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04-26-2011, 07:37 AM   #1
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K20D, unsharp photos!

Bought a used K20D a few months back, came with the kit lens (DA 18-55mm AL WR).
I'm not especially impressed with the sharpness of my photos! I know I have a lot to learn, but I'm not new to photography in general, so hope for some advice.
Do I have an issue with the AF, or is this what I can expect from a kit lens.

URL="https://www.pentaxforums.com/forums/attachment.php?attachmentid=89787&stc=1&d=1303828431"]https://www.pentaxforums.com/forums/attachment.php?attachmentid=89787&stc=1&d=1303828431[/URL]

Iso 100, f11, 1/60. Handheld. Sharpened in Aperture.


Last edited by BakDinitzen; 12-30-2012 at 04:35 AM.
04-26-2011, 07:52 AM   #2
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In My experience, the Kit lens (18-55) isn't the sharpest knife in the drawer. It is a it will get you there lens. Further, in my experience, the kit lens performs best around its mid focal lengths. In a short zoom it's probably the best bang for the buck but I wouldn't get my expectations real high with it.

04-26-2011, 09:59 AM - 1 Like   #3
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Problems with sharpness can be divided into four areas.

Blame the subject - A fast-moving kid, a windblown flower, waves, earthquake, etc. The solution is often a high shutter speed or flash.

Blame the photographer - camera movement, didn't wait for SR, used a shutter speed that's too slow, used SR on a tripod, many other potential errors. Practice and awareness help.

Blame the camera - Autofocus, diopter setting, mirror slap, possibly something broken or out of adjustment. Once repair issues are eliminated, the photographer usually has to do things that the camera can't.

Blame the lens - Decentering, soft corners, possibly something broken or out of adjustment.

The photo you have isn't very good at identifying or eliminating any particular cause. You should take photos designed to test some of the potential causes I've listed above. Start with easy-to-eliminate issues by securing the camera to a solid tripod, turning off SR, using a stationary subject, maybe even 2 sec. delay and a remote.

Then you have to be creative. To test AF, you must know where the camera chose to focus before you can tell whether it failed. Your example photo has a lot of depth of field and hundreds of potential targets. Maybe you only intended one tree to be in focus but the camera isn't that smart. Instead, you need one high-contrast target, bigger than the red AF point dot in the viewfinder. You should use the widest possible aperture on the lens, to make the area in focus more obvious. Having the target at an angle to the camera helps too.

For lens manufacturing problems, a classic brick wall is nice. Have the camera at a reasonable working distance away, sensor parallel to the wall, focus manually, and see if one side is sharp while the other isn't. Many lenses have a curved focal plane so a few meters away from the wall will insure that your results are not just showing the curved focal plane.

Testing yourself is harder because there are so many mistakes you can make. You can look at the EXIF for soft photos and see if SR was working properly. See how close the shutter speed is to the typical guideline of 1/focal length. This guideline varies. Some say it should be 1/(focal length X 1.5) to account for the APS-C sensor. The biggest variable is not the sensor size, it's you. Everyone should know how steady they can hold the camera, and where camera shake is likely to be a factor. I read once about someone attaching a laser pointer to the hotshoe and taking photos in a dark room to evaluate this.
04-26-2011, 10:39 AM   #4
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Hard to tell without seeing the full original image, but it should be sharper than that.




This is how mine behaves on a K-7 over a range of stops and focal lengths - Collection: SMC Pentax DA 18-55mm f3.5-5.6 AL WR

04-26-2011, 10:44 AM   #5
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As Just1MoreDave mentioned, the brick wall test is a good test to use.

I test all of my lenses and bodies using the "Tennis Net Test", which is one of the best ways (if not the best) to test for a number of different things.

Using the "Tennis Net Test", you can test Lens Sharpness, AF Focus Point Accuracy, MF Focusing Accuracy, Lens DOF Performance, Contrast, and ISO Performance just to name a few, all within the same shot.

Attached is an example test image, shot with the K5 when I first got it in. Did this test to test the accuracy of the "Green" focus indicator on the K5 and also to test IQ.

About the Tennis Net Test: Shot at approx a 45 degree angle, focused 3rd knot down and 3rd knot from RTL, shot at night with the court lights on. Net is great to shoot this way as there is very fine detail in the net braiding.

(If anyone knows a better test than this, please post)
Attached Images
 
04-26-2011, 11:38 AM   #6
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Thanks for the replies. I se I have quite some work ahead of me, before I can determine the problem. And there clearly is a problem - I have not been able to produce as crisp and sharp photos as the ones you have attached - thank you for that.
I think I will start with the brick wall (I'm not a tennis player), and off course the personnel skills.
04-26-2011, 12:41 PM   #7
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From the EXIF it seems that you are struggling both with sharpness and with contrast - you don't have a cheap 'lens protector' filter on the front of the lens by any chance ?
04-26-2011, 01:14 PM   #8
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no, don't have any filters!

04-26-2011, 04:03 PM   #9
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QuoteOriginally posted by BakDinitzen Quote
no, don't have any filters!
It's a process of elimination then :

Is your technique OK - half press the shutter button, wait for focus confirmation to come on, wait for shake reduction indicator to come on, then press the shutter button all the way, slowly and gently ?

Is anything ever in focus and sharp - take a shot of a page of newspaper print at an angle in good natural light, focusing somewhere in the middle, at least some of the print somewhere should be in focus and sharp ?

If you are shooting jpeg is there some setting (I don't have a K20D) that you have inadvertently tweaked - reset the camera to defaults if need be ?

etc...
04-26-2011, 05:22 PM   #10
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QuoteOriginally posted by kh1234567890 Quote
It's a process of elimination then :

Is your technique OK - half press the shutter button, wait for focus confirmation to come on, wait for shake reduction indicator to come on, then press the shutter button all the way, slowly and gently ?

Is anything ever in focus and sharp - take a shot of a page of newspaper print at an angle in good natural light, focusing somewhere in the middle, at least some of the print somewhere should be in focus and sharp ?

If you are shooting jpeg is there some setting (I don't have a K20D) that you have inadvertently tweaked - reset the camera to defaults if need be ?

etc...
I agree!!! I use this test for every lens I own. It's a great way to see what exactly you are pointing the camera at, pick out an area or even a word and take a pic, check it out. If it's not in focus take another and take your time. If you can never get any of the print in focus, the problem is the lens or AF in the camera.

QuoteOriginally posted by BakDinitzen Quote
Bought a used K20D a few months back, came with the kit lens (DA 18-55mm AL WR).
I'm not especially impressed with the sharpness of my photos! I know I have a lot to learn, but I'm not new to photography in general, so hope for some advice.
Do I have an issue with the AF, or is this what I can expect from a kit lens.

URL="https://www.pentaxforums.com/forums/attachment.php?attachmentid=89787&stc=1&d=1303828431"]https://www.pentaxforums.com/forums/attachment.php?attachmentid=89787&stc=1&d=1303828431[/URL]

Iso 100, f11, 1/60. Handheld. Sharpened in Aperture.
I think the Kit Lens is a good lens for all around Auto Focus photography, it's the one I take to events where I will usually need the wide end and in close quarters. It tends to get a bashing here and there, sometimes rarely used after one acquires more lenses but of all my AF lenses this is the one I would want to have if I could only have one.

Below is a photo using the Kit Lens at f5.6 and at 55mm, I think it's pretty sharp, maybe a touch too much unsharp mask applied, but at least I know the lens is capable of producing good images in the right light.

Proper exposure will lead to better contrast which leads to sharper looking images. I would try a different subject since your landscape lacks a little contrast and color, which is really what you're looking for. Also, you have to watch what settings you are using in your AF mode, try switching to spot focusing. IMHO, f8 works better than f11 and I've never gone above f8 on any lens I use. If you have a friend with a Pentax, maybe you can try out their lens, or go to a camera store that carries K-mount lenses and try them out right there, check them later.

Just keep trying, somewhere on that lens/K20D will be a magical setting the will produce great images; it's finding those settings that is the most fun part of photography...


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04-26-2011, 06:30 PM   #11
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Nice shot of the Old Bay, see that you are from Baltimore, Old Bay and Maryland (the beer too) mean only one thing, the best Crab Eating on the planet
04-26-2011, 11:23 PM   #12
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Thanks to all off you for your help so far - very useful. I have found a calibration sheet which I will try out one of the comings days and post here, maybe tomorrow. Would love some feedback.
The best to all,
John
04-26-2011, 11:40 PM   #13
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You'll want to have very good camera holding technique to get truely sharp pictures at 1/60. Are you for instance holding the camera with your left hand cuped under the lens? It's amazing how many people I see holding a DSLR with their left palm on top of the lens and their elbows sticking out like chicken wings.
04-27-2011, 12:30 AM   #14
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So many possibilities. Lens, camera, settings, technique etc.

One fun thing to do with lenses to help get familiar with them is to run them through their paces. And by this, I mean grab a tripod and start taking images throughout the zoom and aperture range. This way, you can assess the output of your image(via EXIF) and get better acquainted with the equipment.

And though it might seem tedious, it may actually be the most helpful thing you ever did
So grab you favorite tripod, remote, set your camera for mirror-up, turn off SR, and start taking photo's. (I like to make sure I'm on solid ground too to help clear any/and all interferences possibilities). LV can help too.

FTR. the 18-55 is capable of very sharp images(as seen here with this throwaway shot);



Hope this helps
04-27-2011, 12:50 AM   #15
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QuoteOriginally posted by twitch Quote
You'll want to have very good camera holding technique to get truely sharp pictures at 1/60.
I was going to suggest the same thing. Sometimes it's tempting to just fire away, forgetting basic technique and confident that SR will fix everything. Try f/8 at 150th or 200 (stick it on Tav) and see if that improves things. Are you shooting in RAW or JPEG? If JPEG, how do you have sharpening set up in camera? I see you sharpened the photo in Aperture. How much did you give it?
As others have demonstrated, you can get decently sharp shots from the kit lens. I don't think you're too far off and you've got plenty of good suggestions to try. I understand how depressing it is to get hold of a semi-pro camera, thinking it's going to produce stunning shots for you and it's a real let-down when it doesn't. The good news is it's only technique. You'll get there.

Last edited by Wombat; 04-27-2011 at 12:57 AM.
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