Not in focus

[bwilke]

I took some portraits of my daughters senior prom and i have nikon d80 with the 80-200 f/2.8 lens but many were very blurry...
I had it on AF-A and had my aperature set to 2.8 for the DOF......
Many pictures are very blurry but the focus had it locked in on the view finder...when reviewing the pics the shutter speed chosen by the camera was 60 with the set 2.8 aperature.....
If I put the camera on auto setting it would choose 2.8 with a 125 shutter speed..so I manually put it on both of those settings and the picture was better....

why does the camera choose shutter speed of 60 when I select 2.8 aperature.....
when in auto mode it selects the 125...

This is the second time I have taken portrait shots and many are blurry....what am i doing wrong...thanks.

[SmartWombat]

1/125 is too slow to stop movement, if it's candids, not posed "hold it" pictures, you will get blur.
It could be that Auto is also setting the ISO, or that what was in the scene changed, maybe more light from the background.
Using f/2.8 gets you more light, for a shorter shutter speed, but less DoF which makes the focus critical.

I guess that most of the problem is motion blur and camera shake, not focus.
Can you post some examples?

[bwilke]

I will try to post a few examples when I get home...
For the most part they were posed shots with her and her date.....I like the 2.8 for the shallow DOF and making the subject stand out but may need to change it to a smaller f stop...there was a good bit of light as we were taking the pics outdoors and the sun had not gone down. I was using green shrubs for the back drop.......may need to invest in a tripod to reduce the camera shake.......
I will try to upload a few pics later...thanks for your help....

[Frog]

I'm not an expert but 1/125 or even 1/60 with non moving subjects seems like it would be fine. Did you move the command dial when it was on Aperture priority?

[brmill26]

Based on your description, you're probably getting motion blur (camera shake). 1/60 is pretty slow for a non-stabilized 80-200 telephoto lens. There is a rule in photography that to avoid blur from camera shake, your shutter speed should match the focal length or higher. For example: if you're shooting at 50mm, you'd want at least 1/50 shutter speed; or if you're at 100mm, you'd want at least 1/100.

So applying this to your facts above, 1/60 is a little too slow even fully zoomed out to 80mm. Of course, at 200mm it becomes extremely difficult to get a sharp shot at 1/60, even for a very steady hand.

I'm guessing the reason it changed when you went to auto was because it also adjusted the ISO up. Since you can't go any wider than F/2.8 on the aperture, the only other way to get more light (w/o lowering shutter speed) is to raise the ISO. So, if you were in Aperture Priority mode shooting at F/2.8, what you would do is raise the ISO up in order to get a shutter speed that is at or above the focal length.

Even with the sun up, the camera sees a row of bushes as a pretty dark background. A very nice background for portraits to be sure, but fairly dark. Next time, watch your shutter speeds. If you see them at or below the focal length you're shooting, raise your ISO.

[Frog]

Good points Brad.
Now I have to go see if the iso changes when in aperture priority.

[Grandpaw]

Good points Brad.
Now I have to go see if the iso changes when in aperture priority.

Frog, it doesn't change the ISO in aperture priority unless you have it in AUTO ISO, Jeff

[Frog]

Thanks, Jeff. Yeah, I looked that up.
I don't use auto anything much except aperture priority sometimes so forget what each one does.

[bwilke]

All very good points and I will take a look to see what ISO it was choosing...I was in Aperature priority and since the sun was out, I think it was ISO 100 or 200....great feedback on the shutter speed and zoon length and one that I have not heard..thanks so much...I was actually confused as to why in aperature priority that it was selecting a 1/60th shutter speed, with the sun being out, but the dark back ground makes since......

so many things to take in consideration, but I now have some tools to play with...thanks.