Lens Sharpness - How to test

[Marko]

cool that's what I wanted to know.

Ok then - other possibilities
- is it possible the insect moved a tad during the exposure?
- for macro type subjects depth of field is reduced of course but the part you focused on should of course be tack sharp. I'm not convinced at all that it's even possible for f-9 to cover both wings on yr 55mm.

On older lenses it's easier to see what distance a given F-stop will cover as the info is often right there on the barrel. You'll want to check the specs of yr lens for this info as well as the minimum focusing distance.

If I had to bet on this though, I'd bet on camera shake.
Hope that helps

any other opinions on this?

[F8&Bthere]

Sharpness is a tricky bugger. When I've been unhappy with sharpness in my photos in the past, if I was able to eliminate subject movement, camera shake, and DOF issues first, I'd often end up realizing, or being told, I'm expecting too much (ie. pixel peeping). And it was often when I was trying to assess my copy of a recently bought lens. And other times I have found that lighting/ISO made all the difference of a slightly soft shot to a nice crisp one.

I assume you used a tripod. And if that's the case and if we give the lens the benefit of the doubt here, I'd have to agree with Marko's hunches. But as for the lens quality or possible front/back focus issues, of course it's hard to tell from the size posted here.

Does it look to you in viewing and zooming in the full size photo that the surface of the log is sharper than the insect? The answer to that question may say a lot. The shot looks good to me but I kinda see what you mean about the insect could be crisper- but to me it looks close enough that a little post processing could make an improvement.

Edit- oh and to answer the question- how to properly test- I'm betting by the time you read this post you've already googled it and found a pile of resources, like resolution charts you can print off and place flat on a wall, or the ones for front/back focusing (45 deg angle) etc

[Iguanasan]

Thanks for the feedback. No, I hadn't Googled yet as I was at work but I will shortly thanks for the keywords. Here is the original (in Flickr and PicasaWeb) for discussion. Maybe it is camera shake since I was not using a tripod, however, it is 1/80s and I believe I'm fairly steady - not as steady as a tripod obviously. Also, this has the lens stablization built in, this is the Rebel XSi and finally, the fence rail looks fairly sharp to me but maybe that's just my bad vision

Photos below the EXIF

Full EXIF Info
==========
Make - Canon
Model - Canon EOS DIGITAL REBEL XSi
Orientation -
XResolution - 72
ResolutionUnit - Inch
YResolution - 72
Software - Picasa 3.0
DateTime - 2009:06:27 15:31:16
YCbCrPositioning - Co-Sited
ExifOffset - 216
ExposureTime - 1/80 seconds
FNumber - 9
ExposureProgram - Manual control
ISOSpeedRatings - 100
ExifVersion - 0221
DateTimeOriginal - 2009:06:27 15:31:16
DateTimeDigitized - 2009:06:27 15:31:16
ComponentsConfiguration - YCbCr
ShutterSpeedValue - 1/83 seconds
ApertureValue - F 9.11
ExposureBiasValue - 0
MeteringMode - Spot
Flash - Flash not fired, compulsory flash mode
FocalLength - 55 mm
UserComment -
SubsecTime - 03
SubsecTimeOriginal - 03
SubsecTimeDigitized - 03
FlashPixVersion - 0100
ColorSpace - Unknown (0xFFFFFFFF)
ExifImageWidth - 2880
ExifImageHeight - 2306
InteroperabilityOffset - 9588
FocalPlaneXResolution - 4865.60
FocalPlaneYResolution - 4876.71
FocalPlaneResolutionUnit - Inch
CustomRendered - Normal process
ExposureMode - Manual
White Balance - Auto
SceneCaptureType - Standard

Maker Note (Vendor): -
Macro mode - Normal
Self timer - Off
Quality - Fine
Flash mode - Not fired
Sequence mode - Single or Timer
Focus mode - MF
Image size - Large
Easy shooting mode - Manual
Digital zoom - None
Contrast - Normal
Saturation - Normal
Sharpness - Low , -32769
ISO Value - 32767
Metering mode - Center weighted averaging
Focus type - Auto
AF point selected -
Exposure mode - Manual
Focal length - 18 - 55 mm (1 mm)
Flash activity - Not fired
Flash details -
Focus mode 2 - 65535
White Balance - Auto
Sequence number - 0
Flash bias - 0 EV
Subject Distance - 0
Image Type - Canon EOS DIGITAL REBEL XSi
Firmware Version - Firmware Version 1.0.9
Sharpness (0D) - 52341
File number - 000 - 0000
Sharpness (A0) - 3


Flickr (Click to go to the site)


Picasa (Click to go to the site)