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Old Jan 3, 2011, 11:01 AM   #21
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Thank you simple!
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Old Jan 3, 2011, 2:08 PM   #22
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...but I do have another.. How do you know what aperture you want to use. Is it by trial and error or is it experience? Is there some scale you use depending on the light available that you have memorized or have on a card? Do you take multiple pictures using varied settings on the aperture keeping the best one out of the set? How do you know?

O.K. Frank - now it's your turn! I needed some time to answer your question: How do I know which aperture to use?

_____xxxXxxx_____

First of all, 95% of my pictures are landscapes so, naturally I am mostly concerned about DOF in my pictures. The way to get greater (large enough) DOF is to use small apertures (small aperture-openings = big numbers). The smaller the aperture the larger the DOF - theoretical, up to a certain point - where diffraction (not so good!) kicks inn. Most lenses do have a point where smaller apertures than, let's say f:16 tend to produce Diffraction. Each lens is different concerning diffraction, so you have to read tests.

Read about diffraction:
http://en.wikipedia.org/wiki/Diffraction
http://www.imatest.com/docs/sharpness.html


My 'Use-It-For-95%-Lens' (Nikkor 16-85mm ED VR - http://www.photozone.de/nikon--nikko...3556vr?start=1 ) is at its "best" from around f/5,6 up to about f/16 where it has acceptable levels of vignetting, good resolution (or sharpness as we sometimes call it...) throughout and acceptable Chromatic aberrations values (CA) which are ususally more pronounced at wide settings anyway - AND is not yet affected by diffraction.

I try to use between f/5.6 and f/8 - f/11 and see what exposuretimes this gives me (keeping in mind that I sometimes need to compensate upp to 2-3EV's). Obviously, if the sun is bright I need to go up to lets say, 16 and higher, accepting low levels of diffraction, which I can somehow rectify by PP-sharpening.

If I use the lens all the way up to its 85mm-limit (short-tele), I need at least another stop on top of it's lower limit of f/5.6 to avoid loosing much of its border-sharpness.

Using f/5.6 I need to be special careful of where to set my focus if there is a lot of forground (like gras, trees og bushes). Anyway, to check my DOF I have a special button on my D300s which is my depth of field preview which I can use to check my DOF before I shoot. With f/8 - f/9 and gradually higher numbers (smaller openings) f/11 or f/16 it is easier, specially on the lower end of the focal-lenght, around 16-35mm.

All this with ordinary shots in daylight. With night-shots it is different alltogether, where ISO may play a part of the equation as well - if moving objects are part of the scene - something I try not to include, as choosing the right compromise between aperture and shutter-speed AND ISO can give you gray hair (my hair is already gray, so I don't care...!). Then there is the odd situation where I definitely WANT blurring to occure, like in my other thread: http://forums.steves-digicams.com/hdr/181307-november-rapids-after-long-spell-rain.html whereI wanted the moving water to show movement-blurring. In these cases I force the lens to use the smalles possible aperture (highest number) to be able to use slow shutter-speeds and lowest possible ISO-setting. What I really need is some ND-filters to bring my exposure-values down, so I wouldn't have to use f/25 (suicide !!) but good-on's are too expensive for me right now.

I hope this will give you some idea of how I decide on apertures. All of this is my own personal way of dealing with this issue, while other photographers may have a completely different approach to it.

I think - One needs to know one's lens, and how it behaves in certain conditions, to be able to get the best out of it. Reading some good tests and noting down / remembering the socalled "sweet-spots" and behaviours of good and detrimental characteristics of the lens, is one of them.


Best regards,
Walter_S

Last edited by Walter_S; Jan 6, 2011 at 8:24 AM.
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Old Jan 3, 2011, 2:34 PM   #23
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these look great walter. a blue/grey winter day is a tough image to capture. but in these you managed to keep the depth and the cold feeling of winter. while i like them both, i slightly prefer the first one, as the path through the trees gives a nice place for the eye to travel and adds a feeling of depth.

the slight halo around the trees almost bothers me, but not really enough to matter.
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Old Jan 3, 2011, 5:10 PM   #24
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Thanks, Dustin - appreciate your comments!

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Best regards,
Walter



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Old Jan 5, 2011, 4:53 PM   #25
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Thumbs up In regards to your answer Walter

Walter, Thanks for that explanation. I had no idea that it would be so in depth. The theoretical physics are a bit deep but understandable. Is this what goes through your mind when you are taking a picture? It kind of reminds me of over thinking a golf swing while addressing the ball. I guess at first, it seems more than overwhelming, but in effect when applied with understanding, and practice, it should be easier. I am still digesting the refraction formulas......I would almost surmise that you are a retired physics professor, or maybe even a current one. It is so gracious for you to have given me an answer with this "depth of field" . I can now see why it could not be given inbetween dinner conversation! ... ............Frank
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Old Jan 6, 2011, 9:01 AM   #26
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Hi, Walter. Thank you for the explanation. As usual your tidbits of information are small steps to take but make for giant leaps of exploration, to rephrase an oft-used cliche.

I would also like to add something surprising I found in the latest User Manual for Dynamic Photo HDR Version 5. It's about using JPEG instead of RAW for HDR-shooting:

"Most of the users should use multiple JPG files instead of multiple RAW files for the best HDR and Fusion quality." (p. 86, "Using RAW Files")

The justification is that camera makers spend a ton of money developing in-camera RAW-to-JPEG conversion software (among other software-based functionalities) best-suited for their hardware (lens, etc.). As a result, in-camera JPEGs are tailored to specific camera makes and are better quality than JPEGs created by any third party conversion software. The manual goes on to say that you are practically throwing away more than half of what you paid for the camera if you shoot in RAW.

In my case, I need to shoot in RAW because of fringing. My Sony A350's JPEG setting does not eliminate fringing especially on wide angle settings (~18mm). And I can only successfully eliminate fringing using Photoshop CS3's Adobe Camera RAW program which works on RAW. Photoshop editor's "Chromatic Aberration" (under Filter->Distort->Lens Correction) does not do as good a job.

So I'm just hoping that Photoshop CS3's Adobe Camera Raw's JPEG conversion (being part of an expensive software suite and not of some free editor that came on the camera's CD) is also as good as my A350's in-camera JPEG conversion, so I don't sacrifice quality for de-fringing.

In any case, if DPHDR5 is right, you may be better off staying shooting in JPEGs.

Great shots, BTW. When you posted them I was wondering, did you try CS3's Auto-Level in combination with Auto-Color? Sometimes, in my mostly B&W winterscapes (my Scotchtown Countryside shots in another thread, in particular), I used them to make the colors look more natural.
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Old Jan 7, 2011, 9:56 AM   #27
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"Most of the users should use multiple JPG files instead of multiple RAW files for the best HDR and Fusion quality." (p. 86, "Using RAW Files")

....I was wondering, did you try CS3's Auto-Level in combination with Auto-Color? Sometimes, in my mostly B&W winterscapes (my Scotchtown Countryside shots in another thread, in particular), I used them to make the colors look more natural.





Thanks vvcarpio, for your much appreciated words of wisdom - I think I will use you as my alibi from now on, when people start nagging for me to shoot RAW!

That info on Auto-Level and Auto-Color in CS3 is interesting - must try! Until now, I never used anything labeled "Auto" in PS / Elements, because I am a control-freak and want to be in charge myself. But since you brought that situation up, I will have a go - Thanks for the tip, vvcarpio!

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