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Old Jul 31, 2010, 4:32 PM   #11
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Well,
I still have to read a bit here, but for reference here are comparison shots with f/3.5 and f/22, taken with the kit lens at 18mm. I took the right half image from the f/22 shot and pasted it as a layer over the f/3.5 image. After flattening layers I only adjusted the histogram, so no postprocessing magic.

This is quite a difference in my eyes. And yes, it's an extreme example, but I wanted to show what bothers me.

Of course the vignetting effect lessens the more you stay away from the wide open setting.

Now the good news - I used the kit lens today and had it at high and very high apertures almost all the time - quite a change from my usual settings. From what I've seen so far the vignetting effects are way lower, so thanks again for reminding me to stop down a lot in wide shots.

Regards,
Th.
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Old Jul 31, 2010, 9:14 PM   #12
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That is an interesting composite that you produced - great analysis. I tend to use the reviews like ...
... to determine the apertures where the lens is sharpest. For the kit, its f8 @ 18mm and f11 @ 45-55mm. At those apertures its well off of wide open, that you really do not have to worry about vignetting. So in the end I would think f8-11 would be more than sufficient to get a sharp image with good IQ, no vignetting, with out a whole lot of worrying.

In reading the photozone vignetting analysis, they attribute the problem to the front lens element not being sufficiently large. This goes to the heart of the wide angle and (for the crop sensors) ultra wide angle lenses, with the really wide and large front lens element. Coupled with high quality glass, and now you have expensive lenses.

At larger apertures, you need to start worrying about diffusion in the image. Diffusion essentially starts to balloon (or soften) the individual pixels, thus removing the sharpness due to how the light travels through the aperture and hits the sensor.

So bottom line, photography is all about compromise - take something too far in order to correct one aspect, and something rises up to bite you. Somewhat similar to "whack a mole".


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Old Aug 3, 2010, 5:55 PM   #13
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Hey,
I just wanted to say thanks for all the good hints and reminders and stuff. I played around with some of the last images and these were the results (panorama creation, crop, color/histogram works, denoise, resize) I've got from the JPEG's. RAW might give some improvement, but it's late already so I went the lazy route and took the JPEG's. I used the kit lens here.

#1 - evening scenery, 3 shots, 18mm, f13 - horizontal pano made from portrait shots
#2 - returning from the beach, 4 shots, 18mm, f11 - vertical pano made from landscape shots
#3 - with the sea in the back, 360, 11 shots, 18mm, f16 - horizontal pano made from portrait shots

So far I had no real vignetting trouble, I still have to check the pano's with more than one row/column, but that has to wait. Images look clear/clean to me without "shadows" or other vignetting artefacts, so I'm quite happy at the moment.

As for the crop - this is just the "technical crop" giving the maximum image after stitching without black borders. I am still unsure about the crop works for #1 and #2 (especially #2 to be honest). Any ideas/comments on that? Also... how do you like the 360 pano... normally it would show the land to the left and right, but this time I centered it in the image which gives kind of a "island" effect.

Anyway, thanks again for the help,
Th.
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Old Aug 5, 2010, 12:03 AM   #14
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I like all 3 of the shots. As you are finding out, there are other solutions to just having to go out and pick up additional equipment. Stitching is a wonderful alternative. Also, even with wide angle lenses, I still stitch, in that with the wide angle lenses in the vertical or portrait orientation, it tend to provide a taller shot.

There are also some scenes - like your beach, that you tend to stitch a lot of images together. However, you can also take a subset and just stitch 2 or 3 together, to form a smaller "close up". In this way you can make several separate images, in addition to the long panorama.

Try the evening sky just at sunset, when it starts to turn an iridescent blue - in the direction of the sunset. Also, do not trust your eyes. Take a couple of test images, as the blue looks better to the lens than to your eye, in a number of instances.

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