Posting here, I do 2 things that seem to improve the sharpness of the images.
(1) I post small pictures. H500 x W470 pixels or smaller seem to fit on the "preview" version of the posting here. As noted in old forums, the "original" version is not really working as a way to view pictures, so I figure "preview" is our primary venue. As Java has pointed out, the site seems to cook larger originals down for the preview version, and that process seems to make the preview versions blurry.
(2) When shrinking a picture (in general, not just for this site), I try to maintan the borders between pixels, so that borders between pixels on the resulting picture align with borders that were in the original. This means that I try to use "even number" shrinkage proportions of 50% (4 pixels become 1), 25% (16 pixels become 1), 20% (25 pixels become one), or 10% (100 pixels become one). I'm using MS paint to do this (I still don't have photoshop), which only allows whole number percents. I get 12.5% (64 pixels become 1) by shrinking 25% then 50%. Probably 40% (25 pixels become 4) is not so bad for sharpness. My feeling is that 30% (100 pixels become 9) should be avoided, because the original and resulting pixels will align only every 9 pixels. If you choose 33% (10,000 pixels become 1089, just off from 9 to 1) the pixels may align never or only in one location in a 500 x 470 picture.
When I have failed to follow this second guideline, the individual pixels seem to go in and out of focus in waves, as the borders between the original and resulting picture go in and out of alignment. Has anyone else noticed this?
For the same reason, I avoid rotating the picture odd amounts (e.g. 5 degrees to level a horizon). I only rotate in increments of 90%.
Having said that, sometimes the framing of the shot won't allow both even-number shrinkage and a size of H500 x W470, and you have to balance sharpness with composition.
As for this site, I guess if one wanted to post larger originals, posting picture sizes that are some multiple of 500 x 470 might yield sharp preview versions. I have not tried that.
Enjoy!
-Art-
CombineZM
I just wanted to let y'all know about some nifty free software for combining pictures. If you take several pictures with the same frame, but with different focal distances (and therefore different parts of the picture in focus), this software will combine the pictures and use from each one the parts that are in focus.
Here are the limitations I have found:
(1) you have to be able to manually focus your camera.
(2) to combine large numbers of pictures, you may need a faster computer. Combining 13 pictures takes about 1 hour on my 3 yr old hp. On the other hand, combining 2 pictures does not seem to take that long.
(3) the results seem better if your depth of field (part that is in focus) is already pretty deep. It's helpful if you can control your f stop. I've used f11 with good results.
Here's the link to the software:
http://hadleyweb.pwp.blueyonder.co.uk/CZM/News.htm