Help, Why are some images Tack Sharp? And some are not?

Hello,

I am new to this forum and could really use some help. I generally photograph newborns, children and families and what I am struggling with is getting all my images tack sharp. I shoot both in studio and outdoors and have the same problem regardless of location. I am currently back button focusing (don't see the benefits in studio) and I manually select my focus points (I usually put the red dot on an eye). I am so confused because I can get a tack sharp image, change nothing at all and then the next image in line is not sharp at all.

Here is my equipment I typically use:
Canon EOS 40D
Canon EOS Rebel t2i
Canon 50mm 1.8
Canon EF 17-40mm f/4L USM
Canon Speedlite 430 EX II
Two 160 Watt Strobe Softbox
1 Flash MonoLight with umbrella

Any help would be greatly appreciated.

Settings: Obviously they very but I try to keep my ISO low 100 or 200 to prevent noise and then shutter at 1/125 or higher and then as low of an f-stop as possible with these settings but have tried increasing f-stop to see if this helps with getting more of my image in focus and sharp.

Both Pictures: 1/160 sec f 2.8 ISO200 The top image is not as sharp as the bottom image at 100%

you would need to provide examples with exif information to figure this out.

How do I upload photos here?

A gear list is useless in determining why your shots are "sharp" or "soft". Post up pictures with EXIF data and you can get much better answers.

attachments in the 'advanced posting' screen.

I don't see any difference in sharpness between the two posted images. Both are overexposed a bit, though - the first a little more than the second.

Because some are focused differently than others?

You probably moved slightly after attaining focus and before releasing the shutter.

Also both are horribly overexposed and not composed very well either.

Well at a 100% one image is very clear and the other is not. I did not edit these images, they are SOC. I just want to figure out why some are sharp and then the next is not.

with this being a 50mm, and this being cropped in, how far away are you from the subject?

if you were maybe say 5ft from the subject, only about 3 inches of your subject is in focus.

so the image that looks really sharp to you is because you have the focal plane lined up with her the subjects face.

on the first image, your focus seems to be on the pieve of costume closest to the camera, so everything a couple of inches behind that is out of focus. is there a reason you used 2.8 for your apature?

i don't shoot babies very often, but my experience has been that they don't tend to stay very still, so a narrow DoF almost never works out, unless they are asleep

hvaught32 wrote in post #15095171
Well at a 100% one image is very clear and the other is not. I did not edit these images, they are SOC. I just want to figure out why some are sharp and then the next is not.

How about showing us 100% crops of where you thought you were focusing.

An unrelated question: Why the camera tilt for the first shot? Quite honestly, I have never seen a single "tilted camera" shot that seemed to have good composition when it was obvious (because of something within the image) what was supposed to be horizontal or vertical in the real world. I've been asking folks who do it why they do it and have not gotten a solid answer yet.

I was about 5 feet away from my subject. Can you explain more on this factor?

I used a 2.8 apature because I was shooting a fast baby so my thoughts were that my shutter speed needs to be high. I generally try to keep my noise down so I try to keep my ISO as close to 100 as I can. Since my shutter is fast, my ISO and apature needs to be lower to allow more light in, right? Then I try to lower my aperture and bring my subject away from the background as far as I can to get more bokeh. Also I was reading that on the 50mm the sweet spot is one or two stops up from wide open.

I am learning here so let me know if I should be doing something different.

SkipD wrote in post #15095313
How about showing us 100% crops of where you thought you were focusing.

An unrelated question: Why the camera tilt for the first shot? Quite honestly, I have never seen a single "tilted camera" shot that seemed to have good composition when it was obvious (because of something within the image) what was supposed to be horizontal or vertical in the real world. I've been asking folks who do it why they do it and have not gotten a solid answer yet.

I took several images and just picked two images that where taken practically back to back to show that with no change in my settings, one image is clear and the other is not. Not for any other reason than that. This image angle is not a preference for my personal photos, however I find that many clients do like the "odd" angle because it is different than your typical everyday competition. I try to offer a lot of variety and I find that is one way I can. I am no pro here and am still learning but maybe it's just a personal preference. All I know is that I have noticed that many clients do choose those "odd" angles over the traditional composition.

hvaught32 wrote in post #15095384
I was about 5 feet away from my subject. Can you explain more on this factor?

I used a 2.8 apature because I was shooting a fast baby so my thoughts were that my shutter speed needs to be high. I generally try to keep my noise down so I try to keep my ISO as close to 100 as I can. Since my shutter is fast, my ISO and apature needs to be lower to allow more light in, right? Then I try to lower my aperture and bring my subject away from the background as far as I can to get more bokeh. Also I was reading that on the 50mm the sweet spot is one or two stops up from wide open.

I am learning here so let me know if I should be doing something different.

What kind of lighting were you using for the shots?

Have a look HERE for a very handy depth of field calculator, it may help you select the right aperture setting for what you are shooting.

Also for those of you that state that these images are overexposed, can you tell me why? My whites are not blown out at all and they don't appear overexposed on my computer. Could it calibration?MAC vs PC or even personal preference? When I print through my lab everything looks great.