D700 Focus issues? Help please!

[GrillMouster]

I think the problem I'm having is I have so many more choices, it's hard to keep it straight...

Another reason for moving AF to the back AF-ON button (I'm not meaning to harp on that, just pointing out that this greatly minimizes what I have to keep track of).

Let me see if I have this:
If S on the front is selected and the single small box is selected, no tracking is supposed to happen right?

Correct. Whatever focus point you select and only that point will be it.

If S is selected on the front and the middle box (cross hairs) is selected then I can select my point but it would possibly move to the next nearest sensor if my subject moved. Am I getting this?

Correct, if your Dynamic AF is set to 9, 21, or 51 focus points. AF-C would also work with those same Dynamic AF settings. Basically, if the camera senses that the subject may have moved, it will search the 9 (or 21 or 51 depending on what you set in the menu) focus sensors immediately surrounding the selected focus sensor. The fewer dynamic AF points you have set, the faster AF tracking will be. Unfortunately, the viewfinder doesn't show you which of those surrounding sensors it's actually using; only the original selected focus sensor is highlighted. However, I think if you have the "info" screen showing on the back I think it will show the surrounding dynamic AF points. If you're using the 51-point 3D setting (different from the normal 51-point setting), then tracking would only occur in AF-C, and the viewfinder would show you which sensor it's using (you called it "jumping around").

Reading (again) it seems I can only select a smaller # of focus points if I have the cross hairs selected. Otherwise, S front, S back gives me all 51 whether I want them or not.

No, the number of focal points that you're able to select are determined by a completely different menu setting (a8). This makes it so that you either have 11 or 51 focus points to scroll through in both of the bottom settings on the back (crosshair and single). For speed I prefer to only have 11 available for me to scroll through. All 51 focus points are still available to the camera if tracking is enabled.

Have you gone bonkers yet?

Like I said above, my settings give me maximum flexibility with minimal thought or memorization of all these options.

 

[wenrob]

Yep I've officially lost my mind! Haha!
Gotcha I'll set it to 11 and see how that works for me. I'll also give the AF-On button a whirl and see what that gets me.
I'll report back and let you know what happens. Not tonight though, too much swimming through my brain. Plus my models are done for the day.
Thanks again!

 

[photo_chick]

On depth of field... here is an interesting thing I came across. I like the images he has that compares DoF on crop vs DoF on full frame.

http://www.have-camera-will-travel.com/field_reports/full_frame_vs_crop_sensor_-.html

 

[wenrob]

On depth of field... here is an interesting thing I came across. I like the images he has that compares DoF on crop vs DoF on full frame.

http://www.have-camera-will-travel.com/field_reports/full_frame_vs_crop_sensor_-.html

Thank you for that.

 

[GrillMouster]

The problem with that link is that he's comparing different fields off view. Depth of field is affected by aperture, focal length, and camera-subject distance. Because a full-frame body gives a wider view, you have to get closer to achieve the same field of view as you would get with a crop-sensor body. Because you're closer, you get shallower depth of field. I understand his point that it's not the camera itself that is causing a difference, but I think he's being a bit too literal. In the real world, a person photographing a head and shoulders portrait with a crop body, who then switches to a full frame body would step forward to get the same framing. He/she wouldn't just stand in the same spot and settle for a full body portrait when (s)he wanted a head and shoulders portrait.

 

[wenrob]

The problem with that link is that he's comparing different fields off view. Depth of field is affected by aperture, focal length, and camera-subject distance. Because a full-frame body gives a wider view, you have to get closer to achieve the same field of view as you would get with a crop-sensor body. Because you're closer, you get shallower depth of field. I understand his point that it's not the camera itself that is causing a difference, but I think he's being a bit too literal. In the real world, a person photographing a head and shoulders portrait with a crop body, who then switches to a full frame body would step forward to get the same framing. He/she wouldn't just stand in the same spot and settle for a full body portrait when (s)he wanted a head and shoulders portrait.

This makes sense. Really, it's all about me learning the camera I think. DH reminded me how frustrated I was when I first moved from a PnS to the D40 and then again to the D90. I just need someone to turn these kids into cooperative angels that need nothing more then to pose for Mama.

 

[pjacobi]

The best way to improve these sample photos would be to use an external flash bounced off the ceiling. That way, you will be shooting at f/8 which will eliminate focus and depth-of-field issues.

-Paul

 

[wenrob]

The best way to improve these sample photos would be to use an external flash bounced off the ceiling. That way, you will be shooting at f/8 which will eliminate focus and depth-of-field issues.

-Paul

Why would I shoot f/8 with a flash? I'm well versed in using a flash but part of the reason for this camera is it's high ISO capability and my desire to move away from the flash a bit. Admittedly those shots could use a flash and/or more attention to exposure but I was simply taking them to show what I was talking about.
I think GrillMouster and I have narrowed it down to my focus technique and a bit of DoF issue.

 

[GrillMouster]

Your primary concern has been that focus seem to be shifting from your intended subject to the other. We've discussed why that may be happening. However, even if you were able to solve that problem you'd probably still only have one, not both, subjects in focus. So your depth of field is too narrow for this particular situation. One way of increasing depth of field, as previously touched upon, is stepping further away from the subjects and using a longer focal length to achieve the same framing. For example, instead of standing three feet away at 70mm, stand six feet away at 140mm. Your depth of field would go from one inch to almost one foot.

Another way to increase your depth of field is to use a smaller aperture. Adding light to the scene would allow you to use a smaller aperture and maintain exposure. You can add light by using a lamp, reflector, moving the subjects closer to a window, or, as pjacobi suggested, by using flash (f/8 not necessary). Instead of, or addition to adding light, you can use a slower shutter speed to allow light to hit the sensor for a longer period of time. Another option is to increase the ISO sensitivity. Your camera in particular has excellent high ISO performance. You could have easily increased the ISO and stopped down the aperture to get more of the scene in focus.

Is there a reason you're set on using f/2.8? I find that many amateurs are getting caught up in some kind of fad of always using the maximum aperture without really understanding why. There should ALWAYS be a reason for the settings you choose. In portraiture, shallow depth of field is usually desired so that the subject stands out and so that the background and distracting elements (that haven't already been de-emphasized through angle, composition and lighting) can be minimized by blurring them out. You can achieve that goal with aperture settings of f/3.5, f/4, and even f/5.6. Sometimes f/2.8 is "too much of a good thing". You don't always have to aim for the shallowest depth of field possible; you should aim for the shallowest depth of field NECESSARY.

 

[wenrob]

Grillmouster, I'm well aware of all of that. It seemed he was suggesting f/8 as a flash setting which I didn't get.
I'm used to nailing focus on 3 kids at f/2.8 eight out of ten times which is the only reason why I started there. That's why I went ahead and closed down to f/4.5 and f/3.5 on the other test shots thinking it was more then enough. As has been discussed that's not quite enough for the D700. It's just going to take some practice to get to know the camera. I do know how to get proper exposure and I more then understand what I need to do and why. Those pics don't reflect that but at the time my concern was that there may be something wrong with the focus. You've talked me through that and I plan on putting what we've discussed into practice.

eta:the pics with my DH I did use a flash.

 

[wenrob]

One of the first test shots after I started thinking DoF may be the cause:
f/4.5 ISO 800 SS 160, SB600 bounced off a wall to my right.

I chose those settings as I wanted the flash to not have to work as hard and my SS over 100 because they're kids, they move! I was a good five feet from them, zoomed to 62mm. This is when I started to think it was a focus issue as the focus spot hits DS's hair where it meets DD's hair yet DD is sharp and focus falls off of DS(though not as bad as the others). I'm used to focus falling off both sides not one side or the other.

I guess I'm just saying I'm aware of exposure and flash and how to use them to my advantage. The only thing I did to these pics was contrast, color and WB, my exposure was not tweaked. It seems I'm not aware of just how different the DoF is on the D700 or how much more sophisticated the focus system is. On the D90 I would have them both sharp at f/2.8 easy.

 

[pgowder]

Hold on; you keep saying that the AF is "favoring" DD, so you're letting the camera determine where it focuses? You're not tracking birds or fast-moving subjects. With reasonably static subjects, just use single-point AF, no tracking. You can move the focus point to where you want it. If you're using the center focus point and recomposing it could be trouble at really wide apertures.

If I'm shooting portraits with the D700 I always use the single point and place it where I want it.

There may be other ways to do it. But using the single point, you know for sure you got it!


Christmas Portrait by Paul Gowder, on Flickr
f2.8 @ 135mm