Is this normal noise/sharpness for K5/Kit lens?

Started Apr 22, 2012 | Discussions
SenorBeef
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Is this normal noise/sharpness for K5/Kit lens?
Apr 22, 2012

I've got a new K5 and right now I only have the 18-55WR kit lens. So far the image quality has not impressed me terribly well - noise kicks in at a lower ISO than I'd expect, and there's just that not much detail in some parts of the image.

So I'm wondering if there's something wrong, or if I'm just expecting too much out of the kit lens, or if my expectations about image quality in general are too high.

I've used the straight out of the camera JPEGs so that my skill at PP isn't a factor, but I do have the RAWs if you want to see those.

The first image is a crop from a portrait. The Iso is only 640, which should have very low noise, yet the background seems pretty noisy to me. The out of focus areas are worse, but even the in-focus arm has a lot of noise. I've seen images on this forum where 3200 and 6400 ISO shots look a lot less noisy than this image at 640 iso. Is it their post processing skill at work?

Next up is what I'd consider one of my sharper pictures. Viewed at small size, it looks pretty good, but zoom in and it just seems like there's a general lack of sharpness and detail. It's about as good as my Canon SX230 small sensor camera, and that camera isn't known for having an especially sharp lens or sensor. I expected better from a SLR, even with just the kit lens.

Below is a crop to show what I mean.

Here's another one where the sharpness on the rocks looks okay at lower res, but the patterns in the water look strange, especially when viewed close up. There's just not that much detail there. I know this picture is overexposed.

Is this normal output for a K5 and 18-55?

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mike703
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

I don't know what is normal for a K5, but that looks to me like a combination of red-channel noise plus over-sharpening.

On areas of a pic that are more or less blue or green primary colours (like skies and seas for blue, or areas of foliage for green) there is essentially no red information. So noise in the red channel will stick out like a sore thumb, and the red channel is inherently noisier than blue and green anyway. (An analogy: a small amount of hiss from an audio system will not be noticeable when there is loud music playing, but will be very obvious on top of complete silence). It is very common to see more noise in smooth blue or green regions of a shot than anywhere else:

http://forums.dpreview.com/forums/read.asp?forum=1032&message=31093852

If you have sharpening set to high in the camera that will exaggerate the effect: the worst thing you can do to noise is sharpen it, because sharpening boosts differences at high contrast edges and therefore makes noise look worse. If you shoot RAW, do noise reduction first and sharpening last, and then the results will be much better. Check your camera jpeg settings...

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awaldram
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

Taken in order

1 under exposed noise is about right for the exposure to the left
2 highway more difficult but looks like some camera movement to me.

3 Sea looks strange, for 1/125 the sea looks exactly right with some smoothing of the breakers as they are moving.

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SenorBeef
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to mike703, Apr 22, 2012

The JPEG settings are all default (except I changed the quality from 3 star to 4 star) - but no sharpening adjustments.

It doesn't seem over-sharpened to me simply because it seems to be relatively unsharp and lacking detail everywhere.

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SenorBeef
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

I forgot to add that it's calm Lake Meade behind me rather than any sea - that's definitely relevant if you're trying to figure out if the shutter speeds play into how the water looks.

What do you mean the noise looks right for exposure to the left? It was set to full scene metering and EV0 on AV mode, so I wasn't underexposing... or are you saying the meter was wrong and it underexposed?

In any case, since I wasn't adding any brightness in PP, shouldn't just the ISO level be relevant to the noise?

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mike703
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

default sharpening will still amplify noise. At ISO640 I'm not surprised to see a little noise in the shadow areas - on my K7 noise like that is visible at ISO400; Adobe Camera Raw cleans it up nicely. An external noise-reduction programme will do a much better job of noise reduction than the camera. If you really want to avoid that level of noise, use 1/125 sec instead of 1/500 sec and you can use ISO160 instead of 640.

The nice pics you have seen at ISO 3200 were probably not 100% crops. That's an important point - when you are looking at a picture as a whole the 100% crop view is irrelevant - it is a massive magnification. You will see noise at ISO 100 if you look hard enough, it is always (and inevitably) there... I'm willing to bet that in an A4 print of your portrait shot the noise is completely invisible

Those high-ISO examples will also have been PP'd using something like Topaz DeNoise, NeatImage or whatever. The pics from your little compact that have more 'pop' to them will have been over-saturated and over-sharpened in the camera which is typical for compacts... they will have less detail in them!

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awaldram
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

SenorBeef wrote:

I forgot to add that it's calm Lake Meade behind me rather than any sea - that's definitely relevant if you're trying to figure out if the shutter speeds play into how the water looks.

It doesn't really natter where the water is its moving I can see that and its smoothed consistent with what a 1/125 shutter would do.

What do you mean the noise looks right for exposure to the left? It was set to full scene metering and EV0 on AV mode, so I wasn't underexposing... or are you saying the meter was wrong and it underexposed?

No I mean the portion of the image is under exposed that not a camera issue.

Correcting and applying a smidgen of chroma clean up and you can see in the black T-shirt the sensor received no signal at all !! i.e all noise.

That why it now looks posterised, The RAW probably had some shadow detail but the 8bit Jpeg has lost it.

In any case, since I wasn't adding any brightness in PP, shouldn't just the ISO level be relevant to the noise?

No noise is relative to the signal received , So noise is constant but signal varies.

If you under expose you supply very little signal and it gets swamped with noise.

Full scene metering will protect the highlights of the whole scene so the sky being bright will define the maximum exposure.

If your intent was to get you subject exposed correctly then Spot or partial was the appropriate metering scheme not full matrix.

If you wanted to get as much of the scene within the exposure then you needed iso 80 to leverage the max DR of the camera or switch to a HDR mode.

The camera has done exactly what you told it todo.
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Gerry Winterbourne
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

In the first shot, taken at f/5.6, most of the crop you've posted should be outside the DOF if you were focused on the figure in the portrait. The figure itself is too dark ro judge how sharp it is. As this is only a crop it's impossible to say if exposure was correct but the bit you've shown looks underexposed.

In the other shots shooting at f/11 has lost a bit of sharpness compared to f/8 or f/5.6 but not enougfh to look as soft as they do. It looks as if you might have a bit of front focus but the shots you've posted are very much separated into near, mid-range and distant so it's hard to be sure.

I don't usually use zoom lenses but I tried out the 18-55WR on my K20 and K-7 (which have a touch less resolution than the K-5) and got much better results than these. I suggest you try a bit of calibration of the lens-body combination.

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DAVID MANZE
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

Hi Senorbeef,

No, your photos don't look that sharp, take some pictures at full aperture in Live View and check the results for sharpness( landscape scenes are ideal as infinity shows up problems quickly) LV autofocus should be accurate as it uses the actual sensor. If there are differences,use the AF adjustment in the menu until the 2 systems correspond.

Take a series of test shots at all apertures and all focal lengths, preferably at infinity (landscape), so as see if the lens is performing correctly, at full apertures any decentering of the lens will be obvious(sharper one side than the other) if there is a problem with the lens I would return it,to be repaired or replaced.

While the photos seem a bit noisy, this is not so surprising with such large areas of dark shadows with no detail, out of focus areas look more noisy than sharp ones. Noise can often be visible even at low ISO settings in the shadows, whites that are heavily shadowed often show noise at 200 ASA. In images with shadowed areas at 640 ASA I would normally use a bit of noise reduction ( I'm talking about PP in RAW). Lastly, try not to underexpose, as a 1 stop underexposure at 640 ASA produces as much noise as at 1280 ASA.

Keep fine tuning, we all read about low noise in the K5,but it takes correct technique to get it at high ISOs.
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SenorBeef
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to DAVID MANZE, Apr 22, 2012

Here's the original image from the portrait. I didn't want to post it since it's a bad pic, but if it'll help evaluate the noise:

Also, if it'll help to identify potential focus issues, here are 2 shots where the focus is more clearly defined:

On the second pic, I tried to focus on the guy jumping, but I'm not 100% sure what the camera picked to focus on. His face seems a little out of focus.

How exactly does having a front focus problem at infinity work? Can someone explain it to me? Does it mean it's focusing at some fixed distance, and therefore everything at infinity is out of the clearest part of the depth of field?

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mrdc76
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

SenorBeef wrote:

How exactly does having a front focus problem at infinity work? Can someone explain it to me? Does it mean it's focusing at some fixed distance, and therefore everything at infinity is out of the clearest part of the depth of field?

Cameras always focus at a fixed distance, so to say, but front focus just means that the camera focuses in front of the subject. So yes, if you are focusing too close, everything at infinity will be out of the depth of field, even if you have stopped the aperture down to f/11 - which you generally speaking should not do with a 16 megapixel camera (unless you really want to maximize the depth of field and are prepared to lose some sharpness due to diffraction).

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awaldram
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

In that first image the cmaer has correctly exposed for the while image.

I somehow suspect this was not how you envisioned the result.

It is a partial contra jour type image

http://en.wikipedia.org/wiki/Contre-jour

As I said HDR would have recovered the target, But in this case I suspect popping up the flash for a bit of fill would have delivered what you expected.

The player shot is spot on I see no issues and actually really like the shot.

The jumper Is slightly front focused (note the basket is sharp) but they have been a result of positioning rather than and intrinsic calibration error in the Phase detect AF

If you have concerns then you need a tripod to do anything resembling decent AF calibration.

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Gerry Winterbourne
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

There probably isn't a lot wrong with your lens looking at these shots: possibly, as I said in my previous post, a small amount of front focus. What this means is that the AF sensor tells the lens to focus at a given distance but the lens actually focuses a bit nearer than that.

Take you shot of the jumper: the exact centre of the frame is his shirt. The centre AF sensor is actually a cross with its arme about as long as the circle in the VF. This means that the sensor would see the high-cpontrast transition between his shirt and the background; his arm; and the high-contrast join between his shirt and shots. All of these look pretty crisp to me (you should look at the full size version on your computer) but the chains on the basket seem a bit closer and they are crisp too. This suggests that the camera is focusing just a little bit in front of where it should.

As suggested elsehere, do some more rigorous tests before you start adjusting.

The other shots here look OK but there's nothing in them that would show up a bit of FF.

Here's your portrait opened up. As you see, the details in the face are reasonably crisp but, again, you'd need the full size version to be sure. Bear in mind that the ISO you used plus opening up gives quite a lot of noise, which makes the image look relatively soft regardless of focus.

I've analysed the histogram for this shot and its average value is 103 (for a full range of 0 to 255). Increasing exposure by 1/2 a stop lifts the average to 122, which is very close to the mid-point value of 128. In other words, based on a strict averaging of the light the camera metered by 1/2 stop underexposed. However, the very brightest patch of sky clips with just a touch more exposure so the metering was obviously protecting the highlights. The version I've put here has an average of 142 because I opened up the shadow areas. (By way of comparison your jumper shot averages 79, presumably because the camera was protecting the shirt; but because the main subject isn't in shadow it looks fine).

For this type of shot you should use centre-weighted or even centre-point metering. That might cause the sky to clip to white but at least you'd see the face properly. Or, of course, learn some PP so you can do what I've done.

That shot was taken at ISO640 and 1/500s; with ISO80 and 1/60s you'd have had exactly the same exposure and far less noise. You can't always use ISO80 but it's a good idea to use it whenever possible and only go higher if you are forced to do so.

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BobORama
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

Hi,

The first shot seems to be y-axis shake, this is easily seen on the white concrete barrier sections where there is a pronounced vertical ( but not horizontal ) blur.

I find that for a kit lens the 18-55 performs very well.

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SenorBeef
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to BobORama, Apr 22, 2012

Is front focus always a lens issue?

Basically I'm trying to figure out if there's anything wrong with my camera. I'm coming up on the date I can return it. Between the lens price increase, an incorrectly calibrated horizon level, and the fact that most of my pictures so far can't even beat my point and shoot I'm considering going a different direction. But I'd like to know if you guys can tell me if you think there's a problem with the camera or lens.

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Marc Sabatella
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 22, 2012

SenorBeef wrote:

Is front focus always a lens issue?

It's essentially never a lens issue, and there is no evidence whatsoever you have a FF problem anyhow. Any time focus isn't exactly wher you expect it, people always rush to blame the equipment, but there is no possible way anything in any of these images would be explained by front focus.

It's really quite simple. Your images of rocks and water cannot possible have both in focus. Either the rocks are in focus or the water is; take your pick. I'd say the rocks are, meaning the water is simply out of focus because depth of field is never large enough to encompass an entire image, especially not when pixel peeping.

The image of the basketball player standing still is proof positive your camera is functioning just fine. The players moving are a little soft, but what did you expect? They are moving .

Your point and shoot has lulled you into expecting much larger DOF than most people would consider aesthetically pleasing, and into being lax about exactly where you focus. An SLR allows you to achieve much more aesthetically pleasing pictures by allowing backgrounds to go out of focus, but in return, that means you have to be careful about where you focus.

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steephill
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In reply to Marc Sabatella, Apr 22, 2012

Are you using SR? Are you waiting until the image is stabilised before taking your shot? You can examine the exif data from your original shots to see if this is the case, unfortunately the images you have posted have had some of the exif data stripped out so I can't tell.

When I got my first SR capable camera I got a lot of disappointing shots until I realised that I was consistently shooting too soon.

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SenorBeef
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to Marc Sabatella, Apr 23, 2012

Marc Sabatella wrote:

SenorBeef wrote:

Is front focus always a lens issue?

It's essentially never a lens issue, and there is no evidence whatsoever you have a FF problem anyhow.

This confuses me. People talk all the time about how they kept sending lenses back to get a good one because they had front focus and back focus issues.

Your point and shoot has lulled you into expecting much larger DOF than most people would consider aesthetically pleasing, and into being lax about exactly where you focus. An SLR allows you to achieve much more aesthetically pleasing pictures by allowing backgrounds to go out of focus, but in return, that means you have to be careful about where you focus.

I get that, but it's not just that. Even in pictures that seem are properly focused, like the bridge/desert freeway one, there's just a general sort of lack of detail, compared to the other pics I've seen here. And upthread, other people have said they've done much better with the K5/kit lens combo. So it makes me wonder why my pictures are worse. Someone upthread ventured a guess - that that particular seems to have vertical motion blur - but even then, I took the picture with stabilization on, with a pretty normal shutter speed, so I don't know how that could be the case.

Basically, I'm coming up on the closing window to where I can return the camera to the retailer rather than have to deal with Pentax's crappy support, and I'm hoping someone can tell me if something is defective with my lens or camera. Since other people talk about having gotten much better results, I wonder if there's something there.

And yeah - to the other poster, I know SR takes a second to kick in, I don't shoot until the little hand is in the viewfinder.

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mrdc76
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 23, 2012

Take another set of landscape pictures, by using wider apertures than f/11, and post the results here in the original size. If possible, use a tripod, 2 second timer and focus manually by liveview into distance.

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hanhait
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Re: Is this normal noise/sharpness for K5/Kit lens?
In reply to SenorBeef, Apr 23, 2012

I think the basc difference with a point-and-shoot is the much more selective focus.
If you do not like that you should not use a DSLR.

Maybe it helps if you select the central point and focus on that, but also that is a 'range' you cannot exactly control if there are several subjects in the center.

I see nothing surprisingly bad in your pictures, but if you feel uncomfortable with it you better try a different camera.

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