There is a difference between sharpness and resolution in a digital image.
I see too many Internet photo forum conversations by wannabe experts that confuse people on this issue. So my mission today is to get a bit more technical than usual and explain that sharpness and resolution are in no way related.
Now if I get too technical, don’t worry about it. Just ignore the basis of my argument and accept the concept that you can have a 14 megapixel sensor that doesn’t produce images that are as SHARP as a camera with a six megapixel sensor. In other words, sharpness and resolution have ABSOLUTELY NOTHING TO DO WITH EACH OTHER!
Here’s why. Resolution is not the number you see from the camera manufacturer. It doesn’t matter if you have an eight megapixel camera or an 11 megapixel camera. The true mark of your particular camera’s resolution is how many horizontal line pairs it can resolve given a certain lens mounted to the body. Resolving power comes from measuring the PICTURE pixels on your camera (not the same as the total number of pixels) for their ability to resolve data line pairs – per image height (and width). I know I may have lost you there. Your mind turned to mush. It’s based on linear algebra folks and it sucks. But trust me, it’s accurate.
There are additional measures of camera resolution; picture pixels and recorded pixels. Again – these measurements may have nothing to do with the total size of your camera’s sensor.
The second part of today’s post has to do with sharpness. This will really blow your mind. You can have a brand new Nikon D3 ($5000) with its massive sensor, and it may not be as SHARP as a Canon 40D with a smaller sensor. Why?
Because there are several variables that impact sharpness and have NOTHING to do with resolution. If you put a cheap, consumer lens on the Nikon and an expensive, pro lens on the Canon, it may outperform the Nikon. (By the way – the reverse is true. I could have come up with an example switching Nikon and Canon around. It doesn’t matter which brand you use.) Likewise, things like image processing, anti-aliasing filters and a host of other technologies that get in between the image and the sensor will cause differing degrees of sharpness.
So I hope you see the lesson here. The “My megapixels are better than your megapixels” discussions I see floating around on the photo boards are utterly stupid.
Don’t think you need that next 200 megapixel camera to get a sharp picture. You do not.
NOTE: I can’t devote enough time or space to turn this into a white paper, so invariably, someone will chime in with “You forgot to mention…” Please recognize I didn’t necessarily forget anything – I just may have decided not to include every technical detail for clarity or brevity’s sake.
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