Originally Posted by edfrometown
Originally Posted by neuroanatomist
Very well said
Originally Posted by edfrometown
Originally Posted by neuroanatomist
Very well said
Originally Posted by neuroanatomist
A simple solution to the deeper depth of field is to take several shots (focus on foreground, midground, background) and stack them into Photoshop, run a script, blend the layers, and voila, you have a deep depth of field. This technique works best for mostly static environments, but can be used effectively with slight movement of the subject matter. Then, one can use an f/# below the DLA of the particular camera, without compromising the sharpness of the image.
Well worth the cost of the program, considering how much we spend on our equipment.
My 2 cents....
Originally Posted by pin008
Well, it is the size of the airy disc for a given wavelength lambda, given that you have a circular unobstructed aperture. It is not necessarily impossible to resolve details beyond this limit, so what your textbook says is only approximately true (though all textbooks seem to say the same thing []) For example, it is possible to resolve double stars whose angular separation is less than 1.22λ/D. Maybe you'll see two discs not completely separated, but you can tell there are two stars. Also, telescopes with large central obstructions tend to spread light away from the center of the airy disc (ie, they have a low strehl ratio). This is considered bad, but such telescopes can sometimes resolve double stars that are closer than unobstructed scopes with the same clear aperture.
Originally Posted by pin008
You yourself showed (with your example involving the 7D) that it does not. Your example showed that an 18mp sensor will show more detail than a 10mp sensor, even if the image is blurred enough that the blur is detectable with the 10mp sensor. Of course, if the 10mp image is very blurry, the advantage in going to 18mp will be very small, but if the 10mp image is right at the DLA, I think there will be noticeable improvement in moving to 18mp.
Furthermore, if you have a super high resolution sensor, diffraction can be deconvolved effectively using maximum entropy or other algorithms. A 4" telescope can, in theory, produce images which show details much smaller than an arcsecond- far beyond the Rayleigh criterion.
There is nothing magic about DLA. It is not a point beyond which no information is gained. It is simply the aperture which gives an airy disc about the size of a pixel.
Seems to have stopped the string!