Monday 27 September 2010

Sharpness-How sharp is sharp

When it comes to the sharpness of an image it seems that everybody has their own standards of what is sharp and what isn't, When you are doing photography as a business Sharpness is everything, Show a client or agency a set of soft images and that will be the last call you get from them, I see lots and lots of images on Photographic forums that are not just unsharp but very soft or out of focus, Sometimes the persons opening line is 'i know its soft but' well to me there are no buts unless its a yeti running through a dark forest, These days even kit lenses are sharp and base cameras give excellent results so it must be down to user error, Once again excessive cropping crops up, The thought that a high megapixel camera is great because you crop the image in half to make the subject bigger is fine if the subject is sharp, If it isn't any cropping will make it look a lot worse and highlight any camera shake or subject movement, Technique is everything, The most common cause of an unsharp image is using too low a shutter speed, long lens technique or back or front focusing, The first is easily cured by using a higher ISO-Better a grainy sharp image that a grain free soft image-Long lens technique i covered here a long time ago but the use of a good quality tripod and head is a start, Keeping the tripod height to a minimum helps and a bean bag is even better, If you are constantly getting part of the image sharp but not where the focus point is then your camera is either front or back focusing, If you have a newish camera you could have a go at setting the focus yourself but i would advise sending it back and getting your camera calibrated to your lenses by the camera manufacturer, Now how sharp is sharp, That's a difficult one as you can have acceptably sharp and critically sharp, If the image prints to a certain size and looks good that could be classed as acceptably sharp but an image needs to be critically sharp to be printed huge-one mans critically sharp is another mans acceptably sharp and we all have our own standards, All i can say is that there are a lot of people using very expensive equipment and not getting critically or even acceptably sharp images on the forums but with a little thought and practice its not that difficult to get on a consistent basis
Here is an image i took last week in my home studio

Now heres a huge crop of her eye

Now thats critically sharp
The above was taken with the D3s and a 24-70 lens handheld but the shutter speed was 1/125 so it should be sharp but flash always helps to make an image sharp whether you are indoors or outside

This image was taken with a D300 and 600mm lens so in essence 850mm focal length, The shutter speed was 1/250 which is on the low side but a solid tripod and head and good long lens technique has given a very sharp image that can easily be printed beyond A3+ and look great

And a crop of the eye


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