Ensure sharpness of images - Help please

[sutejok]

Hi,

 

I've been shooting a couple of events and kids, trying to build my portfolio. I

really want to become a child photographer. I think i can operate my equipments

pretty well that i hardly have problem (yet) over controlling them (except for

formatting my CF card before start shooting..... and the problem i'm going to

explain)

 

So, I am mostly happy with my results, except for when it comes to sharpness.

Most of the time I use my rebel xti body, 24-70 2.8 lens, 580ex flash. When

necessary or depending on situation, i'll use 70-200 f4. My camera body and

24-70 were recently calibrated by canon, so i'm not really doubting my gears.

Left to blame is my way of shooting, and my shutter speed/aperture combination

(or maybe something else i do not yet know). Mostly i try to use largest

aperture to get maximum bokeh, and i try shooting at minimum of 1/80sec,

assisted by flash, or natural light when outdoor. I try to take at least 3 shots

at a time. and oh, the flash is mostly sitting on the hot shoe, and it does beam

out the light to assist on focusing.

 

Questions for the pros (or anyone): how do you make sure that your results are

the sharpest you can physically get, especially when using largest aperture? Its

really hard for me to try to use manual focus, as kids move too fast for the

camera. or, are there tricks out there to do this on the computer?

 

Thx alot.

Tejo

[picturesque]

You first have to determine why the images aren't sharp. It could be a number of things. Subject motion, focal length, method of focus, equipment (just because Canon calibrated doesn't mean they are good), focusing ability of the gear, flash in combination... Perhaps post some examples and describe the situation(s).

 

If something is OOF in the camera, it can't be made to be in focus using the computer later. It can be made to look better/sharper, but not the same as if you started with an in-focus shot.

[sutejok]

Thank you for your response. here's one example:

http://www.sutejo-kurniawan.net/IMG_9035.jpg

 

I tried focusing on the face on this one, but all of the images (out of three) are a little soft on the face area.

[ilkka_nissila]

If you need to shoot at f/2.8 regularly and are concerned about sharpness, you probably should be using a fast prime instead. Few lenses are very sharp at the maximum aperture. E.g. 50/1.4 would be a good choice.

[rick rosen]

There are many factors that can affect sharpness. In order to determine whether your images are as sharp as they can be you need to start eliminating these factors.

 

Not all lenses are sharp wide open. In fact, most lenses lose sharpness at wide apertures. To test your lenses, set your camera's ISO at 400 and place it on a sturdy tripod outdoors in bright sun. Focus straight on at a brick wall or another textured surface. Use Av and shoot an image at every aperture starting from wide open. To really test, shoot that series at the widest zoom setting, an intermediate zoom setting and the longest zoom setting. By using a tripod you eliminate and camera movement. Evaluate those images at 100% magnification in the computer. That should tell you a lot about your lenses.

 

You should always apply a sharpening action to Canon image files in post production. Canon uses an anti-aliasing filter over their image sensor and that causes a slight loss in sharpness. As a general rule Canon's tech. people recommend applying a sharping using USM in Photoshop: amount -100, radius 0.3 pixels, threshold - 0

 

That'll start solving your issue with sharpness.

 

Rick

[fotografz]

The appearance of sharpness tends to be the function of 2 basic things ... edge

sharpness which can achieved by using the sharpening tools in Photoshop. The other

is overall contrast ... meaning NOT flat looking so there is an apparent dimensional

quality to the photo.

 

Your image isn't unsharp looking as much due to the equipment, but more so because

it's not lit well and not processed well.<div></div>

[neilambrose]

<p>The image you posted is in focus - at least one part of it, anyway. The plane of focus

was on the girl's top left button and is pretty sharp there. So either she moved as you

pressed the shutter, or your lens is slightly front focusing. Her face is behind the plane of

focus, hence soft. Her arms are before the plane of focus, hence also soft.</p>

 

<p>Irrespective of the fact that your lens has been calibrated, it's usually a good idea to

check it yourself by shooting a focusing chart (use google - you can download and print

your own) when the camera is mounted on a tripod. If it fails to focus exactly then you know

the lens is out of adjustment. If it does focus exactly, then you know it's your technique.</p>

 

<p>Also be aware that the kit 24-70 lens is rather soft anyway, and only holds maximum

resolution and contrast round f5.6 - f8.</p>

[fotografz]

A 24-70/2.8 is a kit lens?

[annealmasy]

Do you ever use the focus points in your camera to change your lens's selected focus? I think there's another term for this... ;) But anyway, once I got used to selecting my focus points, I do it ALL the time, and it's really helpful. Center-focus only works when you are framing your subject dead-center, or your aperture is small enough to keep even the edges in focus.

[sutejok]

Thank you everyone. I will definitely play around with the sharpen filter on photoshop. The example Marc posted seems to have pretty hard impact on the sharpness, something i do not know. I will definitely test on my lens sharpness too. Thx!!

[sutejok]

Btw, on Anne's note about the focus point; yes, i've been using that function on my camera.

 

Actually I have a question on this. What do you do if your desired focal point is not on either of the 9 dots that the camera will focus on? What i normally do is, when the desired point is between the center and top point, i will use the center point to focus (by placing the subject at the center), then i'll recompose the image after the camera/lens have measured the focus, while holding the shutter release button halfway pressed. Is this a bad practice?

[annealmasy]

Sutejo, the only problem with the focus/recompose method is that when you recompose you are most likely tilting your lens slighting from it's original plane. If you're shooting at a shallow depth of field, this could make all the difference between a sharp image and an out-of-focus shot. This problem is even worse with wide-angle lenses, with which you tend to be much closer to the subject.

 

It's rare that one of the available focus points isn't at least CLOSE to your intended focus subject. E.g., if you have to focus/recompose only a tad bit from an existing outer focus point, that will still be better than focus/recomposing from center to the outer edge of the frame.

[picturesque]

It looks like maybe a combination of several things--subject motion plus flash ghosting plus the focus point might have been off (back focus on the left button). For the flash ghosting, less flash would reach her face because she is carrying the bucket.

[surfidaho]

Howdy!

 

If you are shooting wide open, your depth of field is probably very shallow. There are many online calculators that tell you what your depth of field is for a given aperture and focal length. Here's one:

 

http://www.dofmaster.com/dofjs.html

 

If depth of field is shallow, and you focus, lock, and recompose, the type of error that Anne describes becomes very common. Even though the center sensor (cross type, f2.8) is more accurate than the outside sensors (single dimension, f5.6) the outside sensors are usually plenty good unless you are trying to use AI Servo, or are focusing in dim light.

 

I would suggest three things:

 

1. Use a tripod, monopod, or image stabilized lens whenever possible.

 

2. Use custom function 4 to move your focus button to the rear of the camera.

 

3. Always use One-Shot for stationary subjects, AI Servo with center point for moving subjects.

 

4. When photographing people with One-Shot, focus on the eye using the most convenient sensor point.

 

Later,

 

Paulsky

[johnmottershaw]

One other thing - I recommend getting somebody else to hold up the light diffuser

instead of asking the subject to do it!