Loss of sharpness?

[Davi]

I've been noticing recently that quite a few of my photo's are coming out a fairly long way short of satisfactory on the sharpness - I presumed it was just me miss-aiming focus with my somewhat limited 3 point AF, but after the weekend I'm not so sure - I kept firing off bursts of shots only altering the focal length, keeping the same AF point, keeping it well and truly steady, but suffering extremely variable results. The only thing I know to question is the lens - excuse my lack of technical terminology, but the most forward part, that goes in and out on zoom that has the hood attached to, wobbles very slightly, it's not tight - is this normal? I'm pretty sure it's been like it since new so didn't think anything of it.

It's a Nikor so not a cheapy

[RobDickinson]

It unlikely your lens is parfocal (i.e. stays focused as it zooms).

You will probably have to refocus it once zoomed.

[Davi]

Sorry Rob, I explained badly - what I mean is I kept the same focal point and subject matter - i.e. everything as constant as I could, just varied focal length. It was refocussed each time. I also tried to ensure that the focal point was a nice contrast ridden area to give it an easy life. I started wondering because I took some pics at a friends wedding, and the consistency in sharpness and overall quality of shot was so shockingly variable. I know I'm still a very low learner, but I couldn't work out how I was doing so badly one minute and so well the next.

Edited by Davi on Monday 2nd August 11:07

[...Mole...]

What lens are you using, and what Aperture are you usually using when taking these photos that appear soft?

[Gemm]

It depends on whether the softness comes from inaccurate focusing or camera shake. If you zoom in, there's often less light, so the shutter speed would be slower, and together with longer focal length, camera shake is far more likely to occur. Do you think this is the case?

Edited by Gemm on Monday 2nd August 11:29

[Davi]

it's a Nikkor 18-70, this one in fact:

http://www.kenrockwell.com/nikon/1870.htm

I'd not say there is any particular aperture that it looks soft on, and that is what is confounding me - I can't reliably reproduce the soft (or sharp!) images, it seems completely random.

At the weekend there was excellent lighting and I don't think that camera shake would have been an issue.

[Colin RedGriff]

Can you post some examples with the EXIF data?

[LongQ]

Has it slipped into a Preset mode unnoticed?

[Davi]

not got much here - but a couple from the wedding which give a fair example of what I mean - both taken at roughly the same distance, same direction to sun etc etc etc.... SOTC, just 100% crop.

Sharp:



EXIF:
<exif:ExposureTime>1/200
<exif:ShutterSpeedValue>7643856/1000000
<exif:FNumber>63/10
<exif:ApertureValue>5310704/1000000
<exif:ExposureProgram>3
<exif:DateTimeOriginal>2010-07-30T15:07:23.70+01:00
<exif:DateTimeDigitized>2010-07-30T15:07:23.70+01:00
<exif:ExposureBiasValue>0/6
<exif:MaxApertureValue>43/10
<exif:SubjectDistance>237/100
<exif:MeteringMode>2
<exif:LightSource>0
<exif:FocalLength>700/10
<exif:SensingMethod>2
<exif:FileSource>3
<exif:SceneType>1
<exif:FocalLengthIn35mmFilm>105
<exif:CustomRendered>0
<exif:ExposureMode>0
<exif:WhiteBalance>0
<exif:SceneCaptureType>0
<exif:GainControl>0
<exif:Contrast>0
<exif:Saturation>0
<exif:Sharpness>0
<exif:SubjectDistanceRange>0
<exif:DigitalZoomRatio>1/1
<exif:ISOSpeedRatings>200
<exif:Flash rdfarseType="Resource">
<exif:Fired>True
<exif:Return>3
<exif:Mode>3
<exif:Function>False
<exif:RedEyeMode>False

Soft:



EXIF:

<exif:ExposureTime>1/200
<exif:ShutterSpeedValue>7643856/1000000
<exif:FNumber>63/10
<exif:ApertureValue>5310704/1000000
<exif:ExposureProgram>3
<exif:DateTimeOriginal>2010-07-30T14:24:21.70+01:00
<exif:DateTimeDigitized>2010-07-30T14:24:21.70+01:00
<exif:ExposureBiasValue>4/6
<exif:MaxApertureValue>43/10
<exif:SubjectDistance>398/100
<exif:MeteringMode>2
<exif:LightSource>0
<exif:FocalLength>700/10
<exif:SensingMethod>2
<exif:FileSource>3
<exif:SceneType>1
<exif:FocalLengthIn35mmFilm>105
<exif:CustomRendered>0
<exif:ExposureMode>0
<exif:WhiteBalance>0
<exif:SceneCaptureType>0
<exif:GainControl>0
<exif:Contrast>0
<exif:Saturation>0
<exif:Sharpness>0
<exif:SubjectDistanceRange>0
<exif:DigitalZoomRatio>1/1
<exif:ISOSpeedRatings>200
<exif:Flash rdfarseType="Resource">
<exif:Fired>True
<exif:Return>3
<exif:Mode>3
<exif:Function>False
<exif:RedEyeMode>False

Excuse messy Exif, just exported it earlier so copy pasted!

[Gemm]

I don't think looking at 100% crop helps here. We need to look at more overall image to see if it's a focusing issue, etc.

[Davi]

I'll have to grab something later - that's all I have here at the mo.

[LongQ]

The samples, with a default touch of sharpening applied, look about as sharp as the subjects might want to see as far as skin texture and tones are concerned. IMHO.

Much time is spent softening skin tones in portraits ....

But then that doesn't tell us much about the overall images as already mentioned.

[Simpo Two]

The front of the 18-70 does wobble but from my experience I don't think it affects the image significantly.

What you're probably experiencing is a combination of 'AF is not perfect' plus '100% crop fetish'. Remember that in the real world photos are not viewed at this magnification, and when printed out at 6x4 etc they will look fine. If you zoom into pixels looking for problems then you'll probably find them

NB: AF performance is mostly a function of the body.

We all struggle for perfection, but eventually realise that 99% is pretty good.

Edited by Simpo Two on Monday 2nd August 22:42

[Gemm]

Simpo Two said:

'100% crop fetish'

[...Mole...]

Simpo Two said:

'100% crop fetish'

I have a friend that bought a Nikon 24-70mm f/2.8 to satisfy his 100% crop fetish, and he still manages to find problems with it!

[Simpo Two]

As in 'I spent all that money and if you zoom in real close you can see loads of little squares appearing...'?

Yes chum, they're called atoms.

I quite like the idea of pixels being photographic atoms. 'Phatoms'?

[Davi]

LOL well the 100% crop was in this instance only to show the difference in sharpness without posting pics of friends who may not want their pics put up. Whilst okay at a 6 x 4 print, if you wanted a "reasonable" blow up done, it looks a bit crap. Looked last night but as suspected anything less than sharp I've already binned, so will have to set up a test shoot to recreate it. It's just the lack of consistency that is irking me!

Trying to bypass the problem by saving for new kit (whether needed or not ) but that's another thread altogether...

[Elderly]

Do you have your camera set to FOCUS PRIORITY or RELEASE PRIORITY?

The former will not let you take a picture until the camera is locked on to something, but
the latter will allow you to operate the shutter whether the camera has finished focusing or NOT.

You say that your problem is not at a specific aperture but it's more likely to be at a specific focal length(s)
of your zoom.

I don't know what Nikon camera body you have (3 autofocus points?) but Nikon autofocus modules are improving all the time;
for instance the 'Multi-cam 3500' of the D300 is said to be a big improvement over the 'Multi-cam 1000' of the D200.

[Davi]

focus priority as far as I know (a reasonable guess as it won't let me fire if it cant focus!)

It's just a lowly D60 at the moment, to be upgraded to a D *insert a 3 or 7 here depending on how much my tools sell for on ebay*00