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Nikon D70: Dark Circular Marks in Sky
Alfred Molon wrote:
In article 1122588119.285579@ftpsrv1, frederick says... The fact that the dust is visible, and that the image is not very sharp indicates to me that a very small aperture was used - as does the motion blur which tells me that a fast shutter speed was not used. Above about f11, sharpness will be lost on a dslr like the D70 At what aperture is the diffraction limit for a camera like the D70 ? Take a look. http://www.geocities.com/angels2000photos/diffract.jpg I think that you can see slight loss of acutance even at f11 - but not enough that you would even notice on a print - even a large one. By f16 it's pretty visible, by f22 it's very significant. Those are 1:1 crops, but I think loss of sharpness is going to be noticeable on anything but a very small print by the time you get to f16 of greater. http://www.geocities.com/angels2000photos/diffract.jpg Frederick Thanks for that info - I'm a pretty much a noob at this lark Do you have any links for further reading easily to hand TIA Tim http://www.timdenning.myby.co.uk/ |
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Nikon D70: Dark Circular Marks in Sky
Tim wrote:
Alfred Molon wrote: In article 1122588119.285579@ftpsrv1, frederick says... The fact that the dust is visible, and that the image is not very sharp indicates to me that a very small aperture was used - as does the motion blur which tells me that a fast shutter speed was not used. Above about f11, sharpness will be lost on a dslr like the D70 At what aperture is the diffraction limit for a camera like the D70 ? Take a look. http://www.geocities.com/angels2000photos/diffract.jpg I think that you can see slight loss of acutance even at f11 - but not enough that you would even notice on a print - even a large one. By f16 it's pretty visible, by f22 it's very significant. Those are 1:1 crops, but I think loss of sharpness is going to be noticeable on anything but a very small print by the time you get to f16 of greater. http://www.geocities.com/angels2000photos/diffract.jpg Frederick Thanks for that info - I'm a pretty much a noob at this lark Do you have any links for further reading easily to hand http://www.cambridgeincolour.com/tutorials.htm http://www.cambridgeincolour.com/tut...otography.htm# I think that is a good source of information - and particularly in explaining the effects of sensor format, aperture, focal length on DOF, taking into account diffraction, and most importantly the different parameters that apply for assessing sharpness on final prints - such as size of print and viewing distance. It also explains why trade-off between loss of acutance or resolution from diffraction may be acceptable when extra depth of field is desired. |
#3
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Nikon D70: Dark Circular Marks in Sky
Tim wrote:
Alfred Molon wrote: In article 1122588119.285579@ftpsrv1, frederick says... The fact that the dust is visible, and that the image is not very sharp indicates to me that a very small aperture was used - as does the motion blur which tells me that a fast shutter speed was not used. Above about f11, sharpness will be lost on a dslr like the D70 At what aperture is the diffraction limit for a camera like the D70 ? Take a look. http://www.geocities.com/angels2000photos/diffract.jpg I think that you can see slight loss of acutance even at f11 - but not enough that you would even notice on a print - even a large one. By f16 it's pretty visible, by f22 it's very significant. Those are 1:1 crops, but I think loss of sharpness is going to be noticeable on anything but a very small print by the time you get to f16 of greater. http://www.geocities.com/angels2000photos/diffract.jpg Frederick Thanks for that info - I'm a pretty much a noob at this lark Do you have any links for further reading easily to hand http://www.cambridgeincolour.com/tutorials.htm http://www.cambridgeincolour.com/tut...otography.htm# I think that is a good source of information - and particularly in explaining the effects of sensor format, aperture, focal length on DOF, taking into account diffraction, and most importantly the different parameters that apply for assessing sharpness on final prints - such as size of print and viewing distance. It also explains why trade-off between loss of acutance or resolution from diffraction may be acceptable when extra depth of field is desired. Thanks for the reply Frederick I'll have a read later Best regards Tim -- http://www.timdenning.myby.co.uk/ |
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