Soft/Out Of Focus when cropping?

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Dredd123

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Hi,

Is it to be expected that cropped shots (say 100% crop) will look significantly softer/out of focus than the original shot? If not, I think I have a problem somewhere because that's what I'm getting and I think I will need some help troubleshooting please!!

Thanks in advance,
Dave.
 
Cropping in shouldn't reduce IQ, though it depends on the IQ of the original image. Dont forget that viewing a big picture at a small size on a screen will more than likely make it look better than it is simply because flaws are reduced to a minimum. Best thing would be to post some examples of the original shot and the cropped versions you are worrying about so we can get a better idea of where the problem, if any, lies. If you can, also post the exif data/camera settings and what equipment you used.
 
and what you did to it on the PC too.

You never know, it might just not be sharpened enough (I did that!)
 
You mean the picture looks ok when you look at it so it all fits on the screen, but when you zoom in it looks soft and blurry?

If so, then that is just degrees of softness.

Some people who are perfectionists will insist on only using shots that are sharp at 100%, others will be happy if it looks ok at 800 pixels on the longest edge posted on this forum ;-)
 
I'll post a few examples when I get home tonight.

Is there anywhere (free) that I can upload the images to then link to? (they are about 8MB when converted from RAW to JPG at full quality.

Thanks,
Dave.
 
Photobucket.
 
Here's an example photo along with crop. You will need to download the photos from Picasa to see them at their full size. Both the original and the crop were sharpened to 10 using Digital Photo Professional on the RAW tab. Photo was taken using a 1D MKII and Sigma 120-300 f/2.8 EX DG APO on a tripod.

http://picasaweb.google.com/lh/photo/ECaegguSAcn5EwarH3UNLg?feat=directlink

http://picasaweb.google.com/lh/photo/gQYqQANVTwigvdnttQN7Vg?feat=directlink

EXIF Data:

File name
NO0U0001.CR2
Camera Model Name
Canon EOS-1D Mark II
Firmware
Firmware Version 1.2.3
Shooting Date/Time
28/07/2009 18:46:24
Tv(Shutter Speed)
0.5Sec.
Av(Aperture Value)
F8.0
Metering Modes
Evaluative metering
Exposure Compensation
0
ISO Speed
100
Lens
120-300mm
Focal Length
300.0 mm
Image size
3504 x 2336
Image Quality
RAW
Flash
Off
White Balance
Auto
AF mode
One-Shot AF
Picture Style
-
Parameters
Tone Curve : Standard
Sharpness level : -
Pattern Sharpness : -
Contrast : 0
Sharpness : 0
Color saturation : 0
Color tone : 0
Long exposure noise reduction : -
High ISO speed noise reduction : -
Highlight tone priority : -
Color matrix
1
Color Space
sRGB
File Size
8835 KB
Dust Delete Data
No
Drive Mode
Single-frame shooting
GPS Data
Satellite signal status : -
Date(UTC) : -
Latitude : -
Longitude : -
Altitude : -
Geographic coordinate system : -
Owner's Name
-
Camera Body No.
250980
 
Your test photo seems to be shot at f=300mm with a shutter speed of 1/2 a second. That's asking an awful lot from your tripod. If you're looking for sharpness then I'd suggest shooting outdoors in decent light so that any possible hint of shake can be removed from the equation.

Plus, having a nice contrasty target will help. In this case it does look like the AF has locked onto the net curtain rather than the soft toy.

Finally, there's something odd about your image sizes. Your EXIF data says the original shot was 3504 x 2336 pixels, but the "full size" version on Picasa is only 1600 x 1067. Either it's been reduced, or it's a crop, or both - either way it's not the full image.
 
Agree that you need to do a better test. :)

It does look like the focus has picked up on the net. Set the autofocus point to centre so you nail the focus on your test object and give it another go with some more light on your subject.
 
Yup, I can't see how the dog thing would be the subject of the auto-focus being that position in the frame and as the others say, the net curtains do look quite sharp.

How many focus points did you have active? All or just the centre one?

Looks about right to me...

Try some decent light, centre focus point placed on a contrasty target and shutter speeds as high as you can get them at something below ISO 400 and at around f8 to get that lens as sharp as possible....
 
Thanks for all the comments. I had only the centre focus point active and it was placed on the dogs head, therefore I don't understand why it would have focused on the net curtains? (could this be what I've heard of as back focusing?)

Don't know why Picasa would have changed the image size. I did try Photobucket first as suggested but the main file is too big for Photobucket and gets reduced. Any other suggestions as to where to host the files without them being modified?

I have similar photos taken with the 1D MKII and 70-200 f.28 IS, plus a 40D with the Sigma and also with the 70-200 for comparison purposes. All the crops look soft to me; I would like to post them also for you to check and see what you think.

I will also repeat the tests in better light outside.

Thanks for all the help guys.

Cheers,
Dave.
 
Pretty sure that in your test pic the AF has picked up on the curtains. The focus point is quite a lot larger than the square in the viewfinder and given that the curtain has good contrast to lock on to compared to the dog (which is a poor test target, especially set against a bright window) it has been drawn to that.

The image also looks softer because it is low contrast. Contrast is often considered to be a more important component of sharpness than resolution.

As others have said, you need to shoot an outdoor image, in good light, at a greater distance to minimise potential focusing errors. But even the crispest image will degrade very markedly when viewed at 100%.
 
OK, done a couple of test shots outside. I have persisted with the dog ornament as the target. I used a tripod and also used mirror lockup and cable release. The first two photos are the original and crop using auto focus with just the centre focus point over the dog's nose. The last two photos are using manual focus. Thanks for looking.

http://picasaweb.google.com/lh/photo/b1weJGHVOHNqONl4XibQKw?feat=directlink

http://picasaweb.google.com/lh/photo/MabB3BpHsAy1jYS2JMYr5A?feat=directlink

http://picasaweb.google.com/lh/photo/89nNZlDNN-6WOBQsn99rFg?feat=directlink

http://picasaweb.google.com/lh/photo/9kbZ7Zgh0cOWrXNcqJCIgA?feat=directlink
 
They are all sharpened to 10 in DPP on the RAW tab.

Well, if these are OK my "problem" lies elsewhere. Either I am just crap at panning motorsports, or I need to get closer to the action/get a longer lens.

Dave.
 
Dredd123 said:
They are all sharpened to 10 in DPP on the RAW tab.

Well, if these are OK my "problem" lies elsewhere. Either I am just crap at panning motorsports, or I need to get closer to the action/get a longer lens.

Dave.
Click to expand...

Sounds like you have found the answer here :thumbs: Your objective should always be to fill the frame as tighly as possible with your subject. The moment that you start cropping to get the framing you want, you are throwing away large lumps of quality.
 
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