Habitual Cropping - your worst enemy?

tonylong wrote in post #12998548
It's my old XP workstation. I have managed so far, simply because I have way too many things on my table for my budget, this has to sit in line, and at this point it is usable (and I also have my little laptop with Win7 64 that typically won't reboot on me) so for now this is just something I live with. But dang, I typed that little essay out on the fly with several thoughts floating around, and I just don't have the energy to re-think and re-type!

But, enough about me, onward with the discussion!

tony, of topic but I upgraded my computer by added a new hard drive. but rather than replace the old I left it. switched the sata to the new drive. Booted up. "No operating system" put in windows 7 DVD" now I had a brand new shiny computer kinda. Super clean, no prepackaged junk. reinstalled programs I needed.

When I needed my "old" computer I just switched the sata cord back.
interim i woulod load files to a "my book" shut down switch sata to new and transfer

When I was sure I had everything I needed I just stopped using the old drive
But it's a great way to keep your old and "new" computer going for 50 bucks or so

Roy_W wrote in post #12998836
Can you please explain from a technical point of view how a 100% crop can decrease IQ when you do not increase the scale of the cropped image. Personally I do not understand the logic.

Nope, I can't explain it and I don't understand it either; I just know what I have seen. Here are a few posts from another thread that show 100% crops and the full frame image. The noise is much more apparent on the 100% crop than it is on the reduced image. I can guess that most software that reduces an image will produce one red pixel when reducing 8 pixels: 7 red and one white noisy one,

The problem is more apparent at high ISOs.

https://photography-on-the.net …hp?p=9253826&po​stcount=70

https://photography-on-the.net …hp?p=9253107&po​stcount=64

https://photography-on-the.net …p?p=9309842&pos​tcount=130

Note that here I have picked sample that present the problem more clearly than some other posts in that thread. But also note that the thread is titled: "If you're happy with your Canon 7D images and 100% crops," meaning that it was not intended for shots where people were not happy with the 100% crops. The selections I have chosen are pretty representative of what I see when looking at my images at 100%

hairy_moth wrote in post #12999093
Nope, I can't explain it and I don't understand it either; I just know what I have seen. Here are a few posts from another thread that show 100% crops and the full frame image. The noise is much more apparent on the 100% crop than it is on the reduced image. I can guess that most software that reduces an image will produce one red pixel when reducing 8 pixels: 7 red and one white noisy one,

OK hairy Moth know I understand your statement. Please allow me to address everyone here. ( HM = HairyMoth )

When I see the quality of the images that HM speaks about I understand his previous statement. Obviously it would be very difficult to crop images with such a low IQ.

Below I will give you an example of the images that my 5D MKII produces. This photograph was taken with a 135Lmm 1/200 at f5.6 from about 1.2 metres.

This 1st image is the original scaled down from 5600*3700 ( 240 DPI)to 1200*800 (240Dpi).
I think you will agree that the quality is not too bad but that there is a lot of green. The 135mm was the only lens that I had that day.

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Well, there are various things that can affect a 100% crop and, of course noise from an image that can show up noticeably when either a High ISO was used or areas that have had the brightness boosted is one of those issues -- if, rather than enlarging the 100% crop to "full size" you reduce full image to post on the Web or you print at a size that doesn't "simulate" a 100% crop, then the noise will tend to be "drowned out" -- it's in the original image, but it doesn't look bad at all in the reduced image. It has less to do with whether you are starting with a full frame image or not -- the links you posted there were about the 7D, not a full-frame body. In fact, as a rule full-frame sensors tend to produce images with less noise-per-pixel, but that's another discussion.

But, to me the other most practical concern is simply that a closely cropped image has less usefulness when it comes to displaying/printing. I can take a 100% crop and print a nice 4x6 or 5x7 print from it, and since such prints are so undemanding, and because the resolution "needed" for decent quality is not far from the resolution of a 100% crop, then I'm not fussed about that. But, when you get to, say, an 8x10 print, then you start to notice thngs. Noise and softening of detail will become apparent with an 8x10. And that matters to me because an 8x10 is to me a "coffee table" size -- show to guests and they will pick it up and look in a way that will be at least as bad as you viewing the 100% crop on your monitor. So, if I look at a close crop on my monitor, if it looks bad at a 100% view, well, I have no use for that.

A few days ago I used my macro lens to chase some little flies around on my deck. They were so little that unless I got really close the shots would require a 100% crop to look like any kind of composition. I used a tripod, but still the skitterish critters kept flying away, so getting to the "full macro" closeness was, well, a pretty tough and frustrated exercise. So, did I get any "keepers"? Well yeah, although I've yet to process them for any kind of output. But, they all look best, like I said, as 100% crops, dang!

Also, I did some "Shooting the Moon" sessions for six early mornings last week, using my 100-400 lens with my 1.4x TC, so 560mm of "reach" mounted on my 1DM3 on a tripod, and using a cable release to minimize camera shake, all to maximize sharpness, and that knowing well that first, using a converter on a lens like that will not give the sharpest results, and second, knowing that even with 560mm of focal length, the moon will still be a "little ball" in the "big sky", and to come out with a "decent moon shop image", well, yes, I would need to crop "a lot"...

Well, here are a couple of those crops: