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Old Aug 18, 2007, 2:06 PM   #1
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OK, looking at the low end dSLRs (Cheaper) and researching them, I have a question about sharpness. I find I maybe getting to caught up on the sample pictures used on the review sites (Steve's is my fav.) and sharpness of the photos.
Reading things like "Need to step up the color and the sharpness" or "Default sharpness is soft" and even "Better to step up the sharpness +1".

So does that mean the camera doesn't take that sharp of a picture and needs to utilize software sharping? I would guess many things can cause that, but I read decent things about the "kit" lenses, then a paragraph later say need to step the sharpness up. So what does that really mean?


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Old Aug 18, 2007, 2:29 PM   #2
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Some cameras (not just DSLRs) use less in-camera sharpening as the default than others. If a reviewer indicates that you should use increased sharpness or saturation or contrast, remember, that is his opinion. The information is not to be taken as anything wrong, just that the maker was using a different way of looking at things. Mostly a matter of taste. In some cases, the intent is to create an image which is more like what you would get from a film camera.

If you really look at the default pictures from a number of different cameras, you will find the manufacturers have different views of things like tonal curves, sharpness, noise reduction, contrast, and detail. I tend to prefer the camera give me more neutral settings so I can make the changes I feel necessary for each individual image. Many people want the high-contrast, smooth, warm look that the popular cameras seem to provide.

Bottom line; is the default setting what you want? If not, can you get it that way? Are the other features of the camera important enough for you to make the changes?

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Old Aug 18, 2007, 7:53 PM   #3
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I agree with VT - the defaults for dSLRs are set "low". The reason seems to be that stepping up the sharpness, contrast, saturation, ... to the levels that most folks like causes irreversible changes. That means if you decide it needs less saturation, you will loose more quality than deciding later to increase the saturation.

Experiment. Figure out what works for you. What works when using flash. What works for skin tones. ... If you find yourself always wanting to step up the sharpness with your editor, you want to step up the sharpness setting in the camera.
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Old Aug 18, 2007, 9:14 PM   #4
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Sharpness is mostly a function of the lens, not the camera. Lack of sharpness can result from subject or camera movement as well as the quality of the glass you're shooting through. The camera must make the lens focus properly (if autofusing)... that's the main effect of the camera in the sharp image equation. You need great light for great pictures.

Spend your money on good glass... it'll outlive several camera bodies.
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Old Aug 19, 2007, 9:54 AM   #5
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Wildman wrote:
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Sharpness is mostly a function of the lens, not the camera. Lack of sharpness can result from subject or camera movement as well as the quality of the glass you're shooting through. The camera must make the lens focus properly (if autofusing)... that's the main effect of the camera in the sharp image equation. You need great light for great pictures.

Spend your money on good glass... it'll outlive several camera bodies.
I agree, but have a bit of a quibble: with digital cameras sharpness is a function of both the lens and camera - though the kind of sharpness the camera controls should really be called local contrast while the lens sharpness could be refered to as resolution. Howerver those terms are assigned there will be confussion, so they may just as well left as they are.

I also agree that good glass is good to have, though I have never had the money to buy really good stuff at US$2,000-5,000 each. One thing to keep in mind is that the kit lens for most (all?) dSLRs are not the best, but are very good value for the money. Another thing to remember is that pretty much all lenses are good (perhaps not great) when shut down a couple of stops.

So if you buy cheap/moderate priced glass, don't think it is going to be real good wide open, .e.g., that US$100 long zoom might be usable only in bright daylight - perhaps even then only with a bump in ISO. But if your main use is shooting daylight kids' games for small prints or the web, that could be a very usefull lens to have. Don't even think about night football with cheap glass - you could try it and might have something like1 in 100 shots work well.

The shots below were taken with an US$80 used 100-300mm zoom. Just fine at web resolution, but will not stand up to making a large print.

The basic problem is that a cheap lens must be stopped down to the point that you are not able to stop motion blur.

Though sometimes a bit of motion blur is not altogether bad.
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Old Aug 19, 2007, 12:26 PM   #6
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There are two distinctly different kinds of sharpness in digital imaging.

One type is the resolution of your lens/sensor/processor combination. A good lens on a full sized 16Mp sensor on a Canon EOS-1Ds Mark II is going to give more detail than the same lens on an APS sized sensor of lower resolution. So if you took a football team photo and made a 20 X 30 inch print you could make out the individual faces better with the higher resolution. In that sense the photo is sharper.

The other type of sharpness is an optical illusion of sharpness created by software or firmware. Edges are accentuated with a halo. This halo if properly done isn't apparent looking at the image but you can see it if you blow it up. It doesn't improve detail at all, but gives the overall impression of sharpness viewed at normal size. Most digital images look better with some of this type of sharpening.

This is an example I found online. Without any sharpening the edge between the two levels of gray would be a sharp line. This is a blow-up of what sharpening does to that edge:



It doesn't look sharper in the blow up – a straight edge would look much sharper. But viewed at normal size your eye sees the edge as being sharper.

The comments you are reading feel that this optical illusion should be set stronger. That has nothing to do with your lens/camera resolution.

If you don't post process and like the images directly from the camera to look good you can set the sharpening, contrast and saturation to your liking. If you post process it is better to put them all on their lowest settings or bypass the camera alterations by using raw.



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Old Aug 20, 2007, 10:48 PM   #7
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Well see, not being able afford those large sensor cameras and being limited to say used *ist or maybe a K100D, I thought I could spend more on some older prime lenses and get better pictures (as an example, not sold on those cameras). Because yes via software you can improve what the sharpness really looks like, but you can't improve it really over what the camera took. But that leads me back to how sharp is sharp? Do some cameras actually soften the sharpness knowing it is not reversable? Is a optically true 6MP sensor equally sharp in any brand camera? Can the only way to get a truly sharp (untouched) image is shooting raw?
I guess "going digital" just changed the dark room to a computer s all. :shock:
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Old Aug 21, 2007, 2:44 AM   #8
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No, cameras don't, "soften the sharpness", I'm not even sure I understand what you mean by this.

I think somewhere along the line you may have become a bit confused about a few things. Let me see if I can make it clearer.

A 6 megapixel camera has a sensor with 6 million photosites, each gathering light. The thing is, on most sensors each photosite only gathers light from one color band, either red, blue or green. Half the photosites do green, a quarter red and a quarter blue.

Because you obviously don't want an image composed of red, blue and green dots, the camera basically creates pixels in between each set of 4 pixels, averaging out the 4 colors. Because of this, a 6 megapixel camera isn't technically capturing 6 million pixels of complete color data, it's more like 1.5 million pixels interpolated into a 6 megapixel image (that's a bit over-simplistic, but close enough to get the idea).

Therefore, when an image is viewed at 100%, meaning at a 1:1 ratio of image pixel size to monitor pixel size, it will appear a bit soft. By applying a sharpening filter, the camera or software can create the illusion of a sharper, more detailed image.

Here's a photo I took which I'll use to illustrate what happens. I shot this with the K100D using the kit lens in RAW mode.






I've made two versions of this image, one without any sharpening applied, and one with a rather high level of sharpening. Here's a crop at 100% with no sharpening:






Here it is with a rather high level of sharpening:






The first image is pretty much what the shot would have looked like if I had taken it as a JPG with no sharpening. The second is what the shot probably would look like as a JPG with a high sharpness setting, OR if I had applied sharpening later on to the first image.

So you can really see what's happening, here's a very closeup shot of the first image with no sharpening:






And here it is with high sharpening:






As you can see, while the sharpen filter made the image appear more detailed and sharper when viewed at a lower zoom level, once you get really close you can see that it doesn't have more detail at all. You can probably also understand why there would be a problem trying to work with the oversharpened image, particularly if you wanted to enlarge it. You could always enlarge the first image and apply sharpening later, but there isn't a lot you could do with the second one except use it as is.


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Old Aug 21, 2007, 2:45 AM   #9
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fofa,

You seem to have hold of the wrong end of the stick in a number of ways.

A good place to start is here:

http://www.luminous-landscape.com/tu...harpness.shtml


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Old Aug 21, 2007, 3:14 AM   #10
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Quote:
But that leads me back to how sharp is sharp? Do some cameras actually soften the sharpness knowing it is not reversable?
All DSLR cameras give you a choice of how much artificial sharpening you want to add to the image. Unfortunately many don't give a completely unsharpened image at the lowest setting. It is an advantage if you can turn the sharpening completely off as that is the best image to post process. Sharpening should be done last so you aren't accentuating the sharpening halos. That is one of the reasons people shoot raw.

If you don't post process you want some sharpening. Digital images look dull and don't print well without some sharpening. Just set what you find pleasing. Keep in mind that an image sharpened properly for printing often looks oversharpened onscreen. It is immaterial whether people think the default sharpening is insufficient as long as you can set something you prefer. And yes some cameras have a lower default sharpening than others, which I think was your question.

Quote:
Is a optically true 6MP sensor equally sharp in any brand camera?
Tough question. At lower ISO you would be hard pressed to see any difference if you are referring to APS sized DSLR sensors. Differences in lenses and processing if you are taking JPG would probably overshadow any small resolution difference. Noise does reduce resolution and if one sensor handles high ISO with lower noise it could have a little better resolution. Of course in non-DSLR cameras there can be a big difference.

Quote:
Can the only way to get a truly sharp (untouched) image is shooting raw?
I would think so. All JPGs have some compression artifacts and TIFF is an impractical format IMO. Some cameras have sharpening artifacts at the lowest setting which would show up in both JPG and TIFF. Also JPG and TIFF images have color space, contrast and saturation. Contrast reduces your dynamic range and there is no way to get it back in PP. On the lowest settings and highest JPG quality all of those things are minimal, but you have to PP to get them looking good and you might as well start with raw.



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