Help me focus properly

[thestrangebrew1]

This weekend I took my camera to take some pictures at a graduation party. I primarily used an 85mm lense. I noticed that on some photos like the one below, only portions of the frame look sharp and focused to me.



The pic above, the two men on the left and the girl standing look pretty sharp, but the woman sitting and the two other men on the right look blurry.

Is this a lense issue or a camera setting? I don't have my camera on my so I don't remember the settings, and I know how to use the focus points where you select what you want to focus on but for these bigger group photos, what would be the best settings to use to focus properly?

 

[EOM]

Dirty lens? I was originally suggesting shallow DOF but maybe not? What was your aperture?

 

[thestrangebrew1]

Dirty lens? I was originally suggesting shallow DOF but maybe not? What was your aperture?

I'll have to check but I think it was at 2.8. Not at home right now.

 

[Syborg1211]

Looks to me like the guy in the bottom left is the only one fully in focus. This looks like too shallow depth of field to me. An 85mm at f/2 on a full frame sensor at 10 feet away will have a depth of field of 6 inches, 8 inches at f/2.8.

Unfortunately for group photos with a big sensor camera, you have to stop down pretty far or very carefully make sure everyone is on the same plane to get everyone in focus. It's one of the unspoken advantages that phones and small sensor cameras have over big cameras - bigger depth of field for group or landscape photos.

 

[CuriousMike]

Looks to me like the guy in the bottom left is the only one fully in focus. This looks like too shallow depth of field to me. An 85mm at f/2 on a full frame sensor at 10 feet away will have a depth of field of 6 inches, 8 inches at f/2.8.

Unfortunately for group photos with a big sensor camera, you have to stop down pretty far or very carefully make sure everyone is on the same plane to get everyone in focus. It's one of the unspoken advantages that phones and small sensor cameras have over big cameras - bigger depth of field for group or landscape photos.

I don't have much to add because Syborg pretty much nailed it. Infuriatingly, your photo hosting service doesn't provide EXIF data so there's no way to easily see what your aperture was, but the supposition that its wide open is the most reasonable explanation for this.

Group photo like that, minimum f/8 and focus about 1/3 into the scene. Don't pick the person in front, don't pick the person in back. Typically, you have more depth going back then forewards.

For a shot like the above, I'm all about f/8 with a 1/(2xfocal) length shutter speed ( 85mm? = 1/200 ) and auto-ISO.
In that light, you might have been ISO 800? You can fix a little grain, you can't fix a lotta blur.

 

[thestrangebrew1]

After thinking about it and watching some videos of DoF, I think this is definitely what the problem is. I'm always concerned with exposure when taking shots that I've completely forgotten about aperture. Mostly my lack in practicing the last few months. I'm usually setting the camera on manual, so I think I need to go back to the drawing board and get accustomed to messing with the aperture as well. Maybe just set it to aperture priority and take a bunch of shots with my current lenses to see the differences to get a better understanding of my gear.

 

[CuriousMike]

After thinking about it and watching some videos of DoF, I think this is definitely what the problem is. I'm always concerned with exposure when taking shots that I've completely forgotten about aperture. Mostly my lack in practicing the last few months. I'm usually setting the camera on manual, so I think I need to go back to the drawing board and get accustomed to messing with the aperture as well. Maybe just set it to aperture priority and take a bunch of shots with my current lenses to see the differences to get a better understanding of my gear.

If you're not familiar with your cameras focusing modes, you should look into that as well.
If you were controlling the focus point and had a shallow DoF, I would have expected one of the people in the middle to be in focus. My guess is you're in auto-AF and the AF system chose the person in the bottom left to focus on.

If you're a Canon shooter, I think their software has an option to show you which focus point was used. You should also check into that as it could definitively show the issue.

Alternatively, there is a plug-in for LR that shows the focus point used.

i.e.,

 

[thestrangebrew1]

If you're not familiar with your cameras focusing modes, you should look into that as well.
If you were controlling the focus point and had a shallow DoF, I would have expected one of the people in the middle to be in focus. My guess is you're in auto-AF and the AF system chose the person in the bottom left to focus on.

If you're a Canon shooter, I think their software has an option to show you which focus point was used. You should also check into that as it could definitively show the issue.

Alternatively, there is a plug-in for LR that shows the focus point used.

i.e.,

This is great info thanks! I'll look into installing that plug-in. As far as the EXIF data, what image hosting site shows that info?

 

[CuriousMike]

This is great info thanks! I'll look into installing that plug-in. As far as the EXIF data, what image hosting site shows that info?

flickr does for sure. A lot of other sites must because most of the photos I see posted here have the EXIF intact. Whichever program you use to export your photos, be sure it isn't stripping out the EXIF data ( unless you want to ).

 

[thestrangebrew1]

Ah ok. I have a flickr acct so I'll upload them there and make sure the data is available next time.

 

[Syborg1211]

After thinking about it and watching some videos of DoF, I think this is definitely what the problem is. I'm always concerned with exposure when taking shots that I've completely forgotten about aperture. Mostly my lack in practicing the last few months. I'm usually setting the camera on manual, so I think I need to go back to the drawing board and get accustomed to messing with the aperture as well. Maybe just set it to aperture priority and take a bunch of shots with my current lenses to see the differences to get a better understanding of my gear.

Don't let this instance of not getting your intended final photo discourage you from manual control. In the end, you learned a lesson and know now to raise the aperture to increase the depth of field and get more stuff in focus. So now you know next time to bump the aperture for a group photo. This is how we all learn photography - trial and error. Learn from the lessons and eventually you'll know better than any auto mode what settings your intended shot is.

 

[Rifter]

You need to be careful with AF, it does stupid things like pick the wrong person to focus on like in your example. And i wouldn't shoot that scene wide open it will be much harder to get in focus if its even possible, try stepping down till you can get what you need in focus.

I sometimes still use AF but only with lens that will allow you to manually adjust the focus even with AF enabled, this allows you to easily correct situation like yours with just a quick turn of the focus ring, because even if AF fails to target what you want its usually very close and easy to manually correct. If my lens locks out the focus ring in AF mode i will always just manually focus. Just my opinion.

 

[myocardia]

...

 

[Rifter]

What an utterly gorgeous photo. You should be famous by now, if any percentage of your photos are half this good. I have a question for you about this photo. Maybe the answer will help the OP.

I looked your camera up online, and the review said it has 39 (!!!!) focus points. Does someone wanting to take a picture as gorgeous as this one, that is completely focused from edge to edge in both directions, with a dSLR as nice as yours, have to manually set 39 focus points, (or however many their particular camera can pull off)? Also, does using any amount of optical zoom affect picture quality any at all?

39 focus points just means the AF will look at 39 points in the frame to try and figure out what you are trying to focus on, my camera has 11 focus points. If you are focusing manually the number of focus points is completely irreverent as they will not be used.

Optical zoom will generally not degrade your picture much at all, this is why people spend money on zoom lens instead of just using digital zoom.

Every lens has a "sweet spot" in its zoom range that it will take its best pictures in, but this is generally not noticeable unless you really look for it with editing tools. My 70-300mm lens for example tends to take the best pictures around the 150-200mm zoom range. But you would be hard pressed to tell the quality difference between a picture of the same object taken at 70mm and 300mm.

 

[CuriousMike]

Does someone wanting to take a picture *snip* that is completely focused from edge to edge in both directions, with a dSLR *snip* have to manually set 39 focus points

Thanks again for the compliment. They say "If you want to take a beautiful photo, point your camera at something beautiful."

1. DSLR's focus systems have a bit more flexibility than other kinds of cameras.

One part of the flexibility is the concept of focus points -
Shown below is a camera with 9 focus points, and the person taking the photo can use the directional-pad on the back of the camera to move the red box around to any of the 9 focus points and telling the camera "FOCUS ON THIS"

Often times, new DSLR owners will leave their camera in "auto focus", where the camera will use the available focus points to determine what it thinks is the subject you want in focus. It can use multiple focus points to come up with its best guess. But... it's a guess. When you switch the DSLR's focus mode to point-selection mode, you will never have an out of focus subject because YOU are controlling where one of those focus points lands.

2. Zoom lenses do affect quality. Generally speaking, a prime lens ( it does not zoom ) has a sharper image. However, nowadays, most modern zoom lenses are sharp enough throughout their range. Any issues are usually correctable by software. 90% of my photography is with a zoom lens - they simply offer too much flexibility when in the field to ignore. If I *know* I'm going to do something specific, I have specialty prime lenses to cover those cases. For example, I have a portrait lens and an astrophotography lens.

Edit: Also, http://forums.anandtech.com/showthread.php?t=2456579

 

[myocardia]

...

 

[CuriousMike]

Wow, that was very informative, Rifter. Thank you. Does that mean then that the reason that the picture in CuriousMike's screenshot was so focused from edge to edge to edge is because he used the proper ISO and aperture settings for that lens, and for that location/setting?

Depth of Field ( how much is focused from the front of the scene to the back of the scene ) is a function of aperture and distance to the subject. ISO has no bearing on what is in focus.

For reasons I don't fully understand, smaller sensor cameras ( think smartphone ) generally have a larger depth of field ( more is in focus ) than larger sensors. Generally, it's harder for a smartphone to have out-of-focus areas of an image than a larger sensor DSLR.

Put another way, it's often difficult with a large sensor camera to have an entire scene perfectly in focus.

The reason my photo looks to be in clear focus from the rocks in front to the mountains in back is a function of the fact that the rocks are actually somwhat distant in front of me and I focused about 1/3 into the scene. If I needed more foreground in focus, I would have had to use a smaller aperture than I did.

 

[guachi]

If your camera has facial recognition as a focus option, you might try that. If the camera can tell where the faces are the AF will likely try to keep them all in focus.

Alternatively, manually stop the aperture down like others have suggested and you'll probably have good results.

I guess it could be a problem with PDAF causing front or back focus issues, though I doubt that's the case here.

 

[CuriousMike]

If the camera can tell where the faces are the AF will likely try to keep them all in focus.

*I don't understand how this works (keeping multiple faces in focus.)

There is only one focal plane.

Does the camera determine the DoF, and attempt to automagically calculate which focal plane to focus on, then pick the aperture that will most closely try to cover the other face-focal-planes?


*Nor do I understand the more common auto-focus, where your camera will light-up multiple focus points when it finds "auto focus".

 

[Syborg1211]

*I don't understand how this works (keeping multiple faces in focus.)

There is only one focal plane.

Does the camera determine the DoF, and attempt to automagically calculate which focal plane to focus on, then pick the aperture that will most closely try to cover the other face-focal-planes?


*Nor do I understand the more common auto-focus, where your camera will light-up multiple focus points when it finds "auto focus".

I know with the multiple focus points like the awesome group focusing option on the D810 (sigh sooometimes I miss my D810) it always picked the closest focal point. So if the grouped points were put over someone's face, it would focus on the nose since it's the closest. This did lead to some front focus issues when using this mode (maybe I don't miss it that much).

No clue about the facial recognition since I never used that. I would say taking control of the focal point (not necessarily manually racking the focus but choosing the focus spot) is the most important thing for anyone using a camera to learn. I can forgive people for not wanting to or being able to learn the exposure settings, but the focal point control is an absolute must. If you don't even know what you want to take a picture of, then don't even take the picture.

The whole point of a photograph is to show people your perspective at that very moment, and the camera can't read your mind on what your eyes are locked in on in the scene.

 

[CuriousMike]

I can forgive people for not wanting to or being able to learn the exposure settings, but the focal point control is an absolute must.

Canikon needs a sticker over the back LCD screen that is text for a short-url to a youtube video that says, "Congratulations on your new DSLR. Here's how to focus."

 

[Rifter]

wow, that was very informative, rifter. Thank you. Does that mean then that the reason that the picture in curiousmike's screenshot was so focused from edge to edge to edge is because he used the proper iso and aperture settings for that lens, and for that location/setting?

sorry thought you said op pic disregard original reply...

And yes he used perfect settings, DSLR's are fairly smart nowadays, you dont need to go pure maunal most of the time, you can go appurture or shutter mode and based on what you tell it it will generally then pick the correct settings to go with it based on light levels and whats in the scene.

 

[Rifter]

No clue about the facial recognition since I never used that. I would say taking control of the focal point (not necessarily manually racking the focus but choosing the focus spot) is the most important thing for anyone using a camera to learn. I can forgive people for not wanting to or being able to learn the exposure settings, but the focal point control is an absolute must. If you don't even know what you want to take a picture of, then don't even take the picture.

The whole point of a photograph is to show people your perspective at that very moment, and the camera can't read your mind on what your eyes are locked in on in the scene.

Agree completely, its why i ended up with so many lens, some are better than others for certain distances/situations. I absolutely love my 35mm prime for low light situations, But the 18-85mm is so versatile. cant have just one lens lol.

 

[Rifter]

Canikon needs a sticker over the back LCD screen that is text for a short-url to a youtube video that says, "Congratulations on your new DSLR. Here's how to focus."

I learned to distrust autofocus fairly quickly and use manual most of the time, or if i have time with the shot ill give AF a shot at it and manually tweak if needed.

 

[CuriousMike]

I learned to distrust autofocus fairly quickly and use manual most of the time, or if i have time with the shot ill give AF a shot at it and manually tweak if needed.

Don't get me wrong - I use auto-focus 99% of the time. What I'm saying is if you use single-point auto-focus, you control where the camera focuses and its much more reliable than auto-area/automatic AF point selection.