Hi,
To get really long depth-of-field (and/or force a longer exposure), do you use apertures narrower than f/8-f/11? In my attempts I found that IQ drops noticeably if I go that narrow. I use XTi/40D and I've experimented with a few of my lenses...
Tony
Bryan (the author here) has started to publish data regarding the Diffraction-Limiting Aperture of various Canon bodies. For the XTi/40D (i.e. 10MP at 1.6x crop; it's all about the pixel spacing so the body model doesn't matter) the DLA is reported as f/9.3. I haven't seen much impact with DLA, but I'm not a pixel-peeper either (usually).
We're a Canon/Profoto family: five cameras, sixteen lenses, fifteen Profoto lights, too many modifiers.
Of course I stop down! What else would I do? Not take the photo? I don't know the meaning of them horrible words.
If the shot calls out for deeper DOF, I stop down. It doesn't matter if it's f/11, f/16, f/22, or f/32. I'm going to do what it takes to get the shot. (Of course, it would be far better if I could use focus stacking or some other technique to get the shot without diffraction, but many times that's impossible.) You can get back some of the resolution lost to diffraction through sharpening if the image has very little noise.
Diffraction is a fact of life. A picture that has visible diffraction is better than no picture at all.
It's the same way with noise. If a shot calls out for underexposure (high ISO), I underexpose. It doesn't matter if it's ISO 1600 or 56,000; I'm going to do what it takes to get the shot. Of course, it would be better if I could use image stacking, flash, or some other technique to get the shot without underexposure, but many times that's impossible. You can get back some of the image lost to noise through noise reduction software (desaturation, etc.).
Noise is a fact of life. A picture that has visible noise is better than no picture at all.
Personally, I use a wider aperture as you mention. Some advice I picked up somewhere was that the close objects can be a little out of focus, because they are big and you don't notice it as much. The objects further away need to be sharp to make out the intricate detail. Of course this is talking landscapes with say, a log, as the foreground object of interest, but the background is what you are really looking for.
Tom
Rarely. When I shot film, I used f/16 frequently, but that was before the days of dust on sensors and DLA. (It was also before the days of change-on-the-fly ISO--we're talking film here--and sometimes the camera would be loaded with higher ASA* film than the situation called for...again, in the days before shutter speeds went above 1/1000th*).
Today, with other ways to control light, it's a rare situation when I have to use narrow apertures--only when I want to make an image that calls for thatmuch DOF. Usually selecting f/8 - f/11 and using a wide-angle lens give me all I need.
* Man, am I dating myself here or what? (Saying "man" probably does that too...guess i should be saying "dude" or "bro"?)
<span style="font-size: 6pt; color: black; font-family: 'Verdana','sans-serif';"]
<span style="color: black; font-family: 'Arial','sans-serif';"]<span style="font-size: small;"]To get the max Depth of Field (DOF) you need to use a wider angle lensat the proper shooting distance. There are DOF calculators that can help. Using apertures larger than f11 usually start to soften the image.<o></o
<span style="color: black; font-family: 'Arial','sans-serif';"]<span style="font-size: small;"]Try this URL to use the DOF calculator.<o
<span style="color: black; font-family: 'Arial','sans-serif';"]http://www.cambridgeincolour.com/tutorials/DOF-calculator.htm<o
<span style="color: black; font-family: 'Arial','sans-serif';"]<span style="font-size: small;"]Bob<o
There are apertures narrower than f/8? Who would have known. Honestly, I spend all my time at f/2.8-f4.0 because I like really shallow depth of field, which also explains why I toss so many pictures because only one of the brides eyes are in focus.
I don't think I've ever been above f/8.0, at least that I can remember.
I uses 2,8 to 8 depending on light situation but F8 is sharpest
Originally Posted by Tony Printezis
Tony,
I have used my XTi with F16 for a good number of times and I barely found any image degression. I will use F11 or narrower to get great DOF or I need to push for long time exposure. If you're shooting night scenes with long time exposure, first make sure that your camera is supported steadily and you use a remote controller or cable release. I found myself not getting sharp enough shots because of slight camera shaking (some time it'sdue tothe wind). The diffraction (regarding XTi at least) should not be a concern at F16 in my opinion.
Ben
I rarely go above f/13. It depends on the camera, of course, and the sensor pixel size.
I did take a number of f/22 shots a while back, and I was disappointed in their IQ. Since then, I've stuck with f/8 or wider, and an occasional f/11-13.
Film? That's a different story. F/16-22 will give sharp images with a deep DOF, but not a digital camera. Not yet, at least.
Because of digital, go ahead and take the shot anyway.
I wish I had taken those f/22s at f/8, too, but I didn't. So, I got what I got.
I'd rather have a better image quality, then a lousy one with a great depth of field.
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