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02-07-2010, 10:19 PM   #1
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K10D - I can't get sharp pictures. Please help!

Hello all

This is my first post here and I hope someone can help me. I've had my K10D for a while but due to illness have only more recently started getting to know it. I can't seem to get sharp pictures.

I printed a focus test chart I found online to see if my camera possibly had front/back focus issues but from my results I don't think either of those are the problem.

I would appreciate any productive suggestions/advice.

Regards

Byrnsy

The pictures below were all taken with the same set-up:
a. Subject on a flat table placed against at a ceiling-to-floor window on a bright, fully overcast day.
b. Camera on tripod at a 45 degree angle to subject and approx. 25cm from subject.
c. Shake Reduction turned off.
d. 2 second Self - Timer set.
e. SEL focus set at centre.
f. Autofocus system set to AF-S.
g. smc Pentax-DA 1:3.5-5.6 18-55mm AL kit lens.
h. Dial Mode Av set to widest possible aperture.
i. JPEG 10m, Image Quality 3 stars, Saturation 0, Sharpness +2, Contrast +1
j. ISO 100, 55mm, f/5.6, 1/125sec

First two pictures are of the printed focus test chart I used. Second two pictures are of a jewellery piece placed in the same position.

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02-07-2010, 11:00 PM   #2
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It looks like your camera is focusing okay. I think the problem you are experiencing is cause by the lens. Your data states "55mm @ f/5.6" so I assume you are using the 18-55 Kit lens. This lens isn't that great wide open ( max aperture) Try setting the aperture to f/8 and your results should improve. If you are using handheld make sure the Shake Reduction is on and if your shutter speed gets below 1/30s I would recommend a tripod. If you use a tripod, make sure you turn the SR off.

Swift1

Edit: Just noticed you had listed what lens you used.
02-07-2010, 11:18 PM   #3
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Hi:

You state you are 25cm from the subject. That, I believe, is too close for that lens, though I do not have the specs in front of me. If it is not too close, it sure is close to the lens' limits, so back up a bit. Also, you are shooting wide open, up close, which makes depth of field very narrow.

So, back up a bit. Then shoot @ f8--you have a tri-pod. Go into manual mode and set aperture for f8, and increase shutter length by a full stop too. If your lighting is the same, this should work because the shots you posted are okay for exposure.

More specifically, back up a foot, go to f8 @ 1/60th of a second--tells us how you make out.
02-07-2010, 11:20 PM   #4
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Thank you Swift1 for your swift reply.

I will try to reshoot tomorrow using the same set-up as I used above but closing down the aperture to f/8 as you suggest and see what the results are. The printed test I used specifically requested opening to the largest possible aperture - which I suppose was only useful in gauging front/back focus issues.

Thank you for your help.

Byrnsy

02-07-2010, 11:30 PM   #5
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Thanks Jewelltrial

I will use your suggestion as well as Swift1's when I try to reshoot tomorrow. There seemed to be no problem with my lens finding focus but I will see if it's any better from further away.

Although I was shooting wide open, I still cannot see any part that is precisely focused - especially in the shots of my jewellery.

I'll get back with my results tomorrow.

Regards

Byrnsy
02-08-2010, 12:00 AM   #6
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QuoteOriginally posted by byrnsy Quote
I still cannot see any part that is precisely focused - especially in the shots of my jewellery.
We can't pixel peep such a small image so it's hard to tell but if you do with the originals, I think you might find that the top of the connecting rings are in focus.

In the second shot, the coins look pretty well focused as well.
02-08-2010, 06:20 AM   #7
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This is mostly a depth of field issue. As mentioned above, some of the image is in focus (the lower coins) while some is not (the upper section). If you close up the aperture a bit, more of the picture will be in focus. The closer you are to your subject, the narrower the depth of field. Someone mentioned backing up, and that's a good idea. Don't be afraid to crop your picture after you've taken the shot to get rid of the extra stuff around your subject. There are plenty of megapixels to play with here.
02-08-2010, 06:47 AM   #8
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Byrnsy,

as the previous contributors have noted, you are too near to the test chart and the humble kit lens has an official minimum of these 25cm. So you do not leave any distance at all for the lens to adjust focus!

Also, at these short distances, these simple zooms usually perform far worse than focused a bit farther away. This is the reason (as it is valid for most lenses, ecept macros), why lens testing is usually done at at least 20-100 times the focal length.

Then there is the question of the shallow depth of ield and the wide open aperture, as has been already stated.

And lastly I want to add, that these focus charts are more or less meaningless. As you can see, it expects the camera to focus onto that black line in the centre of the chart. As nobody actually knows, where the central focus point is pointing to (the small illuminated rectangle is only a very rough approximation) and the AF point is bigger anyway, these charts are misleading: the AF point often simply doesw not lock onto the focus line, but a bit obave that (mostly) or bewlow. In these cases it seems, the lens is misfocusing.

The only valid test targets ar completely plano-parallel to the camera sensor, i.e. the famous brick wall.

It sure takes more time to test a camera against a parallel brick wall, as you have to make many test images, instead of the seemingly convenient scale on those charts, but the wall is reproducable and will be realiable even if the real AF point is far off the viewfinder symbols.

Ben

02-08-2010, 07:22 AM   #9
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QuoteOriginally posted by Ben_Edict Quote
And lastly I want to add, that these focus charts are more or less meaningless. As you can see, it expects the camera to focus onto that black line in the centre of the chart. As nobody actually knows, where the central focus point is pointing to (the small illuminated rectangle is only a very rough approximation) and the AF point is bigger anyway, these charts are misleading: the AF point often simply doesw not lock onto the focus line, but a bit obave that (mostly) or bewlow. In these cases it seems, the lens is misfocusing.

The only valid test targets ar completely plano-parallel to the camera sensor, i.e. the famous brick wall.
ooh, you just brought up something that's been bugging me for a while, but I'm not sure if it' appropriate for this thread (or this section of the forum), so I'll start a new thread instead:

https://www.pentaxforums.com/forums/pentax-dslr-discussion/89665-focus-focus-...tml#post912432
02-08-2010, 12:04 PM   #10
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QuoteOriginally posted by Ben_Edict Quote
As you can see, it expects the camera to focus onto that black line in the centre of the chart. As nobody actually knows, where the central focus point is pointing to (the small illuminated rectangle is only a very rough approximation) and the AF point is bigger anyway, these charts are misleading: the AF point often simply doesw not lock onto the focus line, but a bit obave that (mostly) or bewlow.
Only if you come in at too steep an angle or shoot from too far away. If you set the test up *correctly* - such that there is nothing else but the line itself t=within range of the focus sensor - then it is basically foolproof. Although it doesn't account for the field curvature of the lens - as a result what appears from looking at the sides to be slight front focus might actually be correct. Also, with a wide angle lens that doens't focus particularly close - well, any lens that works out to a poor magnification ratio - you might not be able to get everything else out of the way of the focus point unless you print the chart out bigger than the default. But still, used properly, it works perfectly.

Anyhow, it's pretty clear there is no front or back focus problem here - it is simply a case of DOF not being deep enough to encompass the entire object being photographed, as the first images makes quite clear (both the front and back are OOF). You need more DOF, period - and the only way to get that while maintaining the same magnification is to use a smaller aperture, period. If you back up farther and then use a longer focal length to fill the frame again, you're right back where you started.

Last edited by Marc Sabatella; 02-08-2010 at 12:10 PM.
02-08-2010, 04:01 PM   #11
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what do you mean by "sharp"?

The other suggestions made already all seem sound to me and I urge you to try them out. However, this issue of "sharpness" has a number of hidden complexities and you might either be confusing one thing with a number or (more likely) expecting more than you should from your camera.

Sharpness isn't just a matter of proper focus. Some lenses are simply "softer" than others. This isn't even necessarily a bad thing. The kit lenses sold with Pentax cameras are perfectly decent lenses and I've seen wonderful photos taken with them. But these days we sometimes see photos that are unnaturally sharp - and they affect our notion of what we should be expecting. Somebody in this forum has or used to have a wonderful signature line: "We live in the age of the oversharpened image." It's true.

Anyway, after you try the simple technical things that others have already suggested, I would suggest that you lower your expectations just a little. You don't need to be able to cut yourself on an image. You only need it to be sharp enough. Consider viewing your photos as good quality prints rather than on your computer. I think prints are the better test of an image's clarity.

To take better, sharper - or as I prefer to say, "clearer" - images, there are a couple other things you can try.
  1. Figure out where the lens's sweet spot is. For zooms, I think it's often in the middle of the zoom range, and it's usually NOT wide open. If it's an 18-55 f/3.5-5.6 lens, try shooting around 33mm and f/8 and see if it helps.
  2. Get a better lens. At around 33mm, you should expect better results from, say, the Pentax 16-45 f/4 than you're getting from the kit lens. The Pentax 35 f/2 or 40 f/2.8 should be even clearer. And the Pentax 31 or 43 primes should blow you away. Alas, the 31 and 43 are rather pricey.
  3. IMPROVE YOUR LIGHTING. Actually this is usually the easiest thing you can do to improve your images. Make sure you have plenty of light.
  4. Leave the in-camera defaults for sharpening and contrast alone and instead, learn how to use the sharpness or clarity tools in your post-processing software. Raw images especially almost always require some sharpening after capture, and even jpegs can sometimes benefit from careful sharpening. It takes a little knowledge, a lot of practice and a degree of good taste to learn how to sharpen images on the computer without overdoing it.

Will
02-08-2010, 09:46 PM   #12
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QuoteQuote:
Marc Sabatella: If you back up farther and then use a longer focal length to fill the frame again, you're right back where you started.
Marc, the OP shot at 55mm, how can they "back up and use a longer focal length to fill the frame"?

Marc Sabatella: .... it is simply a case of DOF not being deep enough to encompass the entire object being photographed, as the first images makes quite clear (both the front and back are OOF). You need more DOF, period - and the only way to get that while maintaining the same magnification is to use a smaller aperture, period.

It is also a case, clearly, of the lens being at the limit of its close focus abilities. Everyone agrees DOF is an issue, but backing up and stopping down would address both issues of concern. BTW, nowhere does the OP mention any desire to maintain the "same magnification."

QuoteQuote:
Marc Sabatella: Anyhow, it's pretty clear there is no front or back focus problem here -
I do not see how that can be concluded from the limited information the OP provides in this thread.
02-08-2010, 11:01 PM   #13
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QuoteOriginally posted by Jewelltrail Quote
Marc, the OP shot at 55mm, how can they "back up and use a longer focal length to fill the frame"?
Not with the kit lens, obviously. I was just commenting the advice I had seen given previously.

QuoteQuote:
It is also a case, clearly, of the lens being at the limit of its close focus abilities.
Perhaps, but given that the back of the item is not in focus either, that doesn't seem to be the most relevant problem to me. I suppose it's possible this is limiting things at the front end too, but I don't see any proof of that.

QuoteQuote:
Everyone agrees DOF is an issue, but backing up and stopping down would address both issues of concern. BTW, nowhere does the OP mention any desire to maintain the "same magnification."
True. But I assume the OP framed the picture this way for a reason, and he wants to take a similar picture - a product shot. Backing up would increase DOF, but *if* the OP then went to a longer focal length to compensate, you'd not get any advantage. I just wanted to clarify that in case the OP was thinking of trying that.

QuoteQuote:
I do not see how that can be concluded from the limited information the OP provides in this thread.
I see a focus test chart image that looks fine.
02-09-2010, 12:02 AM   #14
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QuoteQuote:
byrnsy: b. Camera on tripod at a 45 degree angle to subject and approx. 25cm from subject.
Note the use of the word approx in the above quotation. And note the close-focus specs of our Kit lens, from our Lens database in the below quotation:

QuoteQuote:
SMC Pentax-DA 18-55mm F3.5-5.6 AL II:Min Focus 25cm
QuoteQuote:
Marc Sabatella: Perhaps, but given that the back of the item is not in focus either, that doesn't seem to be the most relevant problem to me. I suppose it's possible this is limiting things at the front end too, but I don't see any proof of that.
We are not arguing degree of relevancy here; rather, we are summing up the contributing factors in the image not all being in focus--this is the OP's concern. The word you use above, "perhaps," is a step down from your original language here:

QuoteQuote:
Marc Sabatella: it is simply a case of DOF not being deep enough to encompass the entire object being photographed, as the first images makes quite clear (both the front and back are OOF). You need more DOF, period...
I am not trying to be pedantic--I am trying to point out that our concern with the lens being at its close focus limits is valid, and worthy of discussion in this thread. Ben's advice is particularly pertinent here:

QuoteQuote:
Ben_Edict: Also, at these short distances, these simple zooms usually perform far worse than focused a bit farther away. This is the reason (as it is valid for most lenses, ecept macros), why lens testing is usually done at at least 20-100 times the focal length.
02-09-2010, 12:11 AM   #15
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Firstly, thank you to everyone that has offer me advice in this thread. Forgive me for not quoting you individually for your suggestions - but perhaps I can when I'm more familiar with posting on the forum. To be honest I'm finding the conversations between some of you very informative but also overwhelming. I am trying to get my head around all the information relevant to me and I will also try the "Brick Wall" test when I can get time (and a brick wall!).

I will also add that I've thought the photos I've taken since owning my K10D were all a little too soft but as suggested, perhaps I have to change my expectations as well?

I have just finished taking some more pictures using the basic suggestions that most of you kindly offered. I also attached 2 of my other lenses to see the results. I am having trouble working out how to post the pictures with the relevant information attached, so I will post this first then the pictures individually.

Byrnsy
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