Canon actually formally acknowledged that in their white paper on the 50D where they changed the AF to sense two wavelenghts of light rather than one (their words). Bottom line: when you are under tungsten, your AF module, for the same lens and camera, will have a different focus point than daylight and a different focus point than flourescent light.

I have experimented with the different light sources in my own environment and have set MFA in my 50D based on the repeatable differences the AF module presents depending on light source. This single issue probably explains more "my camera is out of focus" posts than anything else out there.

it's funny but impotent that you raise this issue if coherent light sources for AF. My equipment (7d and 24-70 f2.8) went back and forth to Canon, with multiple technical phone calls with their upper tier support, and almost thirty hours total including experimenting and analyzing. THE biggest frustration was the maintaining that there should be a single MFA value capable of handling incandescent And fluorescent lighting at f2.8 and 70mm 6-10 f eet away which I proved un true multiple times to Canon. They never recanted, but eventually started to only say that the pair was in spec and the tightest calibrated they have seen. They could have saved me huge amout of time had they not clung to the notion of a single mfa for these two vastly different AF conditions caused by the two different light ing situations. My mfa varies by about 9, with the fluorescent being the lower.

-Guy

WHEN IN DOUBT, I now use my 50D live view mode, at 100% view, with an aperature no less than 4.0, to manually focus, then, take the picture. This is the only way I know to absolutely nail focus in critical situations.

 

[Y Hafting]

Thanks for suggestion and examples. The first one looks really good for ISO3200. Did you make any noise reduction in PP?

BR

Actually i have pondered a bit on why it was even possible myself, but the lighting here is a bit strange. In normal mode it doesnt look good at all (bad colours and contrast). Hence in contrast to most portraits i used DPP's linear option on this one. I haven't found anything that easily will match that setting in any other process, but i guess you can achieve the same with curves only in LR or PS (with much trouble i assume, i have never been able to do so myself..) However the picture is also a combination of several such "exposures" blended together such that different areas come out as they should.

To achieve proper brightness all over the place, i combined 3 or 4 different exposures from DPP, blending them together in PS using a mask. (i think it was something like +1.3EV, +.67EV, +0 and possibly -0.67 ). The face area does look best at approximately +1 EV. The shirt and the white background is way too bright at that exposure, and the crown was better at +.17 or so.

For noise reduction, i used only DPP with 8 Luminance setting, and 10 on the Chromatic noise. Sharpening is at 5 which i use as default- it is a bit hard i think, but less also makes the picture look worse i think. I know other sharpening methods (like high-pass filtering) will give slightly better results when viewing on screen, but they are also very time consuming..

I believe there are two reasons why parts of this picture actually looks acceptable even at "ISO 6400" with the 30D (and a color temperature of only 2500K).

1: is that the place in focus (his face) is most strongly lit by green, which means that there actually is more light registered by the sensor than in a usual image of 2500K. Normally at that colour temperature, the luminance of the green channel (representing 50% of the sensor area) is less than half of that from the red channel (and the blue channel could be even half or less than the green one). Here both green and red are quite strong, thus the noise doesn't appear to be as strong as one would normally see in a face. Perhaps the RAW data in the green channel (for the face) does match that of an image normally being taken at ISO 800 or so at that color temperature- hence it looks much better than expected.

2: if i use a normal mode on the raw file, it looks quite over-exposed. Best setting would be with an increased contrast around -1.67EV (indication that approximately ISO 1000 would be a more normal setting)- however that setting doesn't match the combination of linear exposed variants. Using linear mode makes the grainy parts less prominent, however it also ensures that one uses only a small amount of the headroom of the raw data. By leaving the darker places very dark in comparison to the lighter places, the noise doesn't show as much.

In other words, you could say that the image was being "shot to the right" which in general is the best way to avoid noise. Some parts were clearly blown (the white shirt), so i over did it a bit; but the shirt isn't as important as the face, so i'm happy with it. More luminance in the green channel than what is normal at the same color temperature doesn't hurt either...



-Yngve

 

[Y Hafting]

Using a f/2.8 or faster lens at least gives you better accuracy. The focus point will at least be in the middle third of the full depth of acceptably sharp DOF, but remember then your DOF is shallower if you don't stop the lens down. If your 30D, or the lens connected, is out, it may mean your shots are always slightly front or back focussed, cancelling out the advantage of the increased focus accuracy. You can cure this by stopping down, but at the expense of shutter speed or ISO.

Increasing the focus accuracy is often the difference between obtaining focus or not when i take pictures in low light with my 30D.

This means only using the center focal point and a prime. The picture its self may be taken using f3.5 or higher, since the aperture only need to be wide open while obtaining focus.

-Yngve

 

[Vigy]

Last week I photographed friend's grandchild she is 1 year old and very fast. Took the pics with two lenses 50/1.8m1 and 24-105L. All the pics where taken in high speed and in rounds of 3 to 4 pics around. most of the 50/1.8 pics came out ok. only 2/3 of the 24-105 pics came ok. used high iso and for the 24-105 used 1600 iso. High speed pictures will provid with more keepers. I am not a pro but I just love photography. Thats why I don't shoot with my camera...
--
Be Happy Vigy
"Without Light There Would Be No Photography".
Some pics: eos40d + ef50 f/1.8-m1 in my galleris here and more...

 

[mhz888]

Someone beat me to the reply, but having a faster lens will inprove the focussing, down to 2.8, which I believe is the limit of the focus sensor (at least on my 7D). I believe only certain sensors use 2.8, and the rest use higher aperatures, at least that's what I recall reading in the manual. Other cameras might behave differently, and unfortunately, my faimiliarity with the 30D is nil. Thanks for separating out the scenarios. I know why for the first set, but the second set sounds like either low contrast or low light or something. I've had such experiences, even with but they aren't normal, and usually happen when there's more of situation #1 happening.

Sorry I can't help more, good luck with the negotiations with the wife!

--
-Kevin