Nailing focus... *focus test 11/9*

[mchhp]

Help.

A little background: I have always loved photography. loved taking photos ever since my first film rebel G. I have grown a lot but feel like I am at a stand still. I can't seem to consistently nail focus, maybe not even ever really. I currently have a canon 50d with a 50mm f1.4 and a tamron 24-75 f2.8.

I have read the books, read the forums, etc. I just can't seem to take the next step in my skill. I have no idea what to do.

So, how did you learn to nail focus?

I do feel like i have some camera shake. I have tried staying away from wide open, i have tried keeping the ss above 1/125, even faster for my kids, lol. But, even with that advice (given by other photography boards/friends who are photographers), I still can't seem to improve any. It's very frustrating.

My most consistent subjects are my kids, which I know are harder to get but its what I have to work with. I know I am probably my worst critic. I get compliments on my photos all the time, but all I can see is the major imperfections, mainly focus.

 

[GrillMouster]

Practice with still subjects and post some examples.

 

[mchhp]

I will most absolutely get some test shots of some still objects as soon as I can.

But, for now, I do have a pic I took this past weekend of my son. He was sitting on a large rock, so he wasn't moving too much. this is sooc:

iso 500
f 3.2
ss 1/640

and here is one of my daughter:
iso 500
f 2.8
ss 1/500

these were both taken with my tamron lens

 

[Sam241]

Those photos are really small and I don't see anything wrong with them (But they are small so it's hard to tell).

Most of the time with a 50mm lens I would say that it's not a focus issue it's a depth of field issue, but without seeing an example (large scale) of a photo you feel is out of focus it's hard to say anything really.

 

[ukcatfan]

They are small on here, but I do not see what you mean. The focus seems fine. Are you by any chance not wanting the background blurred? If so, then the wide apertures are causing that. Try going for f/10-12 or so. That will give a larger depth of field (DOF). When you use more wide open apertures then you get a smaller DOF. The DOF of the 50mm at f/1.4 is really small, depending on the distance to the subject.

 

[Gianna'sPapa]

I don't see a lot wrong with the images you posted. I do have a couple of questions. Are you using autofocus or manual, AF single or continuous? Is this focus issue on all your lenses or a specific lens. Have you tried a tripod with remote on a stationary subject to remove any doubt your issue is camera shake?

 

[mchhp]

try this size out.

I use autofocus, single shot, and i choose the focus point. I understand the concept of the blurry background, and i do want that, but their eyes seem sooo soft with a close in crop.

 

[mchhp]

here is a close up crop of his face:

i also wanted to add, I seriously appreciate all the ideas, comments, critiques and help. seriously.

 

[Frantasmic]

I think the shot of your son is really good.

Your daughter's picture, the focus seems to be on the fence, just to the right of her head (that seems to be the sharpest part of the shot to me).

I would ask why you are at iso 500 with a fairly well lit day, even with an overcast day? I would think 200-300 would work with your camera.

Finally, I think Tamron, Tokina, and even Sigma make some fine lenses, but they aren't ALL fine lenses. It seems each of them have a really good lens in their lineup and others are fair. My Sigma I have (24-70 I think) is just not a clear lens as say my Canon 85mm f1.8 (which is a great lens I think).

 

[zackiedawg]

You mentioned you are picking the focus point - definitely one focus point will be more accurate than leaving it in wide focus and letting the camera choose. A few things that might be causing minor issues:

1. Are you using the spot focus center point? Usually entry level cameras have a cross point sensor at least in the center, which is more sensitive and better to use for critical autofocus. Use a single point sensor and sometimes it can be off.

2. Are you firing the shutter quickly after achieving focus? And moreover, are you half-pressing to confirm focus first, then firing? Usually the best method is to half-press to achieve focus confirmation, then fire the shutter very quickly after - the more you delay, the more you can sway ever so slightly fore or aft, or the subject can move slightly, which can throw the focus off a touch.

3. Have you tested the lens you are using for front or backfocus issues? Importantly, you may want to test it at the apertures you most often use for portrait shots - try something like the 'battery' test - start with a wide-open aperture for the narrowest DOF, and shoot a lineup of AA batteries standing on end from a 45 degree angle. Have the camera on a tripod or steady on a table or wall so it can't move. Focus on the center battery, then see if the image looks accurate. If the focus is more on the 2nd battery foreward or back, then you may have a focus accuracy issue with the camera or that lens.

4. If all else fails, you could try manual focusing, or if your camera provides it, a direct or manual focus override, whereby you autofocus, then turn the focus ring to 'fine tune' the focus. Also, if your camera has live view with autofocus capability, you might try that - live view with a Canon is going to be slow, with a big delay for the shutter, but if your kids sit still for you for a few seconds to get the shot, it might still work OK - this can be a good test because the live view system may be using a different focus method - contrast-detection rather than phase-detection...see if again your PD focus system might be off a bit.

5. You may consider renting or borrowing a stabilized lens to test - just to eliminate that as a possibility. I don't know what shutter speeds you used in the above shots, but if they were under 1/250, and you had any vibration or unsteadiness, it could be just enough to affect the focus sharpness. However, in at least the daughter shot above, the focus seems to be very sharp but just in the wrong spot...so this is a less likely issue.

 

[photo_chick]

I used to have a Rebel G also. When I went digital with a Rebel XT it felt like I was learning to shoot all over again. I had so many out of focus shots. It took me a few months to really learn the AF system and I also discovered that I got away with a lot of sloppy focus with 35mm film. Digital won't let you slide on that at all. I did have a little bit of a learning curve with my 50D as well, so don't stress. This happens to a lot of people.

If you're using single point AF and choosing the point I can think of a of few things that could be going on.

You could be shifting slightly after you focus or taking too long after you focus before you take the picture and the subject is moving. Either way your plane of focus isn't where you need it at that point.

You could be inadvertently re-focusing after you focus (I did this a few times when I first got the 50D). back button focus helps if you have this problem just remember to disable the AF trigger on the shutter button. (look under custom functions in your manual)

Your diopter could be out of whack. Even with AF if you look through that viewfinder and think something is in focus, then you'll take the picture, right? You see the rectangle confirm and think it's all good, but that sucker will lie to you sometimes so watch out. Trust your eyes first. If the diopter is wonky then you'll think it's in focus when it's not. So check it, it's easy. Just take of the lens and point to a white wall or sheet of paper. Adjust until the etchings on the focusing screen are at their sharpest. my husband used to take lots of slightly out of focus shots with my camera because I have the diopter adjusted so I don't have to wear my glasses. Now he just doesn't use my camera. LOL

It could be something wonky with the camera. To me this is the least likely cause, but it does happen. To rule it out perform a focus test. If you do it accurately it should give you a pretty good indication if it's you or the equipment.

Edited to add.. I think zackiedawg posted while I was typing because we said some of the same things.

 

[cpbjgc]

In looking at the images, the focus problem seems to be more of an issue of shallow depth of field. In the photo of your son, his nose and his hair seem to be in focus while is eyes are a bit soft. In the shot of your daughter, as Frantasmic mentioned, the fence and part of her leg is sharp.

I was wondering - do you lock focus and recompose, or just use different focus points? If you are recomposing, that can cause these issues where you have a shallow DOF as is can shift the sharp area from the original focus point. If you are instead using other focal points and not recomposing, the points could be missing focus. I have a 50D as well and stick to the centre point as it is the most sensitive and seems to be the most accurate.

It could alo be a front-focussing issue since in both shots the sharpest focus seems to be in front of your intended spot. If you want to test this, this link can help you out.

 

[mchhp]

You mentioned you are picking the focus point - definitely one focus point will be more accurate than leaving it in wide focus and letting the camera choose. A few things that might be causing minor issues:

1. Are you using the spot focus center point? Usually entry level cameras have a cross point sensor at least in the center, which is more sensitive and better to use for critical autofocus. Use a single point sensor and sometimes it can be off.

2. Are you firing the shutter quickly after achieving focus? And moreover, are you half-pressing to confirm focus first, then firing? Usually the best method is to half-press to achieve focus confirmation, then fire the shutter very quickly after - the more you delay, the more you can sway ever so slightly fore or aft, or the subject can move slightly, which can throw the focus off a touch.

3. Have you tested the lens you are using for front or backfocus issues? Importantly, you may want to test it at the apertures you most often use for portrait shots - try something like the 'battery' test - start with a wide-open aperture for the narrowest DOF, and shoot a lineup of AA batteries standing on end from a 45 degree angle. Have the camera on a tripod or steady on a table or wall so it can't move. Focus on the center battery, then see if the image looks accurate. If the focus is more on the 2nd battery foreward or back, then you may have a focus accuracy issue with the camera or that lens.

4. If all else fails, you could try manual focusing, or if your camera provides it, a direct or manual focus override, whereby you autofocus, then turn the focus ring to 'fine tune' the focus. Also, if your camera has live view with autofocus capability, you might try that - live view with a Canon is going to be slow, with a big delay for the shutter, but if your kids sit still for you for a few seconds to get the shot, it might still work OK - this can be a good test because the live view system may be using a different focus method - contrast-detection rather than phase-detection...see if again your PD focus system might be off a bit.

5. You may consider renting or borrowing a stabilized lens to test - just to eliminate that as a possibility. I don't know what shutter speeds you used in the above shots, but if they were under 1/250, and you had any vibration or unsteadiness, it could be just enough to affect the focus sharpness. However, in at least the daughter shot above, the focus seems to be very sharp but just in the wrong spot...so this is a less likely issue.

First off I am just so excited with all these wonderful responses!

1. I do mostly use the center focus. I have read about how some have a veritical sensor and some have horizontal and the center one has both. I have used others but the majority of the time it's the center

2. I do no recompose. I wouldn't even get close to focus doing that, lol. I do either hold the shutter down 1/2 way confirm and quickly fire. I also have it set up to back button focus and use that mostly

3. I have read and attempted doing the focus test with my lens, it totally confused me the first time and. Guess I should read some more and try again.

 

[wbeem]

One focus point is key, and you want that on the subject's closest eye, However, don't leave it in the center. Move it around to get the composition you want.

Something else that may happen is having your focus set to Continuous instead of Single mode. At least, that's something I have on my Nikon. I presume there's a comparable setting on your Canon. Basically, you want to set your focus with a half-press of the shutter and lock it. That happens on Single mode. A continuous mode would keep searching for something else to use as its focus point, despite what you want.

As for portraits, use something longer than a 50mm lens. It distorts facial features, pushes hairlines back, and other nastiness you probably don't want. I prefer 200mm when possible, but even 85mm is a good minimum.

 

[photo_chick]

As for portraits, use something longer than a 50mm lens. It distorts facial features, pushes hairlines back, and other nastiness you probably don't want. I prefer 200mm when possible, but even 85mm is a good minimum.

A normal 50mm is actually the closest to how our eyes see when it comes to lens distortion. Wider than 50mm tends to make things shorter and squattier and if you're close enough you get the bulging barrel distortions with wider angles. Longer than 50mm tends to make things taller and thinner and can visually compress the space. And when you're talking about this kind of distortion, crop really doesn't come into play a whole lot.

 

[wbeem]

A normal 50mm is actually the closest to how our eyes see when it comes to lens distortion. Wider than 50mm tends to make things shorter and squattier and if you're close enough you get the bulging barrel distortions with wider angles. Longer than 50mm tends to make things taller and thinner and can visually compress the space. And when you're talking about this kind of distortion, crop really doesn't come into play a whole lot.

Let's use visual aids.

 

[wbeem]

Here's a more dramatic example.

 

[wbeem]

This page gives more visual examples of the effects of focal length distortion on a human subject.

http://stepheneastwood.com/tutorials/lensdistortion/tilepage.htm

 

[boBQuincy]

Back to basics here, the lens focal length has nothing to do with perspective. Only the distance from the subject can change that. Obviously we change distance from a portrait subject according to the focal length but it still is not an effect of the lens.

 

[wbeem]

Bob,

Al of the examples I just showed were from the same perspective of the subject, but with a different focal length. Please explain your disagreement in the face of visual evidence to the contrary.