Further questioning.

[AMOMENT]

Is it true that if I use an auto select focus point other than the center one, that it is more likely that less of my photo will be in focus even with the same DOF calculation? (because of cross points?)

Someone had recommended using my center focus point to focus, and then recomposing so that the person's eye was in focus in th right positon. Usually, if your subject is in the center of a frame (given that's how you want the composition), then to completely nail the eye, you would have to select a focus point slightly left or right. Right? If I select my central point, depress to do so, and then move my camera at all it will be out of focus. So, how is that I should most often use my center point if I want to nail the focus on someone's eye?


I can't read my manual because I don't have it anymore. It got lost during a move. I'm sure I can order a new one but until then, maybe you guys can help since you know so much.


This whole focusing and then recomposing is confusing me. To compose a shot you need to depress the shutter to lock focus. If you move the camera or the subject moves at all, unless you are using tracking, then your subject will be out of focus. I'm frustrated. I know there is alot I should be reading and I'm working on getting the books. I really appreciate everyone's time in explaining. I know this is all basic stuff to you but I am just starting.

 

[tevo]

Is it true that if I use an auto select focus point other than the center one, that it is more likely that less of my photo will be in focus even with the same DOF calculation? (because of cross points?)

Someone had recommended using my center focus point to focus, and then recomposing so that the person's eye was in focus in th right positon. Usually, if your subject is in the center of a frame (given that's how you want the composition), then to completely nail the eye, you would have to select a focus point slightly left or right. Right? If I select my central point, depress to do so, and then move my camera at all it will be out of focus. So, how is that I should most often use my center point if I want to nail the focus on someone's eye?


I can't read my manual because I don't have it anymore. It got lost during a move. I'm sure I can order a new one but until then, maybe you guys can help since you know so much.


This whole focusing and then recomposing is confusing me. To compose a shot you need to depress the shutter to lock focus. If you move the camera or the subject moves at all, unless you are using tracking, then your subject will be out of focus. I'm frustrated. I know there is alot I should be reading and I'm working on getting the books. I really appreciate everyone's time in explaining. I know this is all basic stuff to you but I am just starting.

Set up back button focus. That way, you can press your AE-L/AF-L button to focus, then when you recompose and press the shutter, it will not re-adjust the focus point.

 

[LightSpeed]

Did this really need another 2 threads?

I find that one must manually focus, at times, for composition purposes.
In other words you must trust your eyes and not a beep from the camera.
You also might check to make sure your view finder is in focus.
One must also realize that not everything you do with a camera should be automatically done for you.

 

[tevo]

Also, here's the D3100 manual in PDF form.

http://www.nikonusa.com/pdf/manuals/noprint/D3100_ENnoprint.pdf


(would recommend saving this one to your computer or printing it - takes a few minutes to load it up online)

 

[LightSpeed]

Is it true that if I use an auto select focus point other than the center one, that it is more likely that less of my photo will be in focus even with the same DOF calculation? (because of cross points?)

Someone had recommended using my center focus point to focus, and then recomposing so that the person's eye was in focus in th right positon. Usually, if your subject is in the center of a frame (given that's how you want the composition), then to completely nail the eye, you would have to select a focus point slightly left or right. Right? If I select my central point, depress to do so, and then move my camera at all it will be out of focus. So, how is that I should most often use my center point if I want to nail the focus on someone's eye?



I can't read my manual because I don't have it anymore. It got lost during a move. I'm sure I can order a new one but until then, maybe you guys can help since you know so much.


This whole focusing and then recomposing is confusing me. To compose a shot you need to depress the shutter to lock focus. If you move the camera or the subject moves at all, unless you are using tracking, then your subject will be out of focus. I'm frustrated. I know there is alot I should be reading and I'm working on getting the books. I really appreciate everyone's time in explaining. I know this is all basic stuff to you but I am just starting.

Set up back button focus. That way, you can press your AE-L/AF-L button to focus, then when you recompose and press the shutter, it will not re-adjust the focus point.

Good recommendation, but, it doesn't take much movement to bring something out of focus that you wanted in focus during the composition, I've found.

 

[shootermcgavin]

I think you are over thinking it, your focusing is not bad. You pick a point of where you want to focus and then click the button. If you are selecting auto focus or letting the camera pick the point then yes that is not a great way to focus. If I'm taking a portrait of someone most likely I am using the furthest left focus point or ones near it so I can focus on the eye. The middle focus point is supposed to have the best sharpest focus point so if you don't mind cropping then that's a good one to go with but not necessary.

 

[BlackSheep]

I can't read my manual because I don't have it anymore. It got lost during a move. I'm sure I can order a new one but until then, maybe you guys can help since you know so much.

I have no advice on your focusing questions (don't shoot Nikon), but did want to let you know that you can download a copy of your manual online, there's probably several different websites to get it from, but a quick google gave me this link:

User's Manual - D3100 - Guide to Digital Photography

Hope that helps!

ETA whoops sorry just realized that someone else beat me to it!

 

[tevo]

I can't read my manual because I don't have it anymore. It got lost during a move. I'm sure I can order a new one but until then, maybe you guys can help since you know so much.

I have no advice on your focusing questions (don't shoot Nikon), but did want to let you know that you can download a copy of your manual online, there's probably several different websites to get it from, but a quick google gave me this link:

User's Manual - D3100 - Guide to Digital Photography

Hope that helps!

ETA whoops sorry just realized that someone else beat me to it!

 

[AMOMENT]

okay so in my camera now and working with the AE-L and AF-L button settings. ae/af lock, ae lock, af lock, ae lock (hold) , af on, ae lock. What should I select?

I almost always, for now, want to get my focus on the left or right eye of a person which, also for now, is either somewhat left or right of center point or far left or far right. Therefore, I am selcting a left or right auto focus point. I can opt for dynamic area auto focus so that my camera will take in the points closest to it or om importance. I think, unless I am doing a portrait, I should use
AF-C.

I know someone said my focus doesn't seem off, and yet, I haven't posted some photos because my focus was so bad.

Going to dl the manual tonight while asleep. Thanks!!!! You guys are seriousely awesome and so kind!

 

[tevo]

okay so in my camera now and working with the AE-L and AF-L button settings. ae/af lock, ae lock, af lock, ae lock (hold) , af on, ae lock. What should I select?

I almost always, for now, want to get my focus on the left or right eye of a person which, also for now, is either somewhat left or right of center point or far left or far right. Therefore, I am selcting a left or right auto focus point. I can opt for dynamic area auto focus so that my camera will take in the points closest to it or om importance. I think, unless I am doing a portrait, I should use
AF-C.

I know someone said my focus doesn't seem off, and yet, I haven't posted some photos because my focus was so bad.

Going to dl the manual tonight while asleep. Thanks!!!! You guys are seriousely awesome and so kind!

You want to set "AF On" to your AE-L/AF-L button.

 

[tevo]

Also - it's not that your focus is bad.. here's an example:

http://www.thephotoforum.com/forum/...photo-gallery/229819-close-up-my-dog-c-c.html


That was from forever ago, when I first got my camera. The focus was on the nose (autofocus S, not the eye. You can see how it affects the photo; you want the focus to be on the eye.

 

[MLeeK]

I think what you are referring to is the fact that the cross type focus points are stronger. As long as you are in good light, the NON cross type points will be just fine. If you are having trouble in low light, then you want to switch to a focus point that is cross type.

When it comes to focusing and then moving to recompose the shot it's something you really don't want to do unless you absolutely have to and you especially don't want to do it when you are using a wide open aperture. The depth of field on a wide aperture is very small. If you think about the way your body turns side to side... Your nose starts out in the furthest forward point of your body, but as you turn to the side it becomes in line with other parts of the body until maybe it's behind your shoulder... Your camera is the same as the nose. As you turn it moves in relation to the subject too. Maybe not much at all, but at wide apertures if you move a 1/4 inch it matters. A LOT.
Because of that movement you want to toggle to the focus point that naturally falls on the eye or the spot you want to be in focus and use that.

As to where to focus you want to focus on the inside corner of the eye closest to you as your focus falls more backward than forward.

 

[KmH]

I think what you are referring to is the fact that the cross type focus points are stronger.

Cross-type focus points aren't stonger, but they can detect contrast in 2 directions, both vertical and horizontal.

Regular focus points only detect contrast in one or the other direction, either vertical, or horizontal, but not both.

Some cross-type focus points are calibrated to work well with wide apertures, like the Canon 7D's center cross-type focus point being calibrated for f/2.8 while the other 18 focus points the 7D has are all regular cross-type focus points.

 

[MLeeK]

Ok, my wording is off... Not sure how else I'd say that they are able to detect the contrast better than a non cross type focus point without going into the whole explanation you did...

 

[cgipson1]

And stick to F8 and above....

Question.. if you focus on someone with the center focus point, and DONT recompose... is what you focused on in focus? If not.. (assuming adequate DOF, and a fast enough shutter speed).. you have other issues.

If you have adequate DOF, the re-composing should not be an issue.

TEST: stand 10 feet away from subject on Brigh Sunny Day... set aperture to F16, in Aperture Priority. Set ISO to whatever is needed for a shutter speed of 125 or so. Focus on eye.. shoot without recompose. Now focus on eye, and recompose... shoot. Compare photos... both should be sharp (and you just moved the camera)! Now try the same thing at F 1.8 (or 2.8)..... neither will be sharp except for a very thin DOF area, that will probably not cover the area you wanted sharp... so the whole thing looks out of focus.

you CAN move the camera and still maintain sharp focus, as long as two things occur (assuming no body / lens issues)

1. Adequate DOF (to cover any movement of the camera from the plane of original focus, and to adequately cover the subject)
2. Adequate shutter speed.