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06-16-2019, 08:38 AM   #1
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Impossible to get good sharpness żis it the camera, lenses, focus, me...?

Hi everyone,

I suppose is a very common issue for beginners and there's a lot of information on the Internet, but I have read a lot about it and I still can't find a solution.

I got a second handed K-x N73 camera with two lenses 18-50 and 55-200, both Sigma. I was wondering if there is any way to find out why my pictures have not a good sharpness. I am not sure if is a problem with the camera, the lenses (would be extrange to have same problem in both lenses) or just me doing the shot wrong. But I have tried everything, every Internet tip, every way to shot, even bought filters and cleaning kits and my smartphone pictures still have better definition. So there's no point to carry my camera. I am very disappointed because I thought is a good camera and I like photography and would like to take good pictures with it but I am a mountain guide so my specialty will be landscapes and the sharpness is very important.

Thank you very much in advance for any help!

06-16-2019, 09:11 AM   #2
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The best way to get reliable feedback would be to upload some pictures with intact EXIF data so we can see the parameters that were chosen when the shots were taken
06-16-2019, 09:20 AM   #3
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QuoteOriginally posted by ehrwien Quote
The best way to get reliable feedback would be to upload some pictures with intact EXIF data so we can see the parameters that were chosen when the shots were taken
What he said^, many of us are skilled at diagnosing what's wrong with images. Many of us have problems diagnosing problems form verbal descriptions. Especially with inexperienced photographers, they often have not identified the problem correctly.

There are a number of possibilities.

Motion blur caused by camera movement.
Motion blur due to subject movement due to subject movement.

Both of these can be affected by increasing the ISO and thereby the shutter speed. Although in some cases a tripod will be necessary.

Camera is front or back focusing. ( You have to learn to calibrate your lenses.)

Lens is decentered. ( One side is soft, one side isn't. There is no known solution to this problem apart from disassembly and randomly inserting shims, using trial and error.)

Also, too high an f stop can cause softness due to diffraction.

We won't know what we're looking at until we're looking at it.
06-16-2019, 09:29 AM   #4
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QuoteOriginally posted by normhead Quote
Camera is front or back focusing. ( You have to learn to calibrate your lenses.)
Which is a problem with the can only adjust lenses in debug mode.

K-x debug mode w/pics please -

06-16-2019, 10:31 AM   #5
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And do you wear glasses? Are you manually focusing or automatic focussing?
06-16-2019, 10:34 AM   #6

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Yes, can't say without examples or knowing what you are looking it. It could evan be the pictures are fine but you are looking at RAW images and are used to looking at sharpened processed jpegs. (Although I must say out of the camera jpegs look great from my Pentax cameras -- sometimes it is hard to get the RAWs looking so good.)
06-16-2019, 11:37 AM   #7
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Thank you very much for all the answers, I don't wear glasses and I am using autofocus, but I have also tried manual focus and all kind of focus adjustments.

Find attached four examples taken right now, same place, all of them ISO 400 and lens in 28mm (sigma 18-50). They are the jpg converted by the camera in best quality jpg mode.

IMGP2809: 1/125 F8.0
IMGP2811: 1/40 F18
IMGP2812: 1/20 F18
IMGP2814: 1/10 F29

Thank you very much!!
Attached Images
View Picture EXIF
PENTAX K-x  Photo 
View Picture EXIF
PENTAX K-x  Photo 
View Picture EXIF
PENTAX K-x  Photo 
View Picture EXIF
PENTAX K-x  Photo 
06-16-2019, 12:10 PM   #8
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QuoteOriginally posted by mgisbert Quote
Find attached four examples taken right now, same place, all of them ISO 400 and lens in 28mm (sigma 18-50). They are the jpg converted by the camera in best quality jpg mode.
Welcome to the Pentax Forums!

What was the intended point of focus?

Part of the problem might be the narrow aperture. While depth of field is greater as the aperture becomes narrower, there is degradation of sharpness that happens as well due to diffraction. The point at which diffraction becomes significant (i.e. diffraction limited) varies by pixel size on the sensor and, by extension, sensor size and final display size. Your K-x will likely be somewhat diffraction limited at f/11 with progressively poor acuity at apertures narrower than that.


06-16-2019, 12:58 PM   #9

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What Steve said ^. Keep in mind, a higher aperture number means closing it down to a narrower value, letting in less light. A lower number to the degree your lens will go, means opening the aperture more, which lets in more light. This will allow a higher shutter speed in the same lighting, which if lighting is dim will be important, since this can prevent shutter speed from getting too low for moving subjects or from your own body's slight movement, and will result in blur in your shots.

Conversely, a closed-down aperture will allow much less shutter speed in getting correct exposure. Then you may get a shutter speed too slow for getting sharp photos with a hand-held camera. And too slow to freeze movement. And if the aperture is closed down more than f/11 the degradation of quality due to diffraction, as Steve alludes to, will become an increasing factor the more the aperture is closed down. (a common characteristic in the optics of lenses)

The central tree in your first photo is quite sharp. Shutter speed is a very reasonable 1/125 sec and good for hand held shots when not using a long telephoto lens, and good enough for the tree if the wind is not blowing at a high speed. And the aperture is near optimum for quality at f/8. The trees in the background are not in focus, therefore not sharp, because they are too far behind the focus point of the lone tree being focused on.

Having a narrower aperture does increase depth of field (DOF) so more of what is in your frame will be in decent focus and therefore sharp, so perhaps shooting the scene at f/11 would have brought those background trees into better clarity without too much loss due to diffraction. However, as a composition the photo as is would be seen by most as the better choice. Having some blur in the background makes the chosen subject- the lone tree, stand out more.

The other photos were taken with an aperture way too closed down, such as f/18 with attending diffraction, and also with the attending necessary very slow shutter speed, which from your body's natural slight motion and the wind's effect on the trees, is insufficient to freeze these movements.

When shooting in Manual mode, these are things that must be taken into consideration. There is a technique called establishing the hyper-focal focus point for maximum DOF, which is another discussion. If you shoot in the "P" (Program) mode, the camera will choose both aperture and shutter speed. It usually does a good job compromising these factors.

In the SCENE modes, which your class of camera probably has, there will be convenient choices to fit various circumstances, such as action scenes where the camera will choose settings emphasizing faster shutter speeds, or a landscape mode where the camera will choose settings emphasizing DOF. You might try these out to study what the camera is doing, keeping in mind the above info I've provided. Then you will be better equipped on an entry level to operate in Manual mode and having some idea of what you are doing and why.

Also, if your camera has this feature, for good out of camera JPEGs, be sure to establish "Fine Sharpening" in the Custom Image menus, especially in the "Bright" category, which is used most often.

Last edited by mikesbike; 06-16-2019 at 07:48 PM.
06-16-2019, 01:54 PM   #10
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Thank you very much for the answers.

I knew that to get a big DOF for landscapes I should have a big aperture but I understand of what you are saying that the limit for my K-x should be F11, right? I will try to do that even with a tripod to see if I can get better results and I'll show you but to be honest I don't have big hope to get better pictures than with a smartphone. I wonder if there's any other adjustment or option (I can't find that "Fine Sharpening" you mentioned mikesbike).

By the way, I'm really happy to be learning all this things, maybe just improving myself as a photographer can be useful to get better results. Perhaps is just a problem with landscapes because I would like to have everything clear and nice and that's more complicated than other pictures like this one I show here which looks quite sharp.

Thanks a lot!
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06-16-2019, 01:59 PM   #11
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The first shot was with an aperture of f8 (which should be fine for sharpness if there is no motion blur), but the subsequent shots were at f18 and above which will not resolve as sharply due to diffraction. In general for best sharpness (with those lenses you have that is) you probably want to be around f8 (or maybe f11). Also the later images are shot at quite low shutter speeds which may result in blur due to camera moving (unless they were shot on a tripod?).

That said I don't see anything wrong with the photos at that size. It depends what in the image you were intending to be in focus? Keep in mind with much a bigger sensor than a mobile phone, you are dealing with shallower depth of field - which can also be a strength as it gives you more control of the image you capture. To maximise depth of field then you probably would want to shoot at or around f11 (f16 max) and either shoot on a tripod or set the ISO high enough to get a higher shutter speed high to avoid blur from the camera moving (at say 28mm you would ideally want say 1/60 or faster for hand held)

Getting a DSLR can be a bit of a learning curve but there is great potential to create much better photos (and have a lot of creative fun). There are lots of great resources online, for example to get a sense for depth of field have a play with a simulator like:
06-16-2019, 02:48 PM   #12
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For landscape photography especially you should read about hyperfocal distance. You've already gotten some advice on choosing the best aperture and using a tripod to eliminate any potential for softness caused by your own movement. This will also allow you to use the lowest ISO (higher ISO will also reduce the detail in your pictures).
You should also know that most of the time zoom lenses will not be as sharp as prime lenses, and zoom lenses are often softer at their extreme focal lengths. Using 20 or 24 mm instead of 18 might give you a little boost in sharpness, but that depends on the lens.
Regarding the process of focussing itself, you will achieve the best results when using the central focus point and confirming the sharpness while zooming in in live view, if your camera supports this.
06-16-2019, 05:16 PM   #13

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Some words of encouragement - the K-x is a good little camera that is perfectly capable of taking great, sharp images, including landscape.

Re the problem you've identified, if simple motion blur or the wrong aperture settings is not the culprit, I suggest doing what you can to separately test (a) lens and (b) camera AF.

To start, in good, bright light, prepare a totally flat non-3D test scene with lots of detail in the middle of the scene (even a newspaper page stuck on a wall will do). Then use a tripod (dont forget to turn off the camera's shake reduction if you are using a tripod), arrange your camera and lens to point to the direct centre of this test scene, and set a focal length in the middle of the zoom range of your 18-50 lens (eg 28-35mm).

Set the camera exposure mode to Aperture priority (Av), and set the aperture to a maximum of f8 (no need to use f29 or f18 like in your posted images). Or simply set your camera to 'AUTO PICT' (Auto Picture') mode and let the camera handle most of the settings.

Then, (a) test the lens:

- switch on Live View and manually focus the lens until the subject looks sharp on the rear LCD screen. Press the INFO button in LV to enlarge the scene to check focus in detail, if desired. As you prepare the shot, if possible try to keep the ISO being used lower than 800 ISO and your shutter speed higher than 1/125. Then gently press the shutter and shoot a few shots. (Ideally, trigger the shutter with the camera's 2 or 12 second self-timer, to minimise camera shake). Review the results on your computer to see if the scene looks acceptably sharp.

Next, (b) test the AF:

- initially, use LiveView to do the AF tests. Turn on LV, set the focus mode lever to AF, select Contrast AF as the LV Autofocus mode, and then shoot a few images.

- then test 'normal' viewfinder AF by turning off LiveView, setting the focus mode lever to AF, the AF mode AF.S, the focus area to Auto 5 (the default), and then shoot.

See which tests produced the sharpest images. If manual focus using LV fails to produce acceptably sharp images, the lens may simply be not great or be dirty or damaged. However if the same lens produces sharp images manually focused in LV, but using LV AF or normal viewfinder AF does not produce sharp results, then something may indeed be amiss with the camera AF, or your settings or technique.

If the AF works bad when using viewfinder AF, but not LV AF, there is the remote possibility that the AF assembly in the body has some crud in it or has taken a knock. It might help to give the interior of the camera an inspection, and if dust or crud are apparent, gently clean around the bottom of the mirror box with a rocket blower.

A further test may be to simply try another [non Sigma] AF lens. Or if you suspect that your lenses are just soft, get a clean manual focus prime lens that's known to be sharp (eg M 50 f1.7) and shoot some tests. You could also mount your current lenses on another Pentax to see how they work there.

The simplest fix worth exploring, of course, may be to remove any UV or protection filters from your lenses (if you have them fitted). They reduce the optical quality of a lens (some are truly awful) and sometimes they can interfere with AF too.
06-16-2019, 06:38 PM - 1 Like   #14
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Grass like you've shown can be very difficult to photograph since it moves more with tiny bits of wind than almost anything manifesting as motion blur at even moderate shuttterspeeds, and doesn't look great when it does.
06-16-2019, 08:33 PM   #15

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Do you have an owners manual for your K-x? I've never owned one, so I looked it up via google and the Ricoh customer support site for downloading manuals. Once I got to the manual, I found the info for going into the Custom Image menus, which have to do with the image finishing tone and numerous other matters. first have your camera's mode dial set to Manual or to the "P" mode. Then, as with many other Pentax models, you can press the info button and bring up a control panel screen, which provides direct quick links to various sections of function to make adjustments, without having to pan through everything if using the menu button. The 4 buttons surrounding the ok button will now serve for navigation. The first section will be the Custom Image one, and most likely it will already be selected, since it is first. (while you are at it, take a look to see that your camera is set to the highest 3-stars JPEG quality, shown among other sections in this control panel screen)

Hit the ok button to open this section, where the first will likely be the "Bright" category. Hit the info button to access it for making adjustments. Tab down to Sharpening, and use your thumb dial to put an "F" by the "S" for "fine Sharpening". You are done, so hit the ok button and turn off the camera which will vacate the screen.

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