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Old Aug 28, 2020, 6:33 AM   #1
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Default Why a resized photo is no use in showing camera quality?

We get many people here interested in camera/lens/image quality.... aren't we all really as this helps us to get a good image.

To be able to show this quality it can't be done by taking a full image and just resizing for the web as this will hide a myriad of issues including sharpness and noise. It is not until you see a 100% crop can this level of detail be determined. Now I'm not saying a photo must be perfect at 100% as unless you are printing very large it won't be seen, but I just want us to allow other members and guests to get a real idea of what they can expect. All too often we see someone say xyz camera is great, look at this sample, but it is just a reduced shot which tell nothing at all.

To be able to see what I mean I've used a photo which was taken by a friend of mine (we did a swap, I got her son for a minute and she got a Canon 5D.... I was happy to get the 5D back lol). The camera selected the wall behind us to rather than our faces however in the photo reduced for the web this is very hard to tell for sure.usps tracking showbox speed test

It is not until we see a 100% crop in the 2nd photo that it is possible to tell how far out of focus the faces are. So we go from thinking this has produced an OK but necessarily great photo to it being pretty soft when we see the real deal and probably not the sort of result we would want.

I'm not saying don't post photos at web sizes, as for a lot of things like composition, lighting and many other techniques they are great, as well as sharing some of the simply stunning photographs our members produce. It's only if you are trying to show the quality, please remember to post a 100% crop to let people know the real story (it's always worth showing the reduced and the crop shots the same as I have here so we know what we are looking at).

Last edited by AmirJustin; Aug 29, 2020 at 1:49 PM.
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Old Aug 28, 2020, 11:01 AM   #2
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A 100% crop is no use in showing camera quality either.

A 100% crop of a 12MP image may show a single errant pixel, while a 100% crop from a 24MP image may show 2 or more. From that, one might conclude that the 12MP image has less image noise, but that would be incorrect. What that wouldn't show is that greater resolution means that individual errant pixels have less impact on image quality as a whole, because individual pixels compose a smaller portion of the total image. So resolution hides noise and increases image quality.

But to reinforce the point you're making, downsampling (as in reducing the resolution for display) AND upsampling (as in increasing the resolution for printing) both will naturally average out imperfections.

I had two 8x10 photos hanging in my dining room, both of my wife riding in equestrian competitions. One was taken by a professional photographer using a Canon film SLR, and the other by me using a 3MP Nikon 880 P&S, and cropped to about 2MP. You needed an eye loupe to tell which was which.

So any serious attempt at comparison is futile, especially when trying to present the comparison through a computer screen.
  • The lens is the thing.
  • 'Full Frame' is the new 'Medium Format'.
  • "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.

Last edited by TCav; Aug 28, 2020 at 11:03 AM.
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