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09-02-2012, 12:08 PM   #1
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Sharpness

Hi,
Just wondering whats being done wrong here... is at a focusing issue, or does it need a faster shutter speed, or something else?

100% crop
Name:  crop.jpg
Views: 814
Size:  124.9 KB

and full image

Name:  res.jpg
Views: 793
Size:  425.0 KB

thanks
Steve

09-02-2012, 12:16 PM   #2
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Poor lens or PPS. What did you use?
09-02-2012, 12:17 PM   #3
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Do you have any more information? Lens? Focal length, aperture, shutter speed, etc?
09-02-2012, 12:18 PM   #4
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The horizontal and vertical lines appear to be equally affected. That suggests focus to me. But at 100% crop you are leavng no forgiveness of any error, such as your capacity to focus (MF) or the AF system if using it. In my view, composition should result in the intended image approximately (or even exactly) filling the frame, in which case your probem goes away.

09-02-2012, 12:19 PM   #5
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I was hoping it would show the exif info.. erm how do you get an image to show it here?
sorry
Steve
09-02-2012, 12:28 PM   #6
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Not sure about that, so I checked with an online exif viewer:

smc PENTAX-DA 18-55mm F3.5-5.6 AL WR
Shot at 18 mm
Manual exposure, Not Defined, 1/30 sec, f/22, ISO 80, Compensation: -1/2
Subject Distance Range: Distant

So here we go:

Subject distance range - the focus is based on distant and at F22, everything SHOULD be in focus.

However, shooting at F22 on an APS-C sensor is going to introduce a lot of diffraction, and that can make the image soft. With the 18-55, I believe the sharpest apertures are F8-F11. Shooting beyond F13 will start to make things quite soft, especially if you are pixel peeping.

The 18-55 kit lens is a pretty good lens, but it's not going to be outstanding if you are used to better lenses.

http://farm7.staticflickr.com/6203/6060681385_d7154e6477_o.jpg
^full size image - shot at F11. Definitely better than yours at F22.
09-02-2012, 01:07 PM   #7
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QuoteOriginally posted by JinDesu Quote
Not sure about that, so I checked with an online exif viewer:

smc PENTAX-DA 18-55mm F3.5-5.6 AL WR
Shot at 18 mm
Manual exposure, Not Defined, 1/30 sec, f/22, ISO 80, Compensation: -1/2
Subject Distance Range: Distant

So here we go:

Subject distance range - the focus is based on distant and at F22, everything SHOULD be in focus.

However, shooting at F22 on an APS-C sensor is going to introduce a lot of diffraction, and that can make the image soft. With the 18-55, I believe the sharpest apertures are F8-F11. Shooting beyond F13 will start to make things quite soft, especially if you are pixel peeping.

The 18-55 kit lens is a pretty good lens, but it's not going to be outstanding if you are used to better lenses.

http://farm7.staticflickr.com/6203/6060681385_d7154e6477_o.jpg
^full size image - shot at F11. Definitely better than yours at F22.
All that seems spot on to me. I would only add that 1/30th is a bit slow for many folks to handhold.
09-02-2012, 02:25 PM   #8
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QuoteOriginally posted by JinDesu Quote
1/30 sec, f/22, ISO 80,
Yeah I think 1/30 is too slow, ISO is lower than it needs to be and aperture is smaller than it should be. I guess I'd have gone TAv at 1/160 & f11and camera-determined ISO. Still, with some pp, it could be decent--if not magazine quality.

09-02-2012, 02:47 PM   #9
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1/30 is not so slow considering it's at 18mm
09-02-2012, 03:27 PM   #10
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QuoteOriginally posted by Anvh Quote
1/30 is not so slow considering it's at 18mm
It most likely is bordering on slow, specially if trying to freeze that plane also.
09-02-2012, 03:47 PM   #11
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1/120th at f11 would have been sharper...

I find 1/30th boardering slow to handhold...
09-02-2012, 06:07 PM   #12
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Here's my rule of thumb on problems like this. Assuming the lens is decent, then look for SOMETHING in the image that is sharp (let's take the crop image of Big Ben up closer). If there is something sharp in the image, then you have a problem with what you focused on. If nothing is sharp, then it is probably motion blur. At 1/30 of a second, motion blur can easily occur, even with an 18mm FL and vibration reduction. How were you shooting this, handheld? Was what you were standing on moving (you seem to have taken this from the middle of the water, maybe a bridge, but a boat is also possible)? Do you practice good habits when pressing the shutter button (only moving the finger and not the entire arm or body), do you press it gently or hammer it down? Did you have like 10 cups of coffee that day?

It is hard to say for certain why this is happening, but with that lens you should be able to do much better than what you had. I think it was a bit of motion blur. Watch the coffee and tea!

Regards,
09-02-2012, 11:24 PM   #13
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Thanks for all the comments, very informative. so in future, keep it below f11 and keep the shutter speed up.

btw it was hand held on a bridge (southern half of Hungerford bridge to be precise)

apart from when its too bright are there any other times that it is useful to go above f11 ?

thanks again
Steve
09-03-2012, 12:32 AM   #14
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1/30 is not slow to hand hold with SR.
09-03-2012, 01:05 AM   #15
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QuoteOriginally posted by JinDesu Quote
However, shooting at F22 on an APS-C sensor is going to introduce a lot of diffraction, and that can make the image soft. With the 18-55, I believe the sharpest apertures are F8-F11. Shooting beyond F13 will start to make things quite soft, especially if you are pixel peeping.

The 18-55 kit lens is a pretty good lens, but it's not going to be outstanding if you are used to better lenses.

http://farm7.staticflickr.com/6203/6060681385_d7154e6477_o.jpg
^full size image - shot at F11. Definitely better than yours at F22.
Both the OP and yours would look a lot better if you were to correct the CA which is quite noticeable with this lens at 18mm (it disappears completely at some 37mm).
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