nifty fifty focus help

[Stephanie Cole]

Hi everyone! I just got the nifty fifty f1.8 as an early Christmas present and I've been loving it so far! The only thing I've been noticing though is when I go to take a picture and I have the center dot focused where I want it, that part comes out a little blurry and just below it's focused. If what I said doesn't make since then please look at the attached picture. You can see the baby's head is what I intended to focus on but it came out soft and the sweater came out in focus. This is a little aggravating but I'm hoping someone can help me out. I've tried using the focus dial next to the eye piece and that's it.

Thanks again for the help!!

 

[gsgary]

It all looks out of focus probably due to shutter speed too low

 

[memento]

You missed your focus point.. which should be the eyes.
Either a bigger aperture or better attention to focus point.

 

[Stephanie Cole]

You missed your focus point.. which should be the eyes.
Either a bigger aperture or better attention to focus point.

I will try again, once I started noticing I was trying to do that but it still seemed off to me. f1.8 is the largest I can go. And you can see too that the blanket looks focused and that's in the bottom corner.

 

[waday]

Providing some EXIF data (i.e., shutter speed, aperture, ISO) may help generate responses.

Other than that, you said your center dot. It looks like the center dot would be placed near the neck of sweater, which appears to be more in-focus than the rest. Did you focus and re-position the picture?

If you're shooting at a wide open aperture (e.g., f/1.8), you're going to see a very thin/shallow depth-of-field and anything on this plane will be in focus but anything outside will be out-of-focus. This is why the neck of the sweater, button, and portions of the blanket are in focus. They are most likely in the same plane as what was focused. Anything outside, for example, the face, will be out-of-focus.

The "focus dial next to the eye piece" is the diopter adjustment. Watch this video to set this:

 

[astroNikon]

what kind of camera do you have?
Also, what focusing mode are you using?

If you are in an auto focus mode you would be allowing the camera to find the most contrasty area available in it's focus point area, which could be the sweater. Thus it could focus on the sweater versus the face.

If you are in a Single Point focus mode and are focusing on an eye, then that is a separate problem..

 

[Designer]

I will try again, once I started noticing I was trying to do that but it still seemed off to me. f1.8 is the largest I can go. And you can see too that the blanket looks focused and that's in the bottom corner.

When the aperture is open that much, and you're only aa couple of feet from your subject, the depth of field (DOF) is probably in the neighborhood of one inch. ONE INCH!!!! Or not much more than that.

That is why you see the fabric in focus, but the face is not. Now if you were to get out a scale (tape measure) and measure the distance from the camera to everything you want in focus, I'll bet that you're going to find the DOF needs to be more like 12 inches. Not 1 inch.

SO, now... how to do this photograph? You have some options, so the first thing you should consider is to simply move your little self around so that the baby's face is about the same distance from the camera as his sweater, and hands, and hair, and ... well, you get the idea. Have everything the same distance. I know that's probably not realistic, but at least now the critical areas are not 12 inches, but more like 6 inches.

Now you can stop the lens down to say; f/4 or f/8 to get a deeper DOF. Maybe you need even more like f/16. Whatever. Now you see how the aperture affects the DOF.

Your next hurdle is to make a good exposure using that aperture.

Here again you have some choices. Since I assume you are hand-holding the camera, you shouldn't extend the shutter time much beyond 1/50 of a second. If that works, then fine; snap away.

If not, adjust the sensitivity to ISO 400, or ISO 800, or whatever it will take to get that exposure.

Oh, poop! The baby needs a change. Just when you were ready to take the picture, too. Oh, well, there's always tomorrow.

 

[480sparky]

50mm.

DX format

f/1.8.

Focused at 24"


DOF is 0.36". 1/3 inch.

 

[Mr.Photo]

As everyone else has mentioned shooting a 1.8 aperture lens wide open and at close distances results in a very narrow depth of field meaning you have to be very specific with your focus point, and have either a very steady hand or a tripod to keep the camera from shifting forward or backwards. I actually found that when shooting hand held, after locking focus and recomposing the shot I had a tendency to lean forward about 1/4 inch which caused me to miss focus making the area behind where I thought I was focused sharp. In this case it's a possibility that once you locked your center focus point on her face, when recomposing the shot you may have leaned back slightly which caused the sweater to be the point in focus.

Another small possibility that sometimes occurs is that your particular lens may be mis-calibrated causing an issue known as either back focus or front focus. This can only be tested properly using a tripod, and preferably a focus calibration device such as the Spyder LensCal.

 

[Designer]

50mm.

DX format

f/1.8.

Focused at 24"


DOF is 0.36". 1/3 inch.

I didn't bother plugging any actual values, just a SWAG. Even thinner that I had guessed.

 

[Stephanie Cole]

I will try again, once I started noticing I was trying to do that but it still seemed off to me. f1.8 is the largest I can go. And you can see too that the blanket looks focused and that's in the bottom corner.

When the aperture is open that much, and you're only aa couple of feet from your subject, the depth of field (DOF) is probably in the neighborhood of one inch. ONE INCH!!!! Or not much more than that.

That is why you see the fabric in focus, but the face is not. Now if you were to get out a scale (tape measure) and measure the distance from the camera to everything you want in focus, I'll bet that you're going to find the DOF needs to be more like 12 inches. Not 1 inch.

SO, now... how to do this photograph? You have some options, so the first thing you should consider is to simply move your little self around so that the baby's face is about the same distance from the camera as his sweater, and hands, and hair, and ... well, you get the idea. Have everything the same distance. I know that's probably not realistic, but at least now the critical areas are not 12 inches, but more like 6 inches.

Now you can stop the lens down to say; f/4 or f/8 to get a deeper DOF. Maybe you need even more like f/16. Whatever. Now you see how the aperture affects the DOF.

Your next hurdle is to make a good exposure using that aperture.

Here again you have some choices. Since I assume you are hand-holding the camera, you shouldn't extend the shutter time much beyond 1/50 of a second. If that works, then fine; snap away.

If not, adjust the sensitivity to ISO 400, or ISO 800, or whatever it will take to get that exposure.

Oh, poop! The baby needs a change. Just when you were ready to take the picture, too. Oh, well, there's always tomorrow.

Thanks! These are all things I'm taking into consideration. It's a learning process!

 

[Stephanie Cole]

As everyone else has mentioned shooting a 1.8 aperture lens wide open and at close distances results in a very narrow depth of field meaning you have to be very specific with your focus point, and have either a very steady hand or a tripod to keep the camera from shifting forward or backwards. I actually found that when shooting hand held, after locking focus and recomposing the shot I had a tendency to lean forward about 1/4 inch which caused me to miss focus making the area behind where I thought I was focused sharp. In this case it's a possibility that once you locked your center focus point on her face, when recomposing the shot you may have leaned back slightly which caused the sweater to be the point in focus.

Another small possibility that sometimes occurs is that your particular lens may be mis-calibrated causing an issue known as either back focus or front focus. This can only be tested properly using a tripod, and preferably a focus calibration device such as the Spyder LensCal.

That very well could be what is happening because I was crouching on my feet. I should have tried a different aperture.

 

[astroNikon]

read this about Depth of Field ==> Understanding Depth of Field in Photography

then start taking measurements and see what Depth Of Field (DOF) you get based on the distance to the subject, aperture, camera & lens ==> Online Depth of Field Calculator

you'll learn that f/1.8 really isn't good in general for general people photography. f/5.6 and higher normally is, but dependent upon the "depth" of focus you need based on the distance to the subject etc

It's fun learning about all this stuff ... alot more complicated than I thought when I got going.