fjp,
Does anyone understand why I would get this results? It looks like
I should always be shooting with no internal sharpening, which is
what I thought I was doing all along. Although I've been using it
for years, I don't understand the theory behind USM to understand
the results I got. I understand that in using Auto I was sharpening
on top of sharpening.
You just discovered something that has been known to us intermediate and pro digital shooters for a long time.
It is always better to sharpen in post than in camera.
The reasons have to do with several factors, first of all if you read the section in the manual on how AUTO sharpening works you'll realize that it really works like a magic dial across the available settings, the camera decides based on the orientation and amount of detail which setting to apply, as you know that range:
auto, -2,-1,0,1,2 , none
so obviously in auto mode the camera has 6 possible options, (-2 to +2, none) but in my experience Nikon's algorithm for auto (it seems to work the same way on the coolpix cameras) almost never tends to choose the "none" option. In fact it more likely will choose a moderate to high sharpening setting (> 0) when this occurs first of all the camera has to think a bit harder to process the image (which means it might add a tiny bit to processing time when shooting continuous shot bursts) secondly the sharpening algorithms used in the camera are only so and so compared to the advanced options afforded by using USM in your favorite image editor. In those programs you can control the intensity, radius and threshhold of the applied sharpening. You can even mask off portions of the image for sharpening or just sharpen the edges and leave flat expanses of color alone. This is precisely how the pro's do it in post processing to produce the jaw dropping images you occasionally see posted. So all this capability is obviated by using auto in the camera, well you can still do it but now your image data has already been changed by the setting (unless you shoot RAW that is!) A third factor is the intelligence of the algorithm in auto mode, it's not very smart..it will blindly apply a "high" sharpening to a sun set shot with deep blues in the sky (which as you know will bring noise in the sky alive) it will similarly make bad decisions under indoor flash conditions and seems oblivious to how the noise generated by sharpening is exacerbated by highier ISO settings. This is what explains the irratic noise behavior that some people mention, "oh this shot came out noisy...I wonder why?"...quit shooting in auto mode and you essentially eliminate that inconsistency. To continue with ISO, sharpening will bring out the beast in high ISO images, if you plan on shooting high ISO
never sharpen your images in camera, you are already going to suffer from the increased noise due to the amplification required for the highier ISO level, no reason to make it even worse by applying a rough sharpening pass in camera to further degrade the image. I think the most important factor is processing power and fidelity, in photoshop you can work on high bit data (16 bit space) and in a high gamut (Adobe RGB should be your prefered color space in the body if post processing is going to be part of the image work flow!) while shooting RAW, doing USM on such an image allows you to use the horsepower of your pc and the more accurate sharpening algorithms of photoshop to optimize your image. The camera has to apply it's sharpening quickly to the image in camera, so it is very rough at best...USM in photoshop maximizes detail retention while minimizing generated noise, and in fact with masking restricts the sharpening only to the areas you wish as previously mentioned. Remember also that if you shoot jpeg, your settings are final ! whatever sharpening the camera does to the image is yours to keep..post processing can only work from what the jpeg provides (where as in NEF, the sharpening chosen in camera is only a "recommendation" associated with the image data and can be changed without changing that data) so if you plan on post processing jpeg images, it's best to shoot them as no sharpening otherwise you will have to undo the damage caused by using auto or another fixed setting, all of which will significantly increase the noise in the image you will be post processing.
For the best possible image, there is no better option then to shoot with sharpening off and then USM as a post process, this goes for RAW or JPEG.
I
always shoot with sharpening off in camera, even with a basic USM pass on the pc the results in photoshop out class the limited (but welcome) options available in camera, it gets better when the advanced methods (masking,edge restrictions..etc.) are used. Luckily the noise performance and quality of the D70 is outstanding to start, with an extremely tight grained monochromatic structure up to it's highiest ISO with minimal chromatic variance. This makes it particulary amenable to application of USM especially when used in conjunction with smart de noise tools. (if you want to completely obliterate it for high ISO long exposures say..)
Oddly, though, I have been very satisfied with the results I have
been getting shooting in the Auto setting. But apparently I could
have been getting even better results shooting with no internal
sharpening at all. I just don't understand why.
Hopefully you do now
Regards,
--
