Sheri, I like this photo... nice pose and love that reflection. Thanks for your comments; I am still surprised by this site - that people upload photos and never bother to comment on others'. I feel like I am getting to know about 6 good members.
Thank you all!! I can feel light bulbs going off in my brain...things I've begun to question are now clarified and totally makes sense. Thank you for explaining things so clearly. You all have been very helpful!
I can't explain the reasons for the diffraction and loss of sharpness at smaller f/stops....it is beyond my technical understanding and expertise. I just know that years ago, I had a problem with sharpness and someone who was more knowledgeable than I told me about it, and I noticed the difference right away when I didn't stop down quite as much, and paid more attention to my actual 1/3 focus point. I think it is even more of a factor in macro photography, which is why some people are using a technique known as 'stacked photos', where multiple images are taken at slightly different focus depths, but using a more open f/stop to maximize the sharpness and combined using a computer program. The results, if one knows what one is doing, are incredible.
Sheri: check out the two most recent photos I've posted for some examples.
I think this is very helpful for everyone, thanks Allen. I do use circular polarizers very often and ND for waterfalls sometimes. I understand what you mean about the 41 mm focal length on a crop sensor camera (mine has a cropped sensor) but I still have a hard time wrapping my head around the argument of a lens getting softer because of diffraction as you stop it down to f22 versus being sharper at f16 but less depth of field.
I agree with trying a wider angle and larger f/stop, and then cropping out the out-of-focus portions (if you can't move closer), if they are too distracting. As a comparison, many P&S cameras have such a wide angle that they can get the entire image in reasonable focus at f/5.6 or wider and the difference is primarily because they have such a wide angle. Most P&S cameras don't go any smaller than f/8, and they don't need to. In Sheri's image, I see that the focal length is 41 mm which on a crop sensor of the T2i is the equivalent of 65.6 mm focal length on a full frame camera, and is the equivalent of a very short telephoto. In general, the wider the angle, the more of the image is in focus. If Sheri had been able to set her lens at 24 mm (equivalent to 38 mm) or wider and moved in proportionally closer, I expect the majority of the image would be in focus even at f/11.
I have used f/18 to f/25 in some cases, most often in macro work, and while the depth at f/25 is useful, it isn't quite as sharp as f/18 or larger. For waterfall or sunrise/sunset shots, to get a silky smooth look of the water as a result of long exposures, I have used f/22 or smaller, but would prefer larger f/stops for overall sharpness. As a better alternative in those cases, I used to use a polarizing filter to cut the light out, and in more recent years, I resort to a neutral density filter to get the longer shutter speed. I also plan to go to such locations either on overcast conditions, or in the case of sunrise/sunset shots, before or after the sun has risen or set.
Sorry if there is too much repetition here, but it is an interesting situation.
Sheri, the other thing you can do in a shot like this is shoot with a slightly wider focal length, focus at the lighthouse (it is the subject you want in focus, right) and then if you shot at lets say f16, sure some of the foreground will be a bit out of focus but because you shot a bit wider, you can crop some of the foreground out later. Wayne or Allen, what do you think.
I don't mind cluttering up the comment section, especially when we can all learn. I have struggled for some time over the best f stop for lens sharpness versus stopping down for depth of field. I shoot mostly with an 18-200 multi purpose zoom which is not exactly renowned for sharpness. I don't hesitate to stop down to f18 and used to use f22 for waterfall shots all the time. Attached photo is at f18 and given the lens I use I don't see how you could complain about depth of field or sharpness.
Sheri, I think in your example, the camera is autofocussing on the wrong spot, too much in the foreground. If you try what Allen suggested, manually focus one third of the way into the scene, that should give you the best overall sharpness. Then, to check this lens diffraction softness issue, I would manually focus one third of the way into the shot, then shoot a series of photos from f8 to f22 and that will prove to you how far you can go before the photos get softer due to that effect.
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A beautiful pastel floral.. great bokeh, too!
Sheri, I like this photo... nice pose and love that reflection. Thanks for your comments; I am still surprised by this site - that people upload photos and never bother to comment on others'. I feel like I am getting to know about 6 good members.
Thank you all!! I can feel light bulbs going off in my brain...things I've begun to question are now clarified and totally makes sense. Thank you for explaining things so clearly. You all have been very helpful!
I can't explain the reasons for the diffraction and loss of sharpness at smaller f/stops....it is beyond my technical understanding and expertise. I just know that years ago, I had a problem with sharpness and someone who was more knowledgeable than I told me about it, and I noticed the difference right away when I didn't stop down quite as much, and paid more attention to my actual 1/3 focus point. I think it is even more of a factor in macro photography, which is why some people are using a technique known as 'stacked photos', where multiple images are taken at slightly different focus depths, but using a more open f/stop to maximize the sharpness and combined using a computer program. The results, if one knows what one is doing, are incredible.
Sheri: check out the two most recent photos I've posted for some examples.
I think this is very helpful for everyone, thanks Allen. I do use circular polarizers very often and ND for waterfalls sometimes. I understand what you mean about the 41 mm focal length on a crop sensor camera (mine has a cropped sensor) but I still have a hard time wrapping my head around the argument of a lens getting softer because of diffraction as you stop it down to f22 versus being sharper at f16 but less depth of field.
Thanks Sheri and Allen.
I agree with trying a wider angle and larger f/stop, and then cropping out the out-of-focus portions (if you can't move closer), if they are too distracting. As a comparison, many P&S cameras have such a wide angle that they can get the entire image in reasonable focus at f/5.6 or wider and the difference is primarily because they have such a wide angle. Most P&S cameras don't go any smaller than f/8, and they don't need to. In Sheri's image, I see that the focal length is 41 mm which on a crop sensor of the T2i is the equivalent of 65.6 mm focal length on a full frame camera, and is the equivalent of a very short telephoto. In general, the wider the angle, the more of the image is in focus. If Sheri had been able to set her lens at 24 mm (equivalent to 38 mm) or wider and moved in proportionally closer, I expect the majority of the image would be in focus even at f/11.
I have used f/18 to f/25 in some cases, most often in macro work, and while the depth at f/25 is useful, it isn't quite as sharp as f/18 or larger. For waterfall or sunrise/sunset shots, to get a silky smooth look of the water as a result of long exposures, I have used f/22 or smaller, but would prefer larger f/stops for overall sharpness. As a better alternative in those cases, I used to use a polarizing filter to cut the light out, and in more recent years, I resort to a neutral density filter to get the longer shutter speed. I also plan to go to such locations either on overcast conditions, or in the case of sunrise/sunset shots, before or after the sun has risen or set.
Sorry if there is too much repetition here, but it is an interesting situation.
Thank you Larry. I will definitely try yours and Allen's advice, the next time I try a landscape. I'm writing all this down.
Sheri, the other thing you can do in a shot like this is shoot with a slightly wider focal length, focus at the lighthouse (it is the subject you want in focus, right) and then if you shot at lets say f16, sure some of the foreground will be a bit out of focus but because you shot a bit wider, you can crop some of the foreground out later. Wayne or Allen, what do you think.
I don't mind cluttering up the comment section, especially when we can all learn. I have struggled for some time over the best f stop for lens sharpness versus stopping down for depth of field. I shoot mostly with an 18-200 multi purpose zoom which is not exactly renowned for sharpness. I don't hesitate to stop down to f18 and used to use f22 for waterfall shots all the time. Attached photo is at f18 and given the lens I use I don't see how you could complain about depth of field or sharpness.
Sheri, I think in your example, the camera is autofocussing on the wrong spot, too much in the foreground. If you try what Allen suggested, manually focus one third of the way into the scene, that should give you the best overall sharpness. Then, to check this lens diffraction softness issue, I would manually focus one third of the way into the shot, then shoot a series of photos from f8 to f22 and that will prove to you how far you can go before the photos get softer due to that effect.
Wayne, I have emailed you...